The span iterator travels over the indexes of the interval_tree, not the nodes, and classifies spans of indexes as either 'used' or 'hole'.

'used' spans are fully covered by nodes in the tree and 'hole' spans have no node intersecting the span.

This is done greedily such that spans are maximally sized and every iteration step switches between used/hole.

As an example a trivial allocator can be written as:

for (interval_tree_span_iter_first(&span, itree, 0, ULONG_MAX); !interval_tree_span_iter_done(&span); interval_tree_span_iter_next(&span)) if (span.is_hole && span.last_hole - span.start_hole >= allocation_size - 1) return span.start_hole;

With all the tricky boundary conditions handled by the library code.

The following iommufd patches have several algorithms for its overlapping node interval trees that are significantly simplified with this kind of iteration primitive. As it seems generally useful, put it into lib/.

Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- .clang-format | 1 + include/linux/interval_tree.h | 50 +++++++++++++ lib/Kconfig | 4 ++ lib/interval_tree.c | 132 ++++++++++++++++++++++++++++++++++ 4 files changed, 187 insertions(+)

diff --git a/.clang-format b/.clang-format index 1247d54f9e49fa..96d07786dcfb46 100644 --- a/.clang-format +++ b/.clang-format @@ -440,6 +440,7 @@ ForEachMacros: - 'inet_lhash2_for_each_icsk' - 'inet_lhash2_for_each_icsk_continue' - 'inet_lhash2_for_each_icsk_rcu' + - 'interval_tree_for_each_span' - 'intlist__for_each_entry' - 'intlist__for_each_entry_safe' - 'kcore_copy__for_each_phdr' diff --git a/include/linux/interval_tree.h b/include/linux/interval_tree.h index 288c26f50732d7..3c803379b83cd8 100644 --- a/include/linux/interval_tree.h +++ b/include/linux/interval_tree.h @@ -27,4 +27,54 @@ extern struct interval_tree_node * interval_tree_iter_next(struct interval_tree_node *node, unsigned long start, unsigned long last);

+/* + * This iterator travels over spans in an interval tree. It does not return + * nodes but classifies each span as either a hole, where no nodes intersect, or + * a used, which is fully covered by nodes. Each iteration step toggles between + * hole and used until the entire range is covered. The returned spans always + * fully cover the requested range. + * + * The iterator is greedy, it always returns the largest hole or used possible, + * consolidating all consecutive nodes. + * + * Only is_hole, start_hole/used and last_hole/used are part of the external + * interface. + */ +struct interval_tree_span_iter { + struct interval_tree_node *nodes[2]; + unsigned long first_index; + unsigned long last_index; + union { + unsigned long start_hole; + unsigned long start_used; + }; + union { + unsigned long last_hole; + unsigned long last_used; + }; + /* 0 == used, 1 == is_hole, -1 == done iteration */ + int is_hole; +}; + +void interval_tree_span_iter_first(struct interval_tree_span_iter *state, + struct rb_root_cached *itree, + unsigned long first_index, + unsigned long last_index); +void interval_tree_span_iter_advance(struct interval_tree_span_iter *iter, + struct rb_root_cached *itree, + unsigned long new_index); +void interval_tree_span_iter_next(struct interval_tree_span_iter *state); + +static inline bool +interval_tree_span_iter_done(struct interval_tree_span_iter *state) +{ + return state->is_hole == -1; +} + +#define interval_tree_for_each_span(span, itree, first_index, last_index) \ + for (interval_tree_span_iter_first(span, itree, \ + first_index, last_index); \ + !interval_tree_span_iter_done(span); \ + interval_tree_span_iter_next(span)) + #endif /* _LINUX_INTERVAL_TREE_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 9bbf8a4b2108e6..c6c323fd251721 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -479,6 +479,10 @@ config INTERVAL_TREE

for more information.

+config INTERVAL_TREE_SPAN_ITER + bool + depends on INTERVAL_TREE + config XARRAY_MULTI bool help diff --git a/lib/interval_tree.c b/lib/interval_tree.c index 593ce56ece5050..6edfb83894af8e 100644 --- a/lib/interval_tree.c +++ b/lib/interval_tree.c @@ -15,3 +15,135 @@ EXPORT_SYMBOL_GPL(interval_tree_insert); EXPORT_SYMBOL_GPL(interval_tree_remove); EXPORT_SYMBOL_GPL(interval_tree_iter_first); EXPORT_SYMBOL_GPL(interval_tree_iter_next); + +#ifdef CONFIG_INTERVAL_TREE_SPAN_ITER +static void +interval_tree_span_iter_next_gap(struct interval_tree_span_iter *state) +{ + struct interval_tree_node *cur = state->nodes[1]; + + /* + * Roll nodes[1] into nodes[0] by advancing nodes[1] to the end of a + * contiguous span of nodes. This makes nodes[0]->last the end of that + * contiguous span of valid indexes that started at the original + * nodes[1]->start. nodes[1] is now the next node and a hole is between + * nodes[0] and [1]. + */ + state->nodes[0] = cur; + do { + if (cur->last > state->nodes[0]->last) + state->nodes[0] = cur; + cur = interval_tree_iter_next(cur, state->first_index, + state->last_index); + } while (cur && (state->nodes[0]->last >= cur->start || + state->nodes[0]->last + 1 == cur->start)); + state->nodes[1] = cur; +} + +void interval_tree_span_iter_first(struct interval_tree_span_iter *iter, + struct rb_root_cached *itree, + unsigned long first_index, + unsigned long last_index) +{ + iter->first_index = first_index; + iter->last_index = last_index; + iter->nodes[0] = NULL; + iter->nodes[1] = + interval_tree_iter_first(itree, first_index, last_index); + if (!iter->nodes[1]) { + /* No nodes intersect the span, whole span is hole */ + iter->start_hole = first_index; + iter->last_hole = last_index; + iter->is_hole = 1; + return; + } + if (iter->nodes[1]->start > first_index) { + /* Leading hole on first iteration */ + iter->start_hole = first_index; + iter->last_hole = iter->nodes[1]->start - 1; + iter->is_hole = 1; + interval_tree_span_iter_next_gap(iter); + return; + } + + /* Starting inside a used */ + iter->start_used = first_index; + iter->is_hole = 0; + interval_tree_span_iter_next_gap(iter); + iter->last_used = iter->nodes[0]->last; + if (iter->last_used >= last_index) { + iter->last_used = last_index; + iter->nodes[0] = NULL; + iter->nodes[1] = NULL; + } +} +EXPORT_SYMBOL_GPL(interval_tree_span_iter_first); + +void interval_tree_span_iter_next(struct interval_tree_span_iter *iter) +{ + if (!iter->nodes[0] && !iter->nodes[1]) { + iter->is_hole = -1; + return; + } + + if (iter->is_hole) { + iter->start_used = iter->last_hole + 1; + iter->last_used = iter->nodes[0]->last; + if (iter->last_used >= iter->last_index) { + iter->last_used = iter->last_index; + iter->nodes[0] = NULL; + iter->nodes[1] = NULL; + } + iter->is_hole = 0; + return; + } + + if (!iter->nodes[1]) { + /* Trailing hole */ + iter->start_hole = iter->nodes[0]->last + 1; + iter->last_hole = iter->last_index; + iter->nodes[0] = NULL; + iter->is_hole = 1; + return; + } + + /* must have both nodes[0] and [1], interior hole */ + iter->start_hole = iter->nodes[0]->last + 1; + iter->last_hole = iter->nodes[1]->start - 1; + iter->is_hole = 1; + interval_tree_span_iter_next_gap(iter); +} +EXPORT_SYMBOL_GPL(interval_tree_span_iter_next); + +/* + * Advance the iterator index to a specific position. The returned used/hole is + * updated to start at new_index. This is faster than calling + * interval_tree_span_iter_first() as it can avoid full searches in several + * cases where the iterator is already set. + */ +void interval_tree_span_iter_advance(struct interval_tree_span_iter *iter, + struct rb_root_cached *itree, + unsigned long new_index) +{ + if (iter->is_hole == -1) + return; + + iter->first_index = new_index; + if (new_index == iter->last_index) { + iter->is_hole = -1; + return; + } + + /* Rely on the union aliasing hole/used */ + if (iter->start_hole <= new_index && new_index <= iter->last_hole) { + iter->start_hole = new_index; + return; + } + if (new_index == iter->last_hole + 1) + interval_tree_span_iter_next(iter); + else + interval_tree_span_iter_first(iter, itree, new_index, + iter->last_index); +} +EXPORT_SYMBOL_GPL(interval_tree_span_iter_advance); +#endif

From: Kevin Tian kevin.tian@intel.com

Add iommufd to the documentation tree.

Signed-off-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/iommufd.rst | 222 ++++++++++++++++++++++++ 2 files changed, 223 insertions(+) create mode 100644 Documentation/userspace-api/iommufd.rst

diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index c78da9ce0ec44e..f16337bdb8520f 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -25,6 +25,7 @@ place where this information is gathered. ebpf/index ioctl/index iommu + iommufd media/index netlink/index sysfs-platform_profile diff --git a/Documentation/userspace-api/iommufd.rst b/Documentation/userspace-api/iommufd.rst new file mode 100644 index 00000000000000..3e1856469d96dd --- /dev/null +++ b/Documentation/userspace-api/iommufd.rst @@ -0,0 +1,222 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +======= +IOMMUFD +======= + +:Author: Jason Gunthorpe +:Author: Kevin Tian + +Overview +======== + +IOMMUFD is the user API to control the IOMMU subsystem as it relates to managing +IO page tables that point at user space memory. It intends to be general and +consumable by any driver that wants to DMA to userspace. These drivers are +eventually expected to deprecate any internal IOMMU logic, if existing (e.g. +vfio_iommu_type1.c). + +At minimum iommufd provides a universal support of managing I/O address spaces +and I/O page tables for all IOMMUs, with room in the design to add non-generic +features to cater to specific hardware functionality. + +In this context the capital letter (IOMMUFD) refers to the subsystem while the +small letter (iommufd) refers to the file descriptors created via /dev/iommu to +run the user API over. + +Key Concepts +============ + +User Visible Objects +-------------------- + +Following IOMMUFD objects are exposed to userspace: + +- IOMMUFD_OBJ_IOAS, representing an I/O address space (IOAS) allowing map/unmap + of user space memory into ranges of I/O Virtual Address (IOVA). + + The IOAS is a functional replacement for the VFIO container, and like the VFIO + container copies its IOVA map to a list of iommu_domains held within it. + +- IOMMUFD_OBJ_DEVICE, representing a device that is bound to iommufd by an + external driver. + +- IOMMUFD_OBJ_HW_PAGETABLE, representing an actual hardware I/O page table (i.e. + a single struct iommu_domain) managed by the iommu driver. + + The IOAS has a list of HW_PAGETABLES that share the same IOVA mapping and the + IOAS will synchronize its mapping with each member HW_PAGETABLE. + +All user-visible objects are destroyed via the IOMMU_DESTROY uAPI. + +Linkage between user-visible objects and external kernel datastructures are +reflected by the arrows, with numbers referring to certain +operations creating the objects and links:: + + _________________________________________________________ + | iommufd | + | [1] | + | _________________ | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | [3] [2] | + | | | ____________ __________ | + | | IOAS |<--| |<------| | | + | | | |HW_PAGETABLE| | DEVICE | | + | | | |____________| |__________| | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | |_________________| | | | + | | | | | + |_________|___________________|___________________|_______| + | | | + | _____v______ _______v_____ + | PFN storage | | | | + |------------>|iommu_domain| |struct device| + |____________| |_____________| + +1. IOMMUFD_OBJ_IOAS is created via the IOMMU_IOAS_ALLOC uAPI. One iommufd can + hold multiple IOAS objects. IOAS is the most generic object and does not + expose interfaces that are specific to single IOMMU drivers. All operations + on the IOAS must operate equally on each of the iommu_domains that are inside + it. + +2. IOMMUFD_OBJ_DEVICE is created when an external driver calls the IOMMUFD kAPI + to bind a device to an iommufd. The external driver is expected to implement + proper uAPI for userspace to initiate the binding operation. Successful + completion of this operation establishes the desired DMA ownership over the + device. The external driver must set driver_managed_dma flag and must not + touch the device until this operation succeeds. + +3. IOMMUFD_OBJ_HW_PAGETABLE is created when an external driver calls the IOMMUFD + kAPI to attach a bound device to an IOAS. Similarly the external driver uAPI + allows userspace to initiate the attaching operation. If a compatible + pagetable already exists then it is reused for the attachment. Otherwise a + new pagetable object (and a new iommu_domain) is created. Successful + completion of this operation sets up the linkages among an IOAS, a device and + an iommu_domain. Once this completes the device could do DMA. + + Every iommu_domain inside the IOAS is also represented to userspace as a + HW_PAGETABLE object. + + NOTE: Future additions to IOMMUFD will provide an API to create and + manipulate the HW_PAGETABLE directly. + +One device can only bind to one iommufd (due to DMA ownership claim) and attach +to at most one IOAS object (no support of PASID yet). + +Currently only PCI device is allowed. + +Kernel Datastructure +-------------------- + +User visible objects are backed by following datastructures: + +- iommufd_ioas for IOMMUFD_OBJ_IOAS. +- iommufd_device for IOMMUFD_OBJ_DEVICE. +- iommufd_hw_pagetable for IOMMUFD_OBJ_HW_PAGETABLE. + +Several terminologies when looking at these datastructures: + +- Automatic domain, referring to an iommu domain created automatically when + attaching a device to an IOAS object. This is compatible to the semantics of + VFIO type1. + +- Manual domain, referring to an iommu domain designated by the user as the + target pagetable to be attached to by a device. Though currently no user API + for userspace to directly create such domain, the datastructure and algorithms + are ready for that usage. + +- In-kernel user, referring to something like a VFIO mdev that is accessing the + IOAS and using a 'struct page *' for CPU based access. Such users require an + isolation granularity smaller than what an iommu domain can afford. They must + manually enforce the IOAS constraints on DMA buffers before those buffers can + be accessed by mdev. Though no kernel API for an external driver to bind a + mdev, the datastructure and algorithms are ready for such usage. + +iommufd_ioas serves as the metadata datastructure to manage how IOVA ranges are +mapped to memory pages, composed of: + +- struct io_pagetable holding the IOVA map +- struct iopt_areas representing populated portions of IOVA +- struct iopt_pages representing the storage of PFNs +- struct iommu_domain representing the IO page table in the IOMMU +- struct iopt_pages_access representing in-kernel users of PFNs +- struct xarray pinned_pfns holding a list of pages pinned by + in-kernel Users + +Each iopt_pages represents a logical linear array of full PFNs. The PFNs are +ultimately derived from userspave VAs via an mm_struct. Once they have been +pinned the PFN is stored in an iommu_domain's IOPTEs or inside the pinned_pages +xarray if they are being "software accessed". + +PFN have to be copied between all combinations of storage locations, depending +on what domains are present and what kinds of in-kernel "software access" users +exists. The mechanism ensures that a page is pinned only once. + +An io_pagetable is composed of iopt_areas pointing at iopt_pages, along with a +list of iommu_domains that mirror the IOVA to PFN map. + +Multiple io_pagetable's, through their iopt_area's, can share a single +iopt_pages which avoids multi-pinning and double accounting of page consumption. + +iommufd_ioas is sharable between subsystems, e.g. VFIO and VDPA, as long as +devices managed by different subsystems are bound to a same iommufd. + +IOMMUFD User API +================ + +.. kernel-doc:: include/uapi/linux/iommufd.h + +IOMMUFD Kernel API +================== + +The IOMMUFD kAPI is device-centric with group-related tricks managed behind the +scene. This allows the external driver calling such kAPI to implement a simple +device-centric uAPI for connecting its device to an iommufd, instead of +explicitly imposing the group semantics in its uAPI (as VFIO does). + +.. kernel-doc:: drivers/iommu/iommufd/device.c + :export: + +VFIO and IOMMUFD +---------------- + +Connecting a VFIO device to iommufd can be done in two approaches. + +First is a VFIO compatible way by directly implementing the /dev/vfio/vfio +container IOCTLs by mapping them into io_pagetable operations. Doing so allows +the use of iommufd in legacy VFIO applications by symlinking /dev/vfio/vfio to +/dev/iommufd or extending VFIO to SET_CONTAINER using an iommufd instead of a +container fd. + +The second approach directly extends VFIO to support a new set of device-centric +user API based on aforementioned IOMMUFD kernel API. It requires userspace +change but better matches the IOMMUFD API semantics and easier to support new +iommufd features when comparing it to the first approach. + +Currently both approaches are still work-in-progress. + +There are still a few gaps to be resolved to catch up with VFIO type1, as +documented in iommufd_vfio_check_extension(). + +Future TODOs +============ + +Currently IOMMUFD supports only kernel-managed I/O page table, similar to VFIO +type1. New features on the radar include: + + - Binding iommu_domain's to PASID/SSID + - Userspace page tables, for ARM, x86 and S390 + - Kernel bypass'd invalidation of user page tables + - Re-use of the KVM page table in the IOMMU + - Dirty page tracking in the IOMMU + - Runtime Increase/Decrease of IOPTE size + - PRI support with faults resolved in userspace

The iopt_pages which represents a logical linear list of full PFNs held in different storage tiers. Each area points to a slice of exactly one iopt_pages, and each iopt_pages can have multiple areas and accesses.

The three storage tiers are managed to meet these objectives:

- If no iommu_domain or in-kerenel access exists then minimal memory should be consumed by iomufd - If a page has been pinned then an iopt_pages will not pin it again - If an in-kernel access exists then the xarray must provide the backing storage to avoid allocations on domain removals - Otherwise any iommu_domain will be used for storage

In a common configuration with only an iommu_domain the iopt_pages does not allocate significant memory itself.

The external interface for pages has several logical operations:

iopt_area_fill_domain() will load the PFNs from storage into a single domain. This is used when attaching a new domain to an existing IOAS.

iopt_area_fill_domains() will load the PFNs from storage into multiple domains. This is used when creating a new IOVA map in an existing IOAS

iopt_pages_add_access() creates an iopt_pages_access that tracks an in-kernel access of PFNs. This is some external driver that might be accessing the IOVA using the CPU, or programming PFNs with the DMA API. ie a VFIO mdev.

iopt_pages_rw_access() directly perform a memcpy on the PFNs, without the overhead of iopt_pages_add_access()

iopt_pages_fill_xarray() will load PFNs into the xarray and return a 'struct page *' array. It is used by iopt_pages_access's to extract PFNs for in-kernel use. iopt_pages_fill_from_xarray() is a fast path when it is known the xarray is already filled.

As an iopt_pages can be referred to in slices by many areas and accesses it uses interval trees to keep track of which storage tiers currently hold the PFNs. On a page-by-page basis any request for a PFN will be satisfied from one of the storage tiers and the PFN copied to target domain/array.

Unfill actions are similar, on a page by page basis domains are unmapped, xarray entries freed or struct pages fully put back.

Significant complexity is required to fully optimize all of these data motions. The implementation calculates the largest consecutive range of same-storage indexes and operates in blocks. The accumulation of PFNs always generates the largest contiguous PFN range possible to optimize and this gathering can cross storage tier boundaries. For cases like 'fill domains' care is taken to avoid duplicated work and PFNs are read once and pushed into all domains.

The map/unmap interaction with the iommu_domain always works in contiguous PFN blocks. The implementation does not require or benefit from any split/merge optimization in the iommu_domain driver.

This design suggests several possible improvements in the IOMMU API that would greatly help performance, particularly a way for the driver to map and read the pfns lists instead of working with one driver call per page to read, and one driver call per contiguous range to store.

Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/io_pagetable.h | 73 +++ drivers/iommu/iommufd/pages.c | 803 ++++++++++++++++++++++++++- 2 files changed, 872 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index b74bf01ffc52c2..083451afcdcf46 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -49,6 +49,14 @@ struct iopt_area { unsigned int num_accesses; };

+int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages); +void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages); + +int iopt_area_fill_domain(struct iopt_area *area, struct iommu_domain *domain); +void iopt_area_unfill_domain(struct iopt_area *area, struct iopt_pages *pages, + struct iommu_domain *domain); +void iopt_unmap_domain(struct io_pagetable *iopt, struct iommu_domain *domain); + static inline unsigned long iopt_area_index(struct iopt_area *area) { return area->pages_node.start; @@ -69,6 +77,39 @@ static inline unsigned long iopt_area_last_iova(struct iopt_area *area) return area->node.last; }

+static inline size_t iopt_area_length(struct iopt_area *area) +{ + return (area->node.last - area->node.start) + 1; +} + +#define __make_iopt_iter(name) \ + static inline struct iopt_##name *iopt_##name##_iter_first( \ + struct io_pagetable *iopt, unsigned long start, \ + unsigned long last) \ + { \ + struct interval_tree_node *node; \ + \ + lockdep_assert_held(&iopt->iova_rwsem); \ + node = interval_tree_iter_first(&iopt->name##_itree, start, \ + last); \ + if (!node) \ + return NULL; \ + return container_of(node, struct iopt_##name, node); \ + } \ + static inline struct iopt_##name *iopt_##name##_iter_next( \ + struct iopt_##name *last_node, unsigned long start, \ + unsigned long last) \ + { \ + struct interval_tree_node *node; \ + \ + node = interval_tree_iter_next(&last_node->node, start, last); \ + if (!node) \ + return NULL; \ + return container_of(node, struct iopt_##name, node); \ + } + +__make_iopt_iter(area) + enum { IOPT_PAGES_ACCOUNT_NONE = 0, IOPT_PAGES_ACCOUNT_USER = 1, @@ -106,4 +147,36 @@ struct iopt_pages { struct rb_root_cached domains_itree; };

+struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length, + bool writable); +void iopt_release_pages(struct kref *kref); +static inline void iopt_put_pages(struct iopt_pages *pages) +{ + kref_put(&pages->kref, iopt_release_pages); +} + +void iopt_pages_fill_from_xarray(struct iopt_pages *pages, unsigned long start, + unsigned long last, struct page **out_pages); +int iopt_pages_fill_xarray(struct iopt_pages *pages, unsigned long start, + unsigned long last, struct page **out_pages); +void iopt_pages_unfill_xarray(struct iopt_pages *pages, unsigned long start, + unsigned long last); + +int iopt_pages_add_access(struct iopt_pages *pages, unsigned long start, + unsigned long last, struct page **out_pages, + unsigned int flags); +void iopt_pages_remove_access(struct iopt_area *area, unsigned long start, + unsigned long last); +int iopt_pages_rw_access(struct iopt_pages *pages, unsigned long start_byte, + void *data, unsigned long length, unsigned int flags); + +/* + * Each interval represents an active iopt_access_pages(), it acts as an + * interval lock that keeps the PFNs pinned and stored in the xarray. + */ +struct iopt_pages_access { + struct interval_tree_node node; + refcount_t refcount; +}; + #endif diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index dd74aea60d2cc3..a09e197524be3b 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -162,6 +162,18 @@ static void iommu_unmap_nofail(struct iommu_domain *domain, unsigned long iova, WARN_ON(ret != size); }

+static void iopt_area_unmap_domain_range(struct iopt_area *area, + struct iommu_domain *domain, + unsigned long start_index, + unsigned long last_index) +{ + unsigned long start_iova = iopt_area_index_to_iova(area, start_index); + + iommu_unmap_nofail(domain, start_iova, + iopt_area_index_to_iova_last(area, last_index) - + start_iova + 1); +} + static struct iopt_area *iopt_pages_find_domain_area(struct iopt_pages *pages, unsigned long index) { @@ -182,7 +194,7 @@ static struct iopt_area *iopt_pages_find_domain_area(struct iopt_pages *pages, */ struct pfn_batch { unsigned long *pfns; - u16 *npfns; + u32 *npfns; unsigned int array_size; unsigned int end; unsigned int total_pfns; @@ -232,7 +244,7 @@ static int __batch_init(struct pfn_batch *batch, size_t max_pages, void *backup, if (!batch->pfns) return -ENOMEM; batch->array_size = size / elmsz; - batch->npfns = (u16 *)(batch->pfns + batch->array_size); + batch->npfns = (u32 *)(batch->pfns + batch->array_size); batch_clear(batch); return 0; } @@ -257,10 +269,11 @@ static void batch_destroy(struct pfn_batch *batch, void *backup) /* true if the pfn could be added, false otherwise */ static bool batch_add_pfn(struct pfn_batch *batch, unsigned long pfn) { - /* FIXME: U16 is too small */ + const unsigned int MAX_NPFNS = type_max(typeof(*batch->npfns)); + if (batch->end && pfn == batch->pfns[batch->end - 1] + batch->npfns[batch->end - 1] && - batch->npfns[batch->end - 1] != U16_MAX) { + batch->npfns[batch->end - 1] != MAX_NPFNS) { batch->npfns[batch->end - 1]++; batch->total_pfns++; return true; @@ -994,3 +1007,785 @@ static int pfn_reader_first(struct pfn_reader *pfns, struct iopt_pages *pages, } return 0; } + +struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length, + bool writable) +{ + struct iopt_pages *pages; + + /* + * The iommu API uses size_t as the length, and protect the DIV_ROUND_UP + * below from overflow + */ + if (length > SIZE_MAX - PAGE_SIZE || length == 0) + return ERR_PTR(-EINVAL); + + pages = kzalloc(sizeof(*pages), GFP_KERNEL_ACCOUNT); + if (!pages) + return ERR_PTR(-ENOMEM); + + kref_init(&pages->kref); + xa_init_flags(&pages->pinned_pfns, XA_FLAGS_ACCOUNT); + mutex_init(&pages->mutex); + pages->source_mm = current->mm; + mmgrab(pages->source_mm); + pages->uptr = (void __user *)ALIGN_DOWN((uintptr_t)uptr, PAGE_SIZE); + pages->npages = DIV_ROUND_UP(length + (uptr - pages->uptr), PAGE_SIZE); + pages->access_itree = RB_ROOT_CACHED; + pages->domains_itree = RB_ROOT_CACHED; + pages->writable = writable; + if (capable(CAP_IPC_LOCK)) + pages->account_mode = IOPT_PAGES_ACCOUNT_NONE; + else + pages->account_mode = IOPT_PAGES_ACCOUNT_USER; + pages->source_task = current->group_leader; + get_task_struct(current->group_leader); + pages->source_user = get_uid(current_user()); + return pages; +} + +void iopt_release_pages(struct kref *kref) +{ + struct iopt_pages *pages = container_of(kref, struct iopt_pages, kref); + + WARN_ON(!RB_EMPTY_ROOT(&pages->access_itree.rb_root)); + WARN_ON(!RB_EMPTY_ROOT(&pages->domains_itree.rb_root)); + WARN_ON(pages->npinned); + WARN_ON(!xa_empty(&pages->pinned_pfns)); + mmdrop(pages->source_mm); + mutex_destroy(&pages->mutex); + put_task_struct(pages->source_task); + free_uid(pages->source_user); + kfree(pages); +} + +static void +iopt_area_unpin_domain(struct pfn_batch *batch, struct iopt_area *area, + struct iopt_pages *pages, struct iommu_domain *domain, + unsigned long start_index, unsigned long last_index, + unsigned long *unmapped_end_index, + unsigned long real_last_index) +{ + while (start_index <= last_index) { + unsigned long batch_last_index; + + if (*unmapped_end_index <= last_index) { + unsigned long start = + max(start_index, *unmapped_end_index); + + batch_from_domain(batch, domain, area, start, + last_index); + batch_last_index = start + batch->total_pfns - 1; + } else { + batch_last_index = last_index; + } + + /* + * unmaps must always 'cut' at a place where the pfns are not + * contiguous to pair with the maps that always install + * contiguous pages. Thus, if we have to stop unpinning in the + * middle of the domains we need to keep reading pfns until we + * find a cut point to do the unmap. The pfns we read are + * carried over and either skipped or integrated into the next + * batch. + */ + if (batch_last_index == last_index && + last_index != real_last_index) + batch_from_domain_continue(batch, domain, area, + last_index + 1, + real_last_index); + + if (*unmapped_end_index <= batch_last_index) { + iopt_area_unmap_domain_range( + area, domain, *unmapped_end_index, + start_index + batch->total_pfns - 1); + *unmapped_end_index = start_index + batch->total_pfns; + } + + /* unpin must follow unmap */ + batch_unpin(batch, pages, 0, + batch_last_index - start_index + 1); + start_index = batch_last_index + 1; + + batch_clear_carry(batch, + *unmapped_end_index - batch_last_index - 1); + } +} + +static void __iopt_area_unfill_domain(struct iopt_area *area, + struct iopt_pages *pages, + struct iommu_domain *domain, + unsigned long last_index) +{ + struct interval_tree_double_span_iter span; + unsigned long start_index = iopt_area_index(area); + unsigned long unmapped_end_index = start_index; + u64 backup[BATCH_BACKUP_SIZE]; + struct pfn_batch batch; + + lockdep_assert_held(&pages->mutex); + + batch_init_backup(&batch, last_index + 1, backup, sizeof(backup)); + interval_tree_for_each_double_span(&span, &pages->domains_itree, + &pages->access_itree, start_index, + last_index) { + if (span.is_used) { + batch_skip_carry(&batch, + span.last_used - span.start_used + 1); + continue; + } + iopt_area_unpin_domain(&batch, area, pages, domain, + span.start_hole, span.last_hole, + &unmapped_end_index, last_index); + } + if (unmapped_end_index != last_index + 1) + iopt_area_unmap_domain_range(area, domain, unmapped_end_index, + last_index); + WARN_ON(batch.total_pfns); + batch_destroy(&batch, backup); + update_unpinned(pages); +} + +static void iopt_area_unfill_partial_domain(struct iopt_area *area, + struct iopt_pages *pages, + struct iommu_domain *domain, + unsigned long end_index) +{ + if (end_index != iopt_area_index(area)) + __iopt_area_unfill_domain(area, pages, domain, end_index - 1); +} + +/** + * iopt_unmap_domain() - Unmap without unpinning PFNs in a domain + * @iopt: The iopt the domain is part of + * @domain: The domain to unmap + * + * The caller must know that unpinning is not required, usually because there + * are other domains in the iopt. + */ +void iopt_unmap_domain(struct io_pagetable *iopt, struct iommu_domain *domain) +{ + struct interval_tree_span_iter span; + + interval_tree_for_each_span(&span, &iopt->area_itree, 0, ULONG_MAX) + if (!span.is_hole) + iommu_unmap_nofail(domain, span.start_used, + span.last_used - span.start_used + + 1); +} + +/** + * iopt_area_unfill_domain() - Unmap and unpin PFNs in a domain + * @area: IOVA area to use + * @pages: page supplier for the area (area->pages is NULL) + * @domain: Domain to unmap from + * + * The domain should be removed from the domains_itree before calling. The + * domain will always be unmapped, but the PFNs may not be unpinned if there are + * still accesses. + */ +void iopt_area_unfill_domain(struct iopt_area *area, struct iopt_pages *pages, + struct iommu_domain *domain) +{ + __iopt_area_unfill_domain(area, pages, domain, + iopt_area_last_index(area)); +} + +/** + * iopt_area_fill_domain() - Map PFNs from the area into a domain + * @area: IOVA area to use + * @domain: Domain to load PFNs into + * + * Read the pfns from the area's underlying iopt_pages and map them into the + * given domain. Called when attaching a new domain to an io_pagetable. + */ +int iopt_area_fill_domain(struct iopt_area *area, struct iommu_domain *domain) +{ + struct pfn_reader pfns; + int rc; + + lockdep_assert_held(&area->pages->mutex); + + rc = pfn_reader_first(&pfns, area->pages, iopt_area_index(area), + iopt_area_last_index(area)); + if (rc) + return rc; + + while (!pfn_reader_done(&pfns)) { + rc = batch_to_domain(&pfns.batch, domain, area, + pfns.batch_start_index); + if (rc) + goto out_unmap; + + rc = pfn_reader_next(&pfns); + if (rc) + goto out_unmap; + } + + rc = pfn_reader_update_pinned(&pfns); + if (rc) + goto out_unmap; + goto out_destroy; + +out_unmap: + iopt_area_unfill_partial_domain(area, area->pages, domain, + pfns.batch_start_index); +out_destroy: + pfn_reader_destroy(&pfns); + return rc; +} + +/** + * iopt_area_fill_domains() - Install PFNs into the area's domains + * @area: The area to act on + * @pages: The pages associated with the area (area->pages is NULL) + * + * Called during area creation. The area is freshly created and not inserted in + * the domains_itree yet. PFNs are read and loaded into every domain held in the + * area's io_pagetable and the area is installed in the domains_itree. + * + * On failure all domains are left unchanged. + */ +int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages) +{ + struct pfn_reader pfns; + struct iommu_domain *domain; + unsigned long unmap_index; + unsigned long index; + int rc; + + lockdep_assert_held(&area->iopt->domains_rwsem); + + if (xa_empty(&area->iopt->domains)) + return 0; + + mutex_lock(&pages->mutex); + rc = pfn_reader_first(&pfns, pages, iopt_area_index(area), + iopt_area_last_index(area)); + if (rc) + goto out_unlock; + + while (!pfn_reader_done(&pfns)) { + xa_for_each(&area->iopt->domains, index, domain) { + rc = batch_to_domain(&pfns.batch, domain, area, + pfns.batch_start_index); + if (rc) + goto out_unmap; + } + + rc = pfn_reader_next(&pfns); + if (rc) + goto out_unmap; + } + rc = pfn_reader_update_pinned(&pfns); + if (rc) + goto out_unmap; + + area->storage_domain = xa_load(&area->iopt->domains, 0); + interval_tree_insert(&area->pages_node, &pages->domains_itree); + goto out_destroy; + +out_unmap: + xa_for_each(&area->iopt->domains, unmap_index, domain) { + unsigned long end_index = pfns.batch_start_index; + + if (unmap_index <= index) + end_index = pfns.batch_end_index; + + /* + * The area is not yet part of the domains_itree so we have to + * manage the unpinning specially. The last domain does the + * unpin, every other domain is just unmapped. + */ + if (unmap_index != area->iopt->next_domain_id - 1) { + if (end_index != iopt_area_index(area)) + iopt_area_unmap_domain_range( + area, domain, iopt_area_index(area), + end_index - 1); + } else { + iopt_area_unfill_partial_domain(area, pages, domain, + end_index); + } + } +out_destroy: + pfn_reader_destroy(&pfns); +out_unlock: + mutex_unlock(&pages->mutex); + return rc; +} + +/** + * iopt_area_unfill_domains() - unmap PFNs from the area's domains + * @area: The area to act on + * @pages: The pages associated with the area (area->pages is NULL) + * + * Called during area destruction. This unmaps the iova's covered by all the + * area's domains and releases the PFNs. + */ +void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages) +{ + struct io_pagetable *iopt = area->iopt; + struct iommu_domain *domain; + unsigned long index; + + lockdep_assert_held(&iopt->domains_rwsem); + + mutex_lock(&pages->mutex); + if (!area->storage_domain) + goto out_unlock; + + xa_for_each(&iopt->domains, index, domain) + if (domain != area->storage_domain) + iopt_area_unmap_domain_range( + area, domain, iopt_area_index(area), + iopt_area_last_index(area)); + + interval_tree_remove(&area->pages_node, &pages->domains_itree); + iopt_area_unfill_domain(area, pages, area->storage_domain); + area->storage_domain = NULL; +out_unlock: + mutex_unlock(&pages->mutex); +} + +/** + * iopt_pages_unfill_xarray() - Update the xarry after removing an access + * @pages: The pages to act on + * @start_index: Starting PFN index + * @last_index: Last PFN index + * + * Called when an iopt_pages_access is removed, removes pages from the itree. + * The access should already be removed from the access_itree. + */ +void iopt_pages_unfill_xarray(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index) +{ + struct interval_tree_double_span_iter span; + u64 backup[BATCH_BACKUP_SIZE]; + struct pfn_batch batch; + bool batch_inited = false; + + lockdep_assert_held(&pages->mutex); + + interval_tree_for_each_double_span(&span, &pages->access_itree, + &pages->domains_itree, start_index, + last_index) { + if (!span.is_used) { + if (!batch_inited) { + batch_init_backup(&batch, + last_index - start_index + 1, + backup, sizeof(backup)); + batch_inited = true; + } + batch_from_xarray_clear(&batch, &pages->pinned_pfns, + span.start_hole, + span.last_hole); + batch_unpin(&batch, pages, 0, batch.total_pfns); + batch_clear(&batch); + } else if (span.is_used == 2) { + /* Covered by a domain */ + clear_xarray(&pages->pinned_pfns, span.start_used, + span.last_used); + } + /* Otherwise covered by an existing access */ + } + if (batch_inited) + batch_destroy(&batch, backup); + update_unpinned(pages); +} + +/** + * iopt_pages_fill_from_xarray() - Fast path for reading PFNs + * @pages: The pages to act on + * @start_index: The first page index in the range + * @last_index: The last page index in the range + * @out_pages: The output array to return the pages + * + * This can be called if the caller is holding a refcount on an + * iopt_pages_access that is known to have already been filled. It quickly reads + * the pages directly from the xarray. + * + * This is part of the SW iommu interface to read pages for in-kernel use. + */ +void iopt_pages_fill_from_xarray(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + XA_STATE(xas, &pages->pinned_pfns, start_index); + void *entry; + + rcu_read_lock(); + while (start_index <= last_index) { + entry = xas_next(&xas); + if (xas_retry(&xas, entry)) + continue; + WARN_ON(!xa_is_value(entry)); + *(out_pages++) = pfn_to_page(xa_to_value(entry)); + start_index++; + } + rcu_read_unlock(); +} + +static int iopt_pages_fill_from_domain(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + while (start_index != last_index + 1) { + unsigned long domain_last; + struct iopt_area *area; + + area = iopt_pages_find_domain_area(pages, start_index); + if (WARN_ON(!area)) + return -EINVAL; + + domain_last = min(iopt_area_last_index(area), last_index); + out_pages = raw_pages_from_domain(area->storage_domain, area, + start_index, domain_last, + out_pages); + start_index = domain_last + 1; + } + return 0; +} + +static int iopt_pages_fill_from_mm(struct iopt_pages *pages, + struct pfn_reader_user *user, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + unsigned long cur_index = start_index; + int rc; + + while (cur_index != last_index + 1) { + user->upages = out_pages + (cur_index - start_index); + rc = pfn_reader_user_pin(user, pages, cur_index, last_index); + if (rc) + goto out_unpin; + cur_index = user->upages_end; + } + return 0; + +out_unpin: + if (start_index != cur_index) + iopt_pages_err_unpin(pages, start_index, cur_index - 1, + out_pages); + return rc; +} + +/** + * iopt_pages_fill_xarray() - Read PFNs + * @pages: The pages to act on + * @start_index: The first page index in the range + * @last_index: The last page index in the range + * @out_pages: The output array to return the pages, may be NULL + * + * This populates the xarray and returns the pages in out_pages. As the slow + * path this is able to copy pages from other storage tiers into the xarray. + * + * On failure the xarray is left unchanged. + * + * This is part of the SW iommu interface to read pages for in-kernel use. + */ +int iopt_pages_fill_xarray(struct iopt_pages *pages, unsigned long start_index, + unsigned long last_index, struct page **out_pages) +{ + struct interval_tree_double_span_iter span; + unsigned long xa_end = start_index; + struct pfn_reader_user user; + int rc; + + pfn_reader_user_init(&user, pages); + user.upages_len = last_index - start_index + 1; + interval_tree_for_each_double_span(&span, &pages->access_itree, + &pages->domains_itree, start_index, + last_index) { + struct page **cur_pages; + + if (span.is_used == 1) { + cur_pages = out_pages + (span.start_used - start_index); + iopt_pages_fill_from_xarray(pages, span.start_used, + span.last_used, cur_pages); + continue; + } + + if (span.is_used == 2) { + cur_pages = out_pages + (span.start_used - start_index); + iopt_pages_fill_from_domain(pages, span.start_used, + span.last_used, cur_pages); + rc = pages_to_xarray(&pages->pinned_pfns, + span.start_used, span.last_used, + cur_pages); + if (rc) + goto out_clean_xa; + xa_end = span.last_used + 1; + continue; + } + + /* hole */ + cur_pages = out_pages + (span.start_hole - start_index); + rc = iopt_pages_fill_from_mm(pages, &user, span.start_hole, + span.last_hole, cur_pages); + if (rc) + goto out_clean_xa; + rc = pages_to_xarray(&pages->pinned_pfns, span.start_hole, + span.last_hole, cur_pages); + if (rc) { + iopt_pages_err_unpin(pages, span.start_hole, + span.last_hole, cur_pages); + goto out_clean_xa; + } + xa_end = span.last_hole + 1; + } + rc = pfn_reader_user_update_pinned(&user, pages); + if (rc) + goto out_clean_xa; + user.upages = NULL; + pfn_reader_user_destroy(&user, pages); + return 0; + +out_clean_xa: + if (start_index != xa_end) + iopt_pages_unfill_xarray(pages, start_index, xa_end - 1); + user.upages = NULL; + pfn_reader_user_destroy(&user, pages); + return rc; +} + +/* + * This can do everything and is fully coherent with what a iommu_domain would + * see. + */ +static int iopt_pages_rw_slow(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, unsigned long offset, + void *data, unsigned long length, + unsigned int flags) +{ + struct pfn_reader pfns; + int rc; + + mutex_lock(&pages->mutex); + + rc = pfn_reader_first(&pfns, pages, start_index, last_index); + if (rc) + goto out_unlock; + + while (!pfn_reader_done(&pfns)) { + unsigned long done; + + done = batch_rw(&pfns.batch, data, offset, length, flags); + data += done; + length -= done; + offset = 0; + pfn_reader_unpin(&pfns); + + rc = pfn_reader_next(&pfns); + if (rc) + goto out_destroy; + } + if (WARN_ON(length != 0)) + rc = -EINVAL; +out_destroy: + pfn_reader_destroy(&pfns); +out_unlock: + mutex_unlock(&pages->mutex); + return rc; +} + +/* + * A medium speed path that still allows DMA decoherence, but doesn't do any + * memory allocations or interval tree searches. + */ +static int iopt_pages_rw_page(struct iopt_pages *pages, unsigned long index, + unsigned long offset, void *data, + unsigned long length, unsigned int flags) +{ + struct page *page = NULL; + int rc; + + if (!mmget_not_zero(pages->source_mm)) + return iopt_pages_rw_slow(pages, index, index, offset, data, + length, flags); + + mmap_read_lock(pages->source_mm); + rc = pin_user_pages_remote( + pages->source_mm, (uintptr_t)(pages->uptr + index * PAGE_SIZE), + 1, (flags & IOMMUFD_ACCESS_RW_WRITE) ? FOLL_WRITE : 0, &page, + NULL, NULL); + mmap_read_unlock(pages->source_mm); + if (rc != 1) { + if (WARN_ON(rc >= 0)) + rc = -EINVAL; + goto out_mmput; + } + copy_data_page(page, data, offset, length, flags); + unpin_user_page(page); + rc = 0; + +out_mmput: + mmput(pages->source_mm); + return rc; +} + +/** + * iopt_pages_rw_access - Copy to/from a linear slice of the pages + * @pages: pages to act on + * @start_byte: First byte of pages to copy to/from + * @data: Kernel buffer to get/put the data + * @length: Number of bytes to copy + * @flags: IOMMUFD_ACCESS_RW_* flags + * + * This will find each page in the range, kmap it and then memcpy to/from + * the given kernel buffer. + */ +int iopt_pages_rw_access(struct iopt_pages *pages, unsigned long start_byte, + void *data, unsigned long length, unsigned int flags) +{ + unsigned long start_index = start_byte / PAGE_SIZE; + unsigned long last_index = (start_byte + length - 1) / PAGE_SIZE; + bool change_mm = current->mm != pages->source_mm; + int rc = 0; + + if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable) + return -EPERM; + + if (!(flags & IOMMUFD_ACCESS_RW_KTHREAD) && change_mm) { + if (start_index == last_index) + return iopt_pages_rw_page(pages, start_index, + start_byte % PAGE_SIZE, data, + length, flags); + return iopt_pages_rw_slow(pages, start_index, last_index, + start_byte % PAGE_SIZE, data, length, + flags); + } + + /* + * Try to copy using copy_to_user(). We do this as a fast path and + * ignore any pinning decoherence, unlike a real DMA path. + */ + if (change_mm) { + if (!mmget_not_zero(pages->source_mm)) + return iopt_pages_rw_slow(pages, start_index, + last_index, + start_byte % PAGE_SIZE, data, + length, flags); + kthread_use_mm(pages->source_mm); + } + + if (flags & IOMMUFD_ACCESS_RW_WRITE) { + if (copy_to_user(pages->uptr + start_byte, data, length)) + rc = -EFAULT; + } else { + if (copy_from_user(data, pages->uptr + start_byte, length)) + rc = -EFAULT; + } + + if (change_mm) { + kthread_unuse_mm(pages->source_mm); + mmput(pages->source_mm); + } + + return rc; +} + +static struct iopt_pages_access * +iopt_pages_get_exact_access(struct iopt_pages *pages, unsigned long index, + unsigned long last) +{ + struct interval_tree_node *node; + + lockdep_assert_held(&pages->mutex); + + /* There can be overlapping ranges in this interval tree */ + for (node = interval_tree_iter_first(&pages->access_itree, index, last); + node; node = interval_tree_iter_next(node, index, last)) + if (node->start == index && node->last == last) + return container_of(node, struct iopt_pages_access, + node); + return NULL; +} + +/** + * iopt_pages_add_access() - Record an in-knerel access for PFNs + * @pages: The source of PFNs + * @start_index: First page index + * @last_index: Inclusive last page index + * @out_pages: Output list of struct page's representing the PFNs + * @flags: IOMMUFD_ACCESS_RW_* flags + * + * Record that an in-kernel access will be accessing the pages, ensure they are + * pinned, and return the PFNs as a simple list of 'struct page *'. + * + * This should be undone through a matching call to iopt_pages_remove_access() + */ +int iopt_pages_add_access(struct iopt_pages *pages, unsigned long start_index, + unsigned long last_index, struct page **out_pages, + unsigned int flags) +{ + struct iopt_pages_access *access; + int rc; + + if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable) + return -EPERM; + + access = iopt_pages_get_exact_access(pages, start_index, last_index); + if (access) { + refcount_inc(&access->refcount); + iopt_pages_fill_from_xarray(pages, start_index, last_index, + out_pages); + return 0; + } + + access = kzalloc(sizeof(*access), GFP_KERNEL_ACCOUNT); + if (!access) + return -ENOMEM; + + rc = iopt_pages_fill_xarray(pages, start_index, last_index, out_pages); + if (rc) + goto out_free; + + access->node.start = start_index; + access->node.last = last_index; + refcount_set(&access->refcount, 1); + interval_tree_insert(&access->node, &pages->access_itree); + return 0; + +out_free: + kfree(access); + return rc; +} + +/** + * iopt_pages_remove_access() - Release an in-kernel access for PFNs + * @area: The source of PFNs + * @start_index: First page index + * @last_index: Inclusive last page index + * + * Undo iopt_pages_add_access() and unpin the pages if necessary. The caller + * must stop using the PFNs before calling this. + */ +void iopt_pages_remove_access(struct iopt_area *area, unsigned long start_index, + unsigned long last_index) +{ + struct iopt_pages_access *access; + struct iopt_pages *pages = area->pages; + + mutex_lock(&pages->mutex); + access = iopt_pages_get_exact_access(pages, start_index, last_index); + if (WARN_ON(!access)) + goto out_unlock; + + WARN_ON(area->num_accesses == 0); + area->num_accesses--; + + if (!refcount_dec_and_test(&access->refcount)) + goto out_unlock; + + interval_tree_remove(&access->node, &pages->access_itree); + iopt_pages_unfill_xarray(pages, start_index, last_index); + kfree(access); +out_unlock: + mutex_unlock(&pages->mutex); +}

This is the remainder of the IOAS data structure. Provide an object called an io_pagetable that is composed of iopt_areas pointing at iopt_pages, along with a list of iommu_domains that mirror the IOVA to PFN map.

At the top this is a simple interval tree of iopt_areas indicating the map of IOVA to iopt_pages. An xarray keeps track of a list of domains. Based on the attached domains there is a minimum alignment for areas (which may be smaller than PAGE_SIZE), an interval tree of reserved IOVA that can't be mapped and an IOVA of allowed IOVA that can always be mappable.

The concept of an 'access' refers to something like a VFIO mdev that is accessing the IOVA and using a 'struct page *' for CPU based access.

Externally an API is provided that matches the requirements of the IOCTL interface for map/unmap and domain attachment.

The API provides a 'copy' primitive to establish a new IOVA map in a different IOAS from an existing mapping by re-using the iopt_pages. This is the basic mechanism to provide single pinning.

This is designed to support a pre-registration flow where userspace would setup an dummy IOAS with no domains, map in memory and then establish an access to pin all PFNs into the xarray.

Copy can then be used to create new IOVA mappings in a different IOAS, with iommu_domains attached. Upon copy the PFNs will be read out of the xarray and mapped into the iommu_domains, avoiding any pin_user_pages() overheads.

Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Yi Liu yi.l.liu@intel.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com --- .clang-format | 1 + drivers/iommu/iommufd/Makefile | 1 + drivers/iommu/iommufd/io_pagetable.c | 1130 +++++++++++++++++++++++ drivers/iommu/iommufd/io_pagetable.h | 58 ++ drivers/iommu/iommufd/iommufd_private.h | 43 + 5 files changed, 1233 insertions(+) create mode 100644 drivers/iommu/iommufd/io_pagetable.c

diff --git a/.clang-format b/.clang-format index 501241f8977664..78aba4a10b1bbc 100644 --- a/.clang-format +++ b/.clang-format @@ -444,6 +444,7 @@ ForEachMacros: - 'interval_tree_for_each_span' - 'intlist__for_each_entry' - 'intlist__for_each_entry_safe' + - 'iopt_for_each_contig_area' - 'kcore_copy__for_each_phdr' - 'key_for_each' - 'key_for_each_safe' diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile index 05a0e91e30afad..b66a8c47ff55ec 100644 --- a/drivers/iommu/iommufd/Makefile +++ b/drivers/iommu/iommufd/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only iommufd-y := \ + io_pagetable.o \ main.o \ pages.o

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c new file mode 100644 index 00000000000000..27cbb652ee33cd --- /dev/null +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -0,0 +1,1130 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES. + * + * The io_pagetable is the top of datastructure that maps IOVA's to PFNs. The + * PFNs can be placed into an iommu_domain, or returned to the caller as a page + * list for access by an in-kernel user. + * + * The datastructure uses the iopt_pages to optimize the storage of the PFNs + * between the domains and xarray. + */ +#include <linux/iommufd.h> +#include <linux/lockdep.h> +#include <linux/iommu.h> +#include <linux/sched/mm.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/errno.h> + +#include "io_pagetable.h" + +struct iopt_pages_list { + struct iopt_pages *pages; + struct iopt_area *area; + struct list_head next; + unsigned long start_byte; + unsigned long length; +}; + +struct iopt_area *iopt_area_contig_init(struct iopt_area_contig_iter *iter, + struct io_pagetable *iopt, + unsigned long iova, + unsigned long last_iova) +{ + lockdep_assert_held(&iopt->iova_rwsem); + + iter->cur_iova = iova; + iter->last_iova = last_iova; + iter->area = iopt_area_iter_first(iopt, iova, last_iova); + if (!iter->area) + return NULL; + if (!iter->area->pages) { + iter->area = NULL; + return NULL; + } + return iter->area; +} + +struct iopt_area *iopt_area_contig_next(struct iopt_area_contig_iter *iter) +{ + unsigned long last_iova; + + if (!iter->area) + return NULL; + last_iova = iopt_area_last_iova(iter->area); + if (iter->last_iova <= last_iova) + return NULL; + + iter->cur_iova = last_iova + 1; + iter->area = iopt_area_iter_next(iter->area, iter->cur_iova, + iter->last_iova); + if (!iter->area) + return NULL; + if (iter->cur_iova != iopt_area_iova(iter->area) || + !iter->area->pages) { + iter->area = NULL; + return NULL; + } + return iter->area; +} + +static bool __alloc_iova_check_hole(struct interval_tree_span_iter *span, + unsigned long length, + unsigned long iova_alignment, + unsigned long page_offset) +{ + if (!span->is_hole || span->last_hole - span->start_hole < length - 1) + return false; + + span->start_hole = ALIGN(span->start_hole, iova_alignment) | + page_offset; + if (span->start_hole > span->last_hole || + span->last_hole - span->start_hole < length - 1) + return false; + return true; +} + +static bool __alloc_iova_check_used(struct interval_tree_span_iter *span, + unsigned long length, + unsigned long iova_alignment, + unsigned long page_offset) +{ + if (span->is_hole || span->last_used - span->start_used < length - 1) + return false; + + span->start_used = ALIGN(span->start_used, iova_alignment) | + page_offset; + if (span->start_used > span->last_used || + span->last_used - span->start_used < length - 1) + return false; + return true; +} + +/* + * Automatically find a block of IOVA that is not being used and not reserved. + * Does not return a 0 IOVA even if it is valid. + */ +static int iopt_alloc_iova(struct io_pagetable *iopt, unsigned long *iova, + unsigned long uptr, unsigned long length) +{ + struct interval_tree_span_iter reserved_span; + unsigned long page_offset = uptr % PAGE_SIZE; + struct interval_tree_span_iter allowed_span; + struct interval_tree_span_iter area_span; + unsigned long iova_alignment; + + lockdep_assert_held(&iopt->iova_rwsem); + + /* Protect roundup_pow-of_two() from overflow */ + if (length == 0 || length >= ULONG_MAX / 2) + return -EOVERFLOW; + + /* + * Keep alignment present in the uptr when building the IOVA, this + * increases the chance we can map a THP. + */ + if (!uptr) + iova_alignment = roundup_pow_of_two(length); + else + iova_alignment = min_t(unsigned long, + roundup_pow_of_two(length), + 1UL << __ffs64(uptr)); + + if (iova_alignment < iopt->iova_alignment) + return -EINVAL; + + interval_tree_for_each_span(&allowed_span, &iopt->allowed_itree, + PAGE_SIZE, ULONG_MAX - PAGE_SIZE) { + if (RB_EMPTY_ROOT(&iopt->allowed_itree.rb_root)) { + allowed_span.start_used = PAGE_SIZE; + allowed_span.last_used = ULONG_MAX - PAGE_SIZE; + allowed_span.is_hole = false; + } + + if (!__alloc_iova_check_used(&allowed_span, length, + iova_alignment, page_offset)) + continue; + + interval_tree_for_each_span(&area_span, &iopt->area_itree, + allowed_span.start_used, + allowed_span.last_used) { + if (!__alloc_iova_check_hole(&area_span, length, + iova_alignment, + page_offset)) + continue; + + interval_tree_for_each_span(&reserved_span, + &iopt->reserved_itree, + area_span.start_used, + area_span.last_used) { + if (!__alloc_iova_check_hole( + &reserved_span, length, + iova_alignment, page_offset)) + continue; + + *iova = reserved_span.start_hole; + return 0; + } + } + } + return -ENOSPC; +} + +static int iopt_check_iova(struct io_pagetable *iopt, unsigned long iova, + unsigned long length) +{ + unsigned long last; + + lockdep_assert_held(&iopt->iova_rwsem); + + if ((iova & (iopt->iova_alignment - 1)) || + (length & (iopt->iova_alignment - 1)) || !length) + return -EINVAL; + + if (check_add_overflow(iova, length - 1, &last)) + return -EOVERFLOW; + + /* No reserved IOVA intersects the range */ + if (iopt_reserved_iter_first(iopt, iova, last)) + return -ENOENT; + + /* Check that there is not already a mapping in the range */ + if (iopt_area_iter_first(iopt, iova, last)) + return -EADDRINUSE; + return 0; +} + +/* + * The area takes a slice of the pages from start_bytes to start_byte + length + */ +static int iopt_insert_area(struct io_pagetable *iopt, struct iopt_area *area, + struct iopt_pages *pages, unsigned long iova, + unsigned long start_byte, unsigned long length, + int iommu_prot) +{ + lockdep_assert_held_write(&iopt->iova_rwsem); + + if ((iommu_prot & IOMMU_WRITE) && !pages->writable) + return -EPERM; + + area->iommu_prot = iommu_prot; + area->page_offset = start_byte % PAGE_SIZE; + if (area->page_offset & (iopt->iova_alignment - 1)) + return -EINVAL; + + area->node.start = iova; + if (check_add_overflow(iova, length - 1, &area->node.last)) + return -EOVERFLOW; + + area->pages_node.start = start_byte / PAGE_SIZE; + if (check_add_overflow(start_byte, length - 1, &area->pages_node.last)) + return -EOVERFLOW; + area->pages_node.last = area->pages_node.last / PAGE_SIZE; + if (WARN_ON(area->pages_node.last >= pages->npages)) + return -EOVERFLOW; + + /* + * The area is inserted with a NULL pages indicating it is not fully + * initialized yet. + */ + area->iopt = iopt; + interval_tree_insert(&area->node, &iopt->area_itree); + return 0; +} + +static int iopt_alloc_area_pages(struct io_pagetable *iopt, + struct list_head *pages_list, + unsigned long length, unsigned long *dst_iova, + int iommu_prot, unsigned int flags) +{ + struct iopt_pages_list *elm; + unsigned long iova; + int rc = 0; + + list_for_each_entry(elm, pages_list, next) { + elm->area = kzalloc(sizeof(*elm->area), GFP_KERNEL_ACCOUNT); + if (!elm->area) + return -ENOMEM; + } + + down_write(&iopt->iova_rwsem); + if (flags & IOPT_ALLOC_IOVA) { + /* Use the first entry to guess the ideal IOVA alignment */ + elm = list_first_entry(pages_list, struct iopt_pages_list, + next); + rc = iopt_alloc_iova( + iopt, dst_iova, + (uintptr_t)elm->pages->uptr + elm->start_byte, length); + if (rc) + goto out_unlock; + } else { + rc = iopt_check_iova(iopt, *dst_iova, length); + if (rc) + goto out_unlock; + } + + /* + * Areas are created with a NULL pages so that the IOVA space is + * reserved and we can unlock the iova_rwsem. + */ + iova = *dst_iova; + list_for_each_entry(elm, pages_list, next) { + rc = iopt_insert_area(iopt, elm->area, elm->pages, iova, + elm->start_byte, elm->length, iommu_prot); + if (rc) + goto out_unlock; + iova += elm->length; + } + +out_unlock: + up_write(&iopt->iova_rwsem); + return rc; +} + +static void iopt_abort_area(struct iopt_area *area) +{ + if (area->iopt) { + down_write(&area->iopt->iova_rwsem); + interval_tree_remove(&area->node, &area->iopt->area_itree); + up_write(&area->iopt->iova_rwsem); + } + kfree(area); +} + +void iopt_free_pages_list(struct list_head *pages_list) +{ + struct iopt_pages_list *elm; + + while ((elm = list_first_entry_or_null(pages_list, + struct iopt_pages_list, next))) { + if (elm->area) + iopt_abort_area(elm->area); + if (elm->pages) + iopt_put_pages(elm->pages); + list_del(&elm->next); + kfree(elm); + } +} + +static int iopt_fill_domains_pages(struct list_head *pages_list) +{ + struct iopt_pages_list *undo_elm; + struct iopt_pages_list *elm; + int rc; + + list_for_each_entry(elm, pages_list, next) { + rc = iopt_area_fill_domains(elm->area, elm->pages); + if (rc) + goto err_undo; + } + return 0; + +err_undo: + list_for_each_entry(undo_elm, pages_list, next) { + if (undo_elm == elm) + break; + iopt_area_unfill_domains(undo_elm->area, undo_elm->pages); + } + return rc; +} + +int iopt_map_pages(struct io_pagetable *iopt, struct list_head *pages_list, + unsigned long length, unsigned long *dst_iova, + int iommu_prot, unsigned int flags) +{ + struct iopt_pages_list *elm; + int rc; + + rc = iopt_alloc_area_pages(iopt, pages_list, length, dst_iova, + iommu_prot, flags); + if (rc) + return rc; + + down_read(&iopt->domains_rwsem); + rc = iopt_fill_domains_pages(pages_list); + if (rc) + goto out_unlock_domains; + + down_write(&iopt->iova_rwsem); + list_for_each_entry(elm, pages_list, next) { + /* + * area->pages must be set inside the domains_rwsem to ensure + * any newly added domains will get filled. Moves the reference + * in from the list. + */ + elm->area->pages = elm->pages; + elm->pages = NULL; + elm->area = NULL; + } + up_write(&iopt->iova_rwsem); +out_unlock_domains: + up_read(&iopt->domains_rwsem); + return rc; +} + +/** + * iopt_map_user_pages() - Map a user VA to an iova in the io page table + * @iopt: io_pagetable to act on + * @iova: If IOPT_ALLOC_IOVA is set this is unused on input and contains + * the chosen iova on output. Otherwise is the iova to map to on input + * @uptr: User VA to map + * @length: Number of bytes to map + * @iommu_prot: Combination of IOMMU_READ/WRITE/etc bits for the mapping + * @flags: IOPT_ALLOC_IOVA or zero + * + * iova, uptr, and length must be aligned to iova_alignment. For domain backed + * page tables this will pin the pages and load them into the domain at iova. + * For non-domain page tables this will only setup a lazy reference and the + * caller must use iopt_access_pages() to touch them. + * + * iopt_unmap_iova() must be called to undo this before the io_pagetable can be + * destroyed. + */ +int iopt_map_user_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, + unsigned long *iova, void __user *uptr, + unsigned long length, int iommu_prot, + unsigned int flags) +{ + struct iopt_pages_list elm; + LIST_HEAD(pages_list); + int rc; + + elm.pages = iopt_alloc_pages(uptr, length, iommu_prot & IOMMU_WRITE); + if (IS_ERR(elm.pages)) + return PTR_ERR(elm.pages); + if (ictx->account_mode == IOPT_PAGES_ACCOUNT_MM && + elm.pages->account_mode == IOPT_PAGES_ACCOUNT_USER) + elm.pages->account_mode = IOPT_PAGES_ACCOUNT_MM; + elm.start_byte = uptr - elm.pages->uptr; + elm.length = length; + list_add(&elm.next, &pages_list); + + rc = iopt_map_pages(iopt, &pages_list, length, iova, iommu_prot, flags); + if (rc) { + if (elm.area) + iopt_abort_area(elm.area); + if (elm.pages) + iopt_put_pages(elm.pages); + return rc; + } + return 0; +} + +int iopt_get_pages(struct io_pagetable *iopt, unsigned long iova, + unsigned long length, struct list_head *pages_list) +{ + struct iopt_area_contig_iter iter; + unsigned long last_iova; + struct iopt_area *area; + int rc; + + if (!length) + return -EINVAL; + if (check_add_overflow(iova, length - 1, &last_iova)) + return -EOVERFLOW; + + down_read(&iopt->iova_rwsem); + iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) { + struct iopt_pages_list *elm; + unsigned long last = min(last_iova, iopt_area_last_iova(area)); + + elm = kzalloc(sizeof(*elm), GFP_KERNEL_ACCOUNT); + if (!elm) { + rc = -ENOMEM; + goto err_free; + } + elm->start_byte = iopt_area_start_byte(area, iter.cur_iova); + elm->pages = area->pages; + elm->length = (last - iter.cur_iova) + 1; + kref_get(&elm->pages->kref); + list_add_tail(&elm->next, pages_list); + } + if (!iopt_area_contig_done(&iter)) { + rc = -ENOENT; + goto err_free; + } + up_read(&iopt->iova_rwsem); + return 0; +err_free: + up_read(&iopt->iova_rwsem); + iopt_free_pages_list(pages_list); + return rc; +} + +static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start, + unsigned long end, unsigned long *unmapped) +{ + struct iopt_area *area; + unsigned long unmapped_bytes = 0; + int rc = -ENOENT; + + /* + * The domains_rwsem must be held in read mode any time any area->pages + * is NULL. This prevents domain attach/detatch from running + * concurrently with cleaning up the area. + */ + down_read(&iopt->domains_rwsem); + down_write(&iopt->iova_rwsem); + while ((area = iopt_area_iter_first(iopt, start, end))) { + unsigned long area_last = iopt_area_last_iova(area); + unsigned long area_first = iopt_area_iova(area); + struct iopt_pages *pages; + + /* Userspace should not race map/unmap's of the same area */ + if (!area->pages) { + rc = -EBUSY; + goto out_unlock_iova; + } + + if (area_first < start || area_last > end) { + rc = -ENOENT; + goto out_unlock_iova; + } + + /* + * num_accesses writers must hold the iova_rwsem too, so we can + * safely read it under the write side of the iovam_rwsem + * without the pages->mutex. + */ + if (area->num_accesses) { + start = area_first; + area->prevent_access = true; + up_write(&iopt->iova_rwsem); + up_read(&iopt->domains_rwsem); + /* Later patch calls back to drivers to unmap */ + return -EBUSY; + } + + pages = area->pages; + area->pages = NULL; + up_write(&iopt->iova_rwsem); + + iopt_area_unfill_domains(area, pages); + iopt_abort_area(area); + iopt_put_pages(pages); + + unmapped_bytes += area_last - area_first + 1; + + down_write(&iopt->iova_rwsem); + } + if (unmapped_bytes) + rc = 0; + +out_unlock_iova: + up_write(&iopt->iova_rwsem); + up_read(&iopt->domains_rwsem); + if (unmapped) + *unmapped = unmapped_bytes; + return rc; +} + +/** + * iopt_unmap_iova() - Remove a range of iova + * @iopt: io_pagetable to act on + * @iova: Starting iova to unmap + * @length: Number of bytes to unmap + * @unmapped: Return number of bytes unmapped + * + * The requested range must be a superset of existing ranges. + * Splitting/truncating IOVA mappings is not allowed. + */ +int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova, + unsigned long length, unsigned long *unmapped) +{ + unsigned long iova_end; + + if (!length) + return -EINVAL; + + if (check_add_overflow(iova, length - 1, &iova_end)) + return -EOVERFLOW; + + return iopt_unmap_iova_range(iopt, iova, iova_end, unmapped); +} + +int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped) +{ + return iopt_unmap_iova_range(iopt, 0, ULONG_MAX, unmapped); +} + +/* The caller must always free all the nodes in the allowed_iova rb_root. */ +int iopt_set_allow_iova(struct io_pagetable *iopt, + struct rb_root_cached *allowed_iova) +{ + struct iopt_allowed *allowed; + + down_write(&iopt->iova_rwsem); + swap(*allowed_iova, iopt->allowed_itree); + + for (allowed = iopt_allowed_iter_first(iopt, 0, ULONG_MAX); allowed; + allowed = iopt_allowed_iter_next(allowed, 0, ULONG_MAX)) { + if (iopt_reserved_iter_first(iopt, allowed->node.start, + allowed->node.last)) { + swap(*allowed_iova, iopt->allowed_itree); + up_write(&iopt->iova_rwsem); + return -EADDRINUSE; + } + } + up_write(&iopt->iova_rwsem); + return 0; +} + +int iopt_reserve_iova(struct io_pagetable *iopt, unsigned long start, + unsigned long last, void *owner) +{ + struct iopt_reserved *reserved; + + lockdep_assert_held_write(&iopt->iova_rwsem); + + if (iopt_area_iter_first(iopt, start, last) || + iopt_allowed_iter_first(iopt, start, last)) + return -EADDRINUSE; + + reserved = kzalloc(sizeof(*reserved), GFP_KERNEL_ACCOUNT); + if (!reserved) + return -ENOMEM; + reserved->node.start = start; + reserved->node.last = last; + reserved->owner = owner; + interval_tree_insert(&reserved->node, &iopt->reserved_itree); + return 0; +} + +static void __iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner) +{ + struct iopt_reserved *reserved, *next; + + lockdep_assert_held_write(&iopt->iova_rwsem); + + for (reserved = iopt_reserved_iter_first(iopt, 0, ULONG_MAX); reserved; + reserved = next) { + next = iopt_reserved_iter_next(reserved, 0, ULONG_MAX); + + if (reserved->owner == owner) { + interval_tree_remove(&reserved->node, + &iopt->reserved_itree); + kfree(reserved); + } + } +} + +void iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner) +{ + down_write(&iopt->iova_rwsem); + __iopt_remove_reserved_iova(iopt, owner); + up_write(&iopt->iova_rwsem); +} + +int iopt_init_table(struct io_pagetable *iopt) +{ + init_rwsem(&iopt->iova_rwsem); + init_rwsem(&iopt->domains_rwsem); + iopt->area_itree = RB_ROOT_CACHED; + iopt->allowed_itree = RB_ROOT_CACHED; + iopt->reserved_itree = RB_ROOT_CACHED; + xa_init_flags(&iopt->domains, XA_FLAGS_ACCOUNT); + + /* + * iopt's start as SW tables that can use the entire size_t IOVA space + * due to the use of size_t in the APIs. They have no alignment + * restriction. + */ + iopt->iova_alignment = 1; + + return 0; +} + +void iopt_destroy_table(struct io_pagetable *iopt) +{ + struct interval_tree_node *node; + + while ((node = interval_tree_iter_first(&iopt->allowed_itree, 0, + ULONG_MAX))) { + interval_tree_remove(node, &iopt->allowed_itree); + kfree(container_of(node, struct iopt_allowed, node)); + } + + WARN_ON(!RB_EMPTY_ROOT(&iopt->reserved_itree.rb_root)); + WARN_ON(!xa_empty(&iopt->domains)); + WARN_ON(!RB_EMPTY_ROOT(&iopt->area_itree.rb_root)); +} + +/** + * iopt_unfill_domain() - Unfill a domain with PFNs + * @iopt: io_pagetable to act on + * @domain: domain to unfill + * + * This is used when removing a domain from the iopt. Every area in the iopt + * will be unmapped from the domain. The domain must already be removed from the + * domains xarray. + */ +static void iopt_unfill_domain(struct io_pagetable *iopt, + struct iommu_domain *domain) +{ + struct iopt_area *area; + + lockdep_assert_held(&iopt->iova_rwsem); + lockdep_assert_held_write(&iopt->domains_rwsem); + + /* + * Some other domain is holding all the pfns still, rapidly unmap this + * domain. + */ + if (iopt->next_domain_id != 0) { + /* Pick an arbitrary remaining domain to act as storage */ + struct iommu_domain *storage_domain = + xa_load(&iopt->domains, 0); + + for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area; + area = iopt_area_iter_next(area, 0, ULONG_MAX)) { + struct iopt_pages *pages = area->pages; + + if (!pages) + continue; + + mutex_lock(&pages->mutex); + if (area->storage_domain != domain) { + mutex_unlock(&pages->mutex); + continue; + } + area->storage_domain = storage_domain; + mutex_unlock(&pages->mutex); + } + + iopt_unmap_domain(iopt, domain); + return; + } + + for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area; + area = iopt_area_iter_next(area, 0, ULONG_MAX)) { + struct iopt_pages *pages = area->pages; + + if (!pages) + continue; + + mutex_lock(&pages->mutex); + interval_tree_remove(&area->pages_node, &pages->domains_itree); + WARN_ON(area->storage_domain != domain); + area->storage_domain = NULL; + iopt_area_unfill_domain(area, pages, domain); + mutex_unlock(&pages->mutex); + } +} + +/** + * iopt_fill_domain() - Fill a domain with PFNs + * @iopt: io_pagetable to act on + * @domain: domain to fill + * + * Fill the domain with PFNs from every area in the iopt. On failure the domain + * is left unchanged. + */ +static int iopt_fill_domain(struct io_pagetable *iopt, + struct iommu_domain *domain) +{ + struct iopt_area *end_area; + struct iopt_area *area; + int rc; + + lockdep_assert_held(&iopt->iova_rwsem); + lockdep_assert_held_write(&iopt->domains_rwsem); + + for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area; + area = iopt_area_iter_next(area, 0, ULONG_MAX)) { + struct iopt_pages *pages = area->pages; + + if (!pages) + continue; + + mutex_lock(&pages->mutex); + rc = iopt_area_fill_domain(area, domain); + if (rc) { + mutex_unlock(&pages->mutex); + goto out_unfill; + } + if (!area->storage_domain) { + WARN_ON(iopt->next_domain_id != 0); + area->storage_domain = domain; + interval_tree_insert(&area->pages_node, + &pages->domains_itree); + } + mutex_unlock(&pages->mutex); + } + return 0; + +out_unfill: + end_area = area; + for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area; + area = iopt_area_iter_next(area, 0, ULONG_MAX)) { + struct iopt_pages *pages = area->pages; + + if (area == end_area) + break; + if (!pages) + continue; + mutex_lock(&pages->mutex); + if (iopt->next_domain_id == 0) { + interval_tree_remove(&area->pages_node, + &pages->domains_itree); + area->storage_domain = NULL; + } + iopt_area_unfill_domain(area, pages, domain); + mutex_unlock(&pages->mutex); + } + return rc; +} + +/* All existing area's conform to an increased page size */ +static int iopt_check_iova_alignment(struct io_pagetable *iopt, + unsigned long new_iova_alignment) +{ + struct iopt_area *area; + + lockdep_assert_held(&iopt->iova_rwsem); + + for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area; + area = iopt_area_iter_next(area, 0, ULONG_MAX)) + if ((iopt_area_iova(area) % new_iova_alignment) || + (iopt_area_length(area) % new_iova_alignment)) + return -EADDRINUSE; + return 0; +} + +int iopt_table_add_domain(struct io_pagetable *iopt, + struct iommu_domain *domain) +{ + const struct iommu_domain_geometry *geometry = &domain->geometry; + struct iommu_domain *iter_domain; + unsigned int new_iova_alignment; + unsigned long index; + int rc; + + down_write(&iopt->domains_rwsem); + down_write(&iopt->iova_rwsem); + + xa_for_each(&iopt->domains, index, iter_domain) { + if (WARN_ON(iter_domain == domain)) { + rc = -EEXIST; + goto out_unlock; + } + } + + /* + * The io page size drives the iova_alignment. Internally the iopt_pages + * works in PAGE_SIZE units and we adjust when mapping sub-PAGE_SIZE + * objects into the iommu_domain. + * + * A iommu_domain must always be able to accept PAGE_SIZE to be + * compatible as we can't guarantee higher contiguity. + */ + new_iova_alignment = max_t(unsigned long, + 1UL << __ffs(domain->pgsize_bitmap), + iopt->iova_alignment); + if (new_iova_alignment > PAGE_SIZE) { + rc = -EINVAL; + goto out_unlock; + } + if (new_iova_alignment != iopt->iova_alignment) { + rc = iopt_check_iova_alignment(iopt, new_iova_alignment); + if (rc) + goto out_unlock; + } + + /* No area exists that is outside the allowed domain aperture */ + if (geometry->aperture_start != 0) { + rc = iopt_reserve_iova(iopt, 0, geometry->aperture_start - 1, + domain); + if (rc) + goto out_reserved; + } + if (geometry->aperture_end != ULONG_MAX) { + rc = iopt_reserve_iova(iopt, geometry->aperture_end + 1, + ULONG_MAX, domain); + if (rc) + goto out_reserved; + } + + rc = xa_reserve(&iopt->domains, iopt->next_domain_id, GFP_KERNEL); + if (rc) + goto out_reserved; + + rc = iopt_fill_domain(iopt, domain); + if (rc) + goto out_release; + + iopt->iova_alignment = new_iova_alignment; + xa_store(&iopt->domains, iopt->next_domain_id, domain, GFP_KERNEL); + iopt->next_domain_id++; + up_write(&iopt->iova_rwsem); + up_write(&iopt->domains_rwsem); + return 0; +out_release: + xa_release(&iopt->domains, iopt->next_domain_id); +out_reserved: + __iopt_remove_reserved_iova(iopt, domain); +out_unlock: + up_write(&iopt->iova_rwsem); + up_write(&iopt->domains_rwsem); + return rc; +} + +static bool iopt_calculate_iova_alignment(struct io_pagetable *iopt) +{ + unsigned long new_iova_alignment; + struct iommu_domain *domain; + unsigned long index; + + if (iopt->disable_large_pages) + new_iova_alignment = PAGE_SIZE; + else + new_iova_alignment = 1; + + xa_for_each(&iopt->domains, index, domain) + new_iova_alignment = max_t(unsigned long, + 1UL << __ffs(domain->pgsize_bitmap), + new_iova_alignment); + if (new_iova_alignment > iopt->iova_alignment) { + int rc; + + rc = iopt_check_iova_alignment(iopt, new_iova_alignment); + if (rc) + return -EADDRINUSE; + } + iopt->iova_alignment = new_iova_alignment; + return 0; +} + +void iopt_table_remove_domain(struct io_pagetable *iopt, + struct iommu_domain *domain) +{ + struct iommu_domain *iter_domain = NULL; + unsigned long index; + + down_write(&iopt->domains_rwsem); + down_write(&iopt->iova_rwsem); + + xa_for_each(&iopt->domains, index, iter_domain) + if (iter_domain == domain) + break; + if (WARN_ON(iter_domain != domain) || index >= iopt->next_domain_id) + goto out_unlock; + + /* + * Compress the xarray to keep it linear by swapping the entry to erase + * with the tail entry and shrinking the tail. + */ + iopt->next_domain_id--; + iter_domain = xa_erase(&iopt->domains, iopt->next_domain_id); + if (index != iopt->next_domain_id) + xa_store(&iopt->domains, index, iter_domain, GFP_KERNEL); + + iopt_unfill_domain(iopt, domain); + __iopt_remove_reserved_iova(iopt, domain); + + WARN_ON(iopt_calculate_iova_alignment(iopt)); +out_unlock: + up_write(&iopt->iova_rwsem); + up_write(&iopt->domains_rwsem); +} + +/** + * iopt_area_split - Split an area into two parts at iova + * @area: The area to split + * @iova: Becomes the last of a new area + * + * This splits an area into two. It is part of the VFIO compatibility to allow + * poking a hole in the mapping. The two areas continue to point at the same + * iopt_pages, just with different starting bytes. + */ +static int iopt_area_split(struct iopt_area *area, unsigned long iova) +{ + unsigned long alignment = area->iopt->iova_alignment; + unsigned long last_iova = iopt_area_last_iova(area); + unsigned long start_iova = iopt_area_iova(area); + unsigned long new_start = iova + 1; + struct io_pagetable *iopt = area->iopt; + struct iopt_pages *pages = area->pages; + struct iopt_area *lhs; + struct iopt_area *rhs; + int rc; + + lockdep_assert_held_write(&iopt->iova_rwsem); + + if (iova == start_iova || iova == last_iova) + return 0; + + if (!pages || area->prevent_access) + return -EBUSY; + + if (new_start & (alignment - 1) || + iopt_area_start_byte(area, new_start) & (alignment - 1)) + return -EINVAL; + + lhs = kzalloc(sizeof(*area), GFP_KERNEL_ACCOUNT); + if (!lhs) + return -ENOMEM; + + rhs = kzalloc(sizeof(*area), GFP_KERNEL_ACCOUNT); + if (!rhs) { + rc = -ENOMEM; + goto err_free_lhs; + } + + mutex_lock(&pages->mutex); + /* + * Splitting is not permitted if a domain could have been mapped with + * huge pages. + */ + if (area->storage_domain && !iopt->disable_large_pages) { + rc = -EINVAL; + goto err_unlock; + } + + interval_tree_remove(&area->node, &iopt->area_itree); + rc = iopt_insert_area(iopt, lhs, area->pages, start_iova, + iopt_area_start_byte(area, start_iova), + (new_start - 1) - start_iova + 1, + area->iommu_prot); + if (WARN_ON(rc)) + goto err_insert; + + rc = iopt_insert_area(iopt, rhs, area->pages, new_start, + iopt_area_start_byte(area, new_start), + last_iova - new_start + 1, area->iommu_prot); + if (WARN_ON(rc)) + goto err_remove_lhs; + + lhs->storage_domain = area->storage_domain; + lhs->num_accesses = area->num_accesses; + lhs->pages = area->pages; + rhs->storage_domain = area->storage_domain; + rhs->num_accesses = area->num_accesses; + rhs->pages = area->pages; + kref_get(&rhs->pages->kref); + kfree(area); + mutex_unlock(&pages->mutex); + + /* + * No change to domains or accesses because the pages hasn't been + * changed + */ + return 0; + +err_remove_lhs: + interval_tree_remove(&lhs->node, &iopt->area_itree); +err_insert: + interval_tree_insert(&area->node, &iopt->area_itree); +err_unlock: + mutex_unlock(&pages->mutex); + kfree(rhs); +err_free_lhs: + kfree(lhs); + return rc; +} + +int iopt_cut_iova(struct io_pagetable *iopt, unsigned long *iovas, + size_t num_iovas) +{ + int rc = 0; + int i; + + down_write(&iopt->iova_rwsem); + for (i = 0; i < num_iovas; i++) { + struct iopt_area *area; + + area = iopt_area_iter_first(iopt, iovas[i], iovas[i]); + if (!area) + continue; + rc = iopt_area_split(area, iovas[i]); + if (rc) + break; + } + up_write(&iopt->iova_rwsem); + return rc; +} + +void iopt_enable_large_pages(struct io_pagetable *iopt) +{ + down_write(&iopt->domains_rwsem); + down_write(&iopt->iova_rwsem); + WRITE_ONCE(iopt->disable_large_pages, false); + iopt_calculate_iova_alignment(iopt); + up_write(&iopt->iova_rwsem); + up_write(&iopt->domains_rwsem); +} + +int iopt_disable_large_pages(struct io_pagetable *iopt) +{ + int rc = 0; + + down_write(&iopt->domains_rwsem); + down_write(&iopt->iova_rwsem); + if (iopt->disable_large_pages) + goto out_unlock; + + /* Won't do it if domains already have pages mapped in them */ + if (!xa_empty(&iopt->domains) && + !RB_EMPTY_ROOT(&iopt->area_itree.rb_root)) { + rc = -EINVAL; + goto out_unlock; + } + + WRITE_ONCE(iopt->disable_large_pages, true); + rc = iopt_calculate_iova_alignment(iopt); + if (rc) + WRITE_ONCE(iopt->disable_large_pages, false); +out_unlock: + up_write(&iopt->iova_rwsem); + up_write(&iopt->domains_rwsem); + return rc; +} + +/* Narrow the valid_iova_itree to include reserved ranges from a group. */ +int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt, + struct device *device, + struct iommu_group *group, + phys_addr_t *sw_msi_start) +{ + struct iommu_resv_region *resv; + struct iommu_resv_region *tmp; + LIST_HEAD(group_resv_regions); + int rc; + + down_write(&iopt->iova_rwsem); + rc = iommu_get_group_resv_regions(group, &group_resv_regions); + if (rc) + goto out_unlock; + + list_for_each_entry(resv, &group_resv_regions, list) { + if (resv->type == IOMMU_RESV_DIRECT_RELAXABLE) + continue; + + /* + * The presence of any 'real' MSI regions should take precedence + * over the software-managed one if the IOMMU driver happens to + * advertise both types. + */ + if (sw_msi_start && resv->type == IOMMU_RESV_MSI) { + *sw_msi_start = 0; + sw_msi_start = NULL; + } + if (sw_msi_start && resv->type == IOMMU_RESV_SW_MSI) + *sw_msi_start = resv->start; + + rc = iopt_reserve_iova(iopt, resv->start, + resv->length - 1 + resv->start, device); + if (rc) + goto out_reserved; + } + rc = 0; + goto out_free_resv; + +out_reserved: + __iopt_remove_reserved_iova(iopt, device); +out_free_resv: + list_for_each_entry_safe(resv, tmp, &group_resv_regions, list) + kfree(resv); +out_unlock: + up_write(&iopt->iova_rwsem); + return rc; +} diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index 083451afcdcf46..0bd645da97809a 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -46,9 +46,19 @@ struct iopt_area { unsigned int page_offset; /* IOMMU_READ, IOMMU_WRITE, etc */ int iommu_prot; + bool prevent_access : 1; unsigned int num_accesses; };

+struct iopt_allowed { + struct interval_tree_node node; +}; + +struct iopt_reserved { + struct interval_tree_node node; + void *owner; +}; + int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages); void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages);

@@ -82,6 +92,27 @@ static inline size_t iopt_area_length(struct iopt_area *area) return (area->node.last - area->node.start) + 1; }

+/* + * Number of bytes from the start of the iopt_pages that the iova begins. + * iopt_area_start_byte() / PAGE_SIZE encodes the starting page index + * iopt_area_start_byte() % PAGE_SIZE encodes the offset within that page + */ +static inline unsigned long iopt_area_start_byte(struct iopt_area *area, + unsigned long iova) +{ + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(iova < iopt_area_iova(area) || + iova > iopt_area_last_iova(area)); + return (iova - iopt_area_iova(area)) + area->page_offset + + iopt_area_index(area) * PAGE_SIZE; +} + +static inline unsigned long iopt_area_iova_to_index(struct iopt_area *area, + unsigned long iova) +{ + return iopt_area_start_byte(area, iova) / PAGE_SIZE; +} + #define __make_iopt_iter(name) \ static inline struct iopt_##name *iopt_##name##_iter_first( \ struct io_pagetable *iopt, unsigned long start, \ @@ -109,6 +140,33 @@ static inline size_t iopt_area_length(struct iopt_area *area) }

__make_iopt_iter(area) +__make_iopt_iter(allowed) +__make_iopt_iter(reserved) + +struct iopt_area_contig_iter { + unsigned long cur_iova; + unsigned long last_iova; + struct iopt_area *area; +}; +struct iopt_area *iopt_area_contig_init(struct iopt_area_contig_iter *iter, + struct io_pagetable *iopt, + unsigned long iova, + unsigned long last_iova); +struct iopt_area *iopt_area_contig_next(struct iopt_area_contig_iter *iter); + +static inline bool iopt_area_contig_done(struct iopt_area_contig_iter *iter) +{ + return iter->area && iter->last_iova <= iopt_area_last_iova(iter->area); +} + +/* + * Iterate over a contiguous list of areas that span the iova,last_iova range. + * The caller must check iopt_area_contig_done() after the loop to see if + * contiguous areas existed. + */ +#define iopt_for_each_contig_area(iter, area, iopt, iova, last_iova) \ + for (area = iopt_area_contig_init(iter, iopt, iova, last_iova); area; \ + area = iopt_area_contig_next(iter))

enum { IOPT_PAGES_ACCOUNT_NONE = 0, diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index d814ca2c4cd312..ba8ecdc209ab6e 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -9,9 +9,14 @@ #include <linux/refcount.h> #include <linux/uaccess.h>

+struct iommu_domain; +struct iommu_group; + struct iommufd_ctx { struct file *file; struct xarray objects; + + u8 account_mode; };

/* @@ -36,8 +41,46 @@ struct io_pagetable { /* IOVA that cannot be allocated, struct iopt_reserved */ struct rb_root_cached reserved_itree; u8 disable_large_pages; + unsigned long iova_alignment; };

+int iopt_init_table(struct io_pagetable *iopt); +void iopt_destroy_table(struct io_pagetable *iopt); +int iopt_get_pages(struct io_pagetable *iopt, unsigned long iova, + unsigned long length, struct list_head *pages_list); +void iopt_free_pages_list(struct list_head *pages_list); +enum { + IOPT_ALLOC_IOVA = 1 << 0, +}; +int iopt_map_user_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, + unsigned long *iova, void __user *uptr, + unsigned long length, int iommu_prot, + unsigned int flags); +int iopt_map_pages(struct io_pagetable *iopt, struct list_head *pages_list, + unsigned long length, unsigned long *dst_iova, + int iommu_prot, unsigned int flags); +int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova, + unsigned long length, unsigned long *unmapped); +int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped); + +int iopt_table_add_domain(struct io_pagetable *iopt, + struct iommu_domain *domain); +void iopt_table_remove_domain(struct io_pagetable *iopt, + struct iommu_domain *domain); +int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt, + struct device *device, + struct iommu_group *group, + phys_addr_t *sw_msi_start); +int iopt_set_allow_iova(struct io_pagetable *iopt, + struct rb_root_cached *allowed_iova); +int iopt_reserve_iova(struct io_pagetable *iopt, unsigned long start, + unsigned long last, void *owner); +void iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner); +int iopt_cut_iova(struct io_pagetable *iopt, unsigned long *iovas, + size_t num_iovas); +void iopt_enable_large_pages(struct io_pagetable *iopt); +int iopt_disable_large_pages(struct io_pagetable *iopt); + struct iommufd_ucmd { struct iommufd_ctx *ictx; void __user *ubuffer;

The hw_pagetable object exposes the internal struct iommu_domain's to userspace. An iommu_domain is required when any DMA device attaches to an IOAS to control the io page table through the iommu driver.

For compatibility with VFIO the hw_pagetable is automatically created when a DMA device is attached to the IOAS. If a compatible iommu_domain already exists then the hw_pagetable associated with it is used for the attachment.

In the initial series there is no iommufd uAPI for the hw_pagetable object. The next patch provides driver facing APIs for IO page table attachment that allows drivers to accept either an IOAS or a hw_pagetable ID and for the driver to return the hw_pagetable ID that was auto-selected from an IOAS. The expectation is the driver will provide uAPI through its own FD for attaching its device to iommufd. This allows userspace to learn the mapping of devices to iommu_domains and to override the automatic attachment.

The future HW specific interface will allow userspace to create hw_pagetable objects using iommu_domains with IOMMU driver specific parameters. This infrastructure will allow linking those domains to IOAS's and devices.

Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/Makefile | 1 + drivers/iommu/iommufd/hw_pagetable.c | 57 +++++++++++++++++++++++++ drivers/iommu/iommufd/ioas.c | 4 ++ drivers/iommu/iommufd/iommufd_private.h | 34 +++++++++++++++ drivers/iommu/iommufd/main.c | 3 ++ 5 files changed, 99 insertions(+) create mode 100644 drivers/iommu/iommufd/hw_pagetable.c

diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile index 2b4f36f1b72f9d..e13e971aa28c60 100644 --- a/drivers/iommu/iommufd/Makefile +++ b/drivers/iommu/iommufd/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only iommufd-y := \ + hw_pagetable.o \ io_pagetable.o \ ioas.o \ main.o \ diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c new file mode 100644 index 00000000000000..43d473989a0667 --- /dev/null +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES + */ +#include <linux/iommu.h> + +#include "iommufd_private.h" + +void iommufd_hw_pagetable_destroy(struct iommufd_object *obj) +{ + struct iommufd_hw_pagetable *hwpt = + container_of(obj, struct iommufd_hw_pagetable, obj); + + WARN_ON(!list_empty(&hwpt->devices)); + + iommu_domain_free(hwpt->domain); + refcount_dec(&hwpt->ioas->obj.users); + mutex_destroy(&hwpt->devices_lock); +} + +/** + * iommufd_hw_pagetable_alloc() - Get an iommu_domain for a device + * @ictx: iommufd context + * @ioas: IOAS to associate the domain with + * @dev: Device to get an iommu_domain for + * + * Allocate a new iommu_domain and return it as a hw_pagetable. + */ +struct iommufd_hw_pagetable * +iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, + struct device *dev) +{ + struct iommufd_hw_pagetable *hwpt; + int rc; + + hwpt = iommufd_object_alloc(ictx, hwpt, IOMMUFD_OBJ_HW_PAGETABLE); + if (IS_ERR(hwpt)) + return hwpt; + + hwpt->domain = iommu_domain_alloc(dev->bus); + if (!hwpt->domain) { + rc = -ENOMEM; + goto out_abort; + } + + INIT_LIST_HEAD(&hwpt->devices); + INIT_LIST_HEAD(&hwpt->hwpt_item); + mutex_init(&hwpt->devices_lock); + /* Pairs with iommufd_hw_pagetable_destroy() */ + refcount_inc(&ioas->obj.users); + hwpt->ioas = ioas; + return hwpt; + +out_abort: + iommufd_object_abort(ictx, &hwpt->obj); + return ERR_PTR(rc); +} diff --git a/drivers/iommu/iommufd/ioas.c b/drivers/iommu/iommufd/ioas.c index 6963b7b0a3c957..52ca5776e00b8f 100644 --- a/drivers/iommu/iommufd/ioas.c +++ b/drivers/iommu/iommufd/ioas.c @@ -17,6 +17,7 @@ void iommufd_ioas_destroy(struct iommufd_object *obj) rc = iopt_unmap_all(&ioas->iopt, NULL); WARN_ON(rc && rc != -ENOENT); iopt_destroy_table(&ioas->iopt); + mutex_destroy(&ioas->mutex); }

struct iommufd_ioas *iommufd_ioas_alloc(struct iommufd_ctx *ictx) @@ -31,6 +32,9 @@ struct iommufd_ioas *iommufd_ioas_alloc(struct iommufd_ctx *ictx) rc = iopt_init_table(&ioas->iopt); if (rc) goto out_abort; + + INIT_LIST_HEAD(&ioas->hwpt_list); + mutex_init(&ioas->mutex); return ioas;

out_abort: diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 20e1e3801fc525..e1521764a335e6 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -102,6 +102,7 @@ static inline int iommufd_ucmd_respond(struct iommufd_ucmd *ucmd, enum iommufd_object_type { IOMMUFD_OBJ_NONE, IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE, + IOMMUFD_OBJ_HW_PAGETABLE, IOMMUFD_OBJ_IOAS, };

@@ -179,10 +180,20 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, * io_pagetable object. It is a user controlled mapping of IOVA -> PFNs. The * mapping is copied into all of the associated domains and made available to * in-kernel users. + * + * Every iommu_domain that is created is wrapped in a iommufd_hw_pagetable + * object. When we go to attach a device to an IOAS we need to get an + * iommu_domain and wrapping iommufd_hw_pagetable for it. + * + * An iommu_domain & iommfd_hw_pagetable will be automatically selected + * for a device based on the hwpt_list. If no suitable iommu_domain + * is found a new iommu_domain will be created. */ struct iommufd_ioas { struct iommufd_object obj; struct io_pagetable iopt; + struct mutex mutex; + struct list_head hwpt_list; };

static inline struct iommufd_ioas *iommufd_get_ioas(struct iommufd_ucmd *ucmd, @@ -204,4 +215,27 @@ int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd); int iommufd_ioas_option(struct iommufd_ucmd *ucmd); int iommufd_option_rlimit_mode(struct iommu_option *cmd, struct iommufd_ctx *ictx); + +/* + * A HW pagetable is called an iommu_domain inside the kernel. This user object + * allows directly creating and inspecting the domains. Domains that have kernel + * owned page tables will be associated with an iommufd_ioas that provides the + * IOVA to PFN map. + */ +struct iommufd_hw_pagetable { + struct iommufd_object obj; + struct iommufd_ioas *ioas; + struct iommu_domain *domain; + bool auto_domain : 1; + /* Head at iommufd_ioas::hwpt_list */ + struct list_head hwpt_item; + struct mutex devices_lock; + struct list_head devices; +}; + +struct iommufd_hw_pagetable * +iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, + struct device *dev); +void iommufd_hw_pagetable_destroy(struct iommufd_object *obj); + #endif diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index c91156ba3e3ab3..84d315b9e73845 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -355,6 +355,9 @@ static struct iommufd_object_ops iommufd_object_ops[] = { [IOMMUFD_OBJ_IOAS] = { .destroy = iommufd_ioas_destroy, }, + [IOMMUFD_OBJ_HW_PAGETABLE] = { + .destroy = iommufd_hw_pagetable_destroy, + }, };

static struct miscdevice iommu_misc_dev = {

Add the four functions external drivers need to connect physical DMA to the IOMMUFD:

iommufd_device_bind() / iommufd_device_unbind() Register the device with iommufd and establish security isolation.

iommufd_device_attach() / iommufd_device_detach() Connect a bound device to a page table

Binding a device creates a device object ID in the uAPI, however the generic API provides no IOCTLs to manipulate them.

Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/Makefile | 1 + drivers/iommu/iommufd/device.c | 399 ++++++++++++++++++++++++ drivers/iommu/iommufd/iommufd_private.h | 5 + drivers/iommu/iommufd/main.c | 3 + include/linux/iommufd.h | 13 + 5 files changed, 421 insertions(+) create mode 100644 drivers/iommu/iommufd/device.c

diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile index e13e971aa28c60..ca28a135b9675f 100644 --- a/drivers/iommu/iommufd/Makefile +++ b/drivers/iommu/iommufd/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only iommufd-y := \ + device.o \ hw_pagetable.o \ io_pagetable.o \ ioas.o \ diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c new file mode 100644 index 00000000000000..b572b01f67b7b5 --- /dev/null +++ b/drivers/iommu/iommufd/device.c @@ -0,0 +1,399 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES + */ +#include <linux/iommufd.h> +#include <linux/slab.h> +#include <linux/iommu.h> +#include <linux/irqdomain.h> + +#include "iommufd_private.h" + +/* + * A iommufd_device object represents the binding relationship between a + * consuming driver and the iommufd. These objects are created/destroyed by + * external drivers, not by userspace. + */ +struct iommufd_device { + struct iommufd_object obj; + struct iommufd_ctx *ictx; + struct iommufd_hw_pagetable *hwpt; + /* Head at iommufd_hw_pagetable::devices */ + struct list_head devices_item; + /* always the physical device */ + struct device *dev; + struct iommu_group *group; + bool enforce_cache_coherency; +}; + +void iommufd_device_destroy(struct iommufd_object *obj) +{ + struct iommufd_device *idev = + container_of(obj, struct iommufd_device, obj); + + iommu_device_release_dma_owner(idev->dev); + iommu_group_put(idev->group); + iommufd_ctx_put(idev->ictx); +} + +/** + * iommufd_device_bind - Bind a physical device to an iommu fd + * @ictx: iommufd file descriptor + * @dev: Pointer to a physical PCI device struct + * @id: Output ID number to return to userspace for this device + * + * A successful bind establishes an ownership over the device and returns + * struct iommufd_device pointer, otherwise returns error pointer. + * + * A driver using this API must set driver_managed_dma and must not touch + * the device until this routine succeeds and establishes ownership. + * + * Binding a PCI device places the entire RID under iommufd control. + * + * The caller must undo this with iommufd_unbind_device() + */ +struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, + struct device *dev, u32 *id) +{ + struct iommufd_device *idev; + struct iommu_group *group; + int rc; + + /* + * iommufd always sets IOMMU_CACHE because we offer no way for userspace + * to restore cache coherency. + */ + if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY)) + return ERR_PTR(-EINVAL); + + group = iommu_group_get(dev); + if (!group) + return ERR_PTR(-ENODEV); + + rc = iommu_device_claim_dma_owner(dev, ictx); + if (rc) + goto out_group_put; + + idev = iommufd_object_alloc(ictx, idev, IOMMUFD_OBJ_DEVICE); + if (IS_ERR(idev)) { + rc = PTR_ERR(idev); + goto out_release_owner; + } + idev->ictx = ictx; + iommufd_ctx_get(ictx); + idev->dev = dev; + idev->enforce_cache_coherency = + device_iommu_capable(dev, IOMMU_CAP_ENFORCE_CACHE_COHERENCY); + /* The calling driver is a user until iommufd_device_unbind() */ + refcount_inc(&idev->obj.users); + /* group refcount moves into iommufd_device */ + idev->group = group; + + /* + * If the caller fails after this success it must call + * iommufd_unbind_device() which is safe since we hold this refcount. + * This also means the device is a leaf in the graph and no other object + * can take a reference on it. + */ + iommufd_object_finalize(ictx, &idev->obj); + *id = idev->obj.id; + return idev; + +out_release_owner: + iommu_device_release_dma_owner(dev); +out_group_put: + iommu_group_put(group); + return ERR_PTR(rc); +} +EXPORT_SYMBOL_NS_GPL(iommufd_device_bind, IOMMUFD); + +void iommufd_device_unbind(struct iommufd_device *idev) +{ + bool was_destroyed; + + was_destroyed = iommufd_object_destroy_user(idev->ictx, &idev->obj); + WARN_ON(!was_destroyed); +} +EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD); + +static int iommufd_device_setup_msi(struct iommufd_device *idev, + struct iommufd_hw_pagetable *hwpt, + phys_addr_t sw_msi_start, + unsigned int flags) +{ + int rc; + + /* + * IOMMU_CAP_INTR_REMAP means that the platform is isolating MSI, and it + * creates the MSI window by default in the iommu domain. Nothing + * further to do. + */ + if (device_iommu_capable(idev->dev, IOMMU_CAP_INTR_REMAP)) + return 0; + + /* + * On ARM systems that set the global IRQ_DOMAIN_FLAG_MSI_REMAP every + * allocated iommu_domain will block interrupts by default and this + * special flow is needed to turn them back on. iommu_dma_prepare_msi() + * will install pages into our domain after request_irq() to make this + * work. + * + * FIXME: This is conceptually broken for iommufd since we want to allow + * userspace to change the domains, eg switch from an identity IOAS to a + * DMA IOAs. There is currently no way to create a MSI window that + * matches what the IRQ layer actually expects in a newly created + * domain. + */ + if (irq_domain_check_msi_remap()) { + if (WARN_ON(!sw_msi_start)) + return -EPERM; + /* + * iommu_get_msi_cookie() can only be called once per domain, + * it returns -EBUSY on later calls. + */ + if (hwpt->msi_cookie) + return 0; + rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start); + if (rc && rc != -ENODEV) + return rc; + hwpt->msi_cookie = true; + return 0; + } + + /* + * Otherwise the platform has a MSI window that is not isolated. For + * historical compat with VFIO allow a module parameter to ignore the + * insecurity. + */ + if (!(flags & IOMMUFD_ATTACH_FLAGS_ALLOW_UNSAFE_INTERRUPT)) + return -EPERM; + return 0; +} + +static bool iommufd_hw_pagetable_has_group(struct iommufd_hw_pagetable *hwpt, + struct iommu_group *group) +{ + struct iommufd_device *cur_dev; + + list_for_each_entry(cur_dev, &hwpt->devices, devices_item) + if (cur_dev->group == group) + return true; + return false; +} + +static int iommufd_device_do_attach(struct iommufd_device *idev, + struct iommufd_hw_pagetable *hwpt, + unsigned int flags) +{ + phys_addr_t sw_msi_start = 0; + int rc; + + mutex_lock(&hwpt->devices_lock); + + /* + * Try to upgrade the domain we have, it is an iommu driver bug to + * report IOMMU_CAP_ENFORCE_CACHE_COHERENCY but fail + * enforce_cache_coherency when there are no devices attached to the + * domain. + */ + if (idev->enforce_cache_coherency && !hwpt->enforce_cache_coherency) { + if (hwpt->domain->ops->enforce_cache_coherency) + hwpt->enforce_cache_coherency = + hwpt->domain->ops->enforce_cache_coherency( + hwpt->domain); + if (!hwpt->enforce_cache_coherency) { + WARN_ON(list_empty(&hwpt->devices)); + rc = -EINVAL; + goto out_unlock; + } + } + + rc = iopt_table_enforce_group_resv_regions(&hwpt->ioas->iopt, idev->dev, + idev->group, &sw_msi_start); + if (rc) + goto out_iova; + + rc = iommufd_device_setup_msi(idev, hwpt, sw_msi_start, flags); + if (rc) + goto out_iova; + + /* + * FIXME: Hack around missing a device-centric iommu api, only attach to + * the group once for the first device that is in the group. + */ + if (!iommufd_hw_pagetable_has_group(hwpt, idev->group)) { + rc = iommu_attach_group(hwpt->domain, idev->group); + if (rc) + goto out_iova; + } + + if (list_empty(&hwpt->devices)) { + rc = iopt_table_add_domain(&hwpt->ioas->iopt, hwpt->domain); + if (rc) + goto out_detach; + } + + idev->hwpt = hwpt; + refcount_inc(&hwpt->obj.users); + list_add(&idev->devices_item, &hwpt->devices); + mutex_unlock(&hwpt->devices_lock); + return 0; + +out_detach: + iommu_detach_group(hwpt->domain, idev->group); +out_iova: + iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev); +out_unlock: + mutex_unlock(&hwpt->devices_lock); + return rc; +} + +/* + * When automatically managing the domains we search for a compatible domain in + * the iopt and if one is found use it, otherwise create a new domain. + * Automatic domain selection will never pick a manually created domain. + */ +static int iommufd_device_auto_get_domain(struct iommufd_device *idev, + struct iommufd_ioas *ioas, + unsigned int flags) +{ + struct iommufd_hw_pagetable *hwpt; + int rc; + + /* + * There is no differentiation when domains are allocated, so any domain + * that is willing to attach to the device is interchangeable with any + * other. + */ + mutex_lock(&ioas->mutex); + list_for_each_entry(hwpt, &ioas->hwpt_list, hwpt_item) { + if (!hwpt->auto_domain || + !refcount_inc_not_zero(&hwpt->obj.users)) + continue; + + rc = iommufd_device_do_attach(idev, hwpt, flags); + refcount_dec(&hwpt->obj.users); + if (rc) { + /* + * FIXME: Requires the series to return EINVAL for + * incompatible domain attaches. + */ + if (rc == -EINVAL) + continue; + goto out_unlock; + } + goto out_unlock; + } + + hwpt = iommufd_hw_pagetable_alloc(idev->ictx, ioas, idev->dev); + if (IS_ERR(hwpt)) { + rc = PTR_ERR(hwpt); + goto out_unlock; + } + hwpt->auto_domain = true; + + rc = iommufd_device_do_attach(idev, hwpt, flags); + if (rc) + goto out_abort; + list_add_tail(&hwpt->hwpt_item, &ioas->hwpt_list); + + mutex_unlock(&ioas->mutex); + iommufd_object_finalize(idev->ictx, &hwpt->obj); + return 0; + +out_abort: + iommufd_object_abort_and_destroy(idev->ictx, &hwpt->obj); +out_unlock: + mutex_unlock(&ioas->mutex); + return rc; +} + +/** + * iommufd_device_attach - Connect a device to an iommu_domain + * @idev: device to attach + * @pt_id: Input a IOMMUFD_OBJ_IOAS, or IOMMUFD_OBJ_HW_PAGETABLE + * Output the IOMMUFD_OBJ_HW_PAGETABLE ID + * @flags: Optional flags + * + * This connects the device to an iommu_domain, either automatically or manually + * selected. Once this completes the device could do DMA. + * + * The caller should return the resulting pt_id back to userspace. + * This function is undone by calling iommufd_device_detach(). + */ +int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id, + unsigned int flags) +{ + struct iommufd_object *pt_obj; + int rc; + + pt_obj = iommufd_get_object(idev->ictx, *pt_id, IOMMUFD_OBJ_ANY); + if (IS_ERR(pt_obj)) + return PTR_ERR(pt_obj); + + switch (pt_obj->type) { + case IOMMUFD_OBJ_HW_PAGETABLE: { + struct iommufd_hw_pagetable *hwpt = + container_of(pt_obj, struct iommufd_hw_pagetable, obj); + + rc = iommufd_device_do_attach(idev, hwpt, flags); + if (rc) + goto out_put_pt_obj; + + mutex_lock(&hwpt->ioas->mutex); + list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list); + mutex_unlock(&hwpt->ioas->mutex); + break; + } + case IOMMUFD_OBJ_IOAS: { + struct iommufd_ioas *ioas = + container_of(pt_obj, struct iommufd_ioas, obj); + + rc = iommufd_device_auto_get_domain(idev, ioas, flags); + if (rc) + goto out_put_pt_obj; + break; + } + default: + rc = -EINVAL; + goto out_put_pt_obj; + } + + refcount_inc(&idev->obj.users); + *pt_id = idev->hwpt->obj.id; + rc = 0; + +out_put_pt_obj: + iommufd_put_object(pt_obj); + return rc; +} +EXPORT_SYMBOL_NS_GPL(iommufd_device_attach, IOMMUFD); + +void iommufd_device_detach(struct iommufd_device *idev) +{ + struct iommufd_hw_pagetable *hwpt = idev->hwpt; + + mutex_lock(&hwpt->ioas->mutex); + mutex_lock(&hwpt->devices_lock); + list_del(&idev->devices_item); + if (!iommufd_hw_pagetable_has_group(hwpt, idev->group)) { + if (list_empty(&hwpt->devices)) { + iopt_table_remove_domain(&hwpt->ioas->iopt, + hwpt->domain); + list_del(&hwpt->hwpt_item); + } + iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev); + iommu_detach_group(hwpt->domain, idev->group); + } + mutex_unlock(&hwpt->devices_lock); + mutex_unlock(&hwpt->ioas->mutex); + + if (hwpt->auto_domain) + iommufd_object_destroy_user(idev->ictx, &hwpt->obj); + else + refcount_dec(&hwpt->obj.users); + + idev->hwpt = NULL; + + refcount_dec(&idev->obj.users); +} +EXPORT_SYMBOL_NS_GPL(iommufd_device_detach, IOMMUFD); diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index e1521764a335e6..e982efca161699 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -102,6 +102,7 @@ static inline int iommufd_ucmd_respond(struct iommufd_ucmd *ucmd, enum iommufd_object_type { IOMMUFD_OBJ_NONE, IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE, + IOMMUFD_OBJ_DEVICE, IOMMUFD_OBJ_HW_PAGETABLE, IOMMUFD_OBJ_IOAS, }; @@ -227,6 +228,8 @@ struct iommufd_hw_pagetable { struct iommufd_ioas *ioas; struct iommu_domain *domain; bool auto_domain : 1; + bool enforce_cache_coherency : 1; + bool msi_cookie : 1; /* Head at iommufd_ioas::hwpt_list */ struct list_head hwpt_item; struct mutex devices_lock; @@ -238,4 +241,6 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, struct device *dev); void iommufd_hw_pagetable_destroy(struct iommufd_object *obj);

+void iommufd_device_destroy(struct iommufd_object *obj); + #endif diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 84d315b9e73845..774c286da04d38 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -352,6 +352,9 @@ void iommufd_ctx_put(struct iommufd_ctx *ictx) EXPORT_SYMBOL_NS_GPL(iommufd_ctx_put, IOMMUFD);

static struct iommufd_object_ops iommufd_object_ops[] = { + [IOMMUFD_OBJ_DEVICE] = { + .destroy = iommufd_device_destroy, + }, [IOMMUFD_OBJ_IOAS] = { .destroy = iommufd_ioas_destroy, }, diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h index 26e09d539737bb..31efacd8a46cce 100644 --- a/include/linux/iommufd.h +++ b/include/linux/iommufd.h @@ -9,10 +9,23 @@ #include <linux/types.h> #include <linux/errno.h> #include <linux/err.h> +#include <linux/device.h>

+struct iommufd_device; struct iommufd_ctx; struct file;

+struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, + struct device *dev, u32 *id); +void iommufd_device_unbind(struct iommufd_device *idev); + +enum { + IOMMUFD_ATTACH_FLAGS_ALLOW_UNSAFE_INTERRUPT = 1 << 0, +}; +int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id, + unsigned int flags); +void iommufd_device_detach(struct iommufd_device *idev); + enum { IOMMUFD_ACCESS_RW_READ = 0, IOMMUFD_ACCESS_RW_WRITE = 1 << 0,

Kernel access is the mode that VFIO "mdevs" use. In this case there is no struct device and no IOMMU connection. iommufd acts as a record keeper for accesses and returns the actual struct pages back to the caller to use however they need. eg with kmap or the DMA API.

Each caller must create a struct iommufd_access with iommufd_access_create(), similar to how iommufd_device_bind() works. Using this struct the caller can access blocks of IOVA using iommufd_access_pin_pages() or iommufd_access_rw().

Callers must provide a callback that immediately unpins any IOVA being used within a range. This happens if userspace unmaps the IOVA under the pin.

The implementation forwards the access requests directly to the iopt infrastructure that manages the iopt_pages_access.

Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/device.c | 307 ++++++++++++++++++++++++ drivers/iommu/iommufd/io_pagetable.c | 7 +- drivers/iommu/iommufd/ioas.c | 2 + drivers/iommu/iommufd/iommufd_private.h | 6 + drivers/iommu/iommufd/main.c | 3 + include/linux/iommufd.h | 42 +++- 6 files changed, 364 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index b572b01f67b7b5..b4a799b2b41ae3 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -6,6 +6,7 @@ #include <linux/iommu.h> #include <linux/irqdomain.h>

+#include "io_pagetable.h" #include "iommufd_private.h"

/* @@ -25,6 +26,15 @@ struct iommufd_device { bool enforce_cache_coherency; };

+struct iommufd_access { + struct iommufd_object obj; + struct iommufd_ctx *ictx; + struct iommufd_ioas *ioas; + const struct iommufd_access_ops *ops; + void *data; + u32 ioas_access_list_id; +}; + void iommufd_device_destroy(struct iommufd_object *obj) { struct iommufd_device *idev = @@ -397,3 +407,300 @@ void iommufd_device_detach(struct iommufd_device *idev) refcount_dec(&idev->obj.users); } EXPORT_SYMBOL_NS_GPL(iommufd_device_detach, IOMMUFD); + +void iommufd_access_destroy_object(struct iommufd_object *obj) +{ + struct iommufd_access *access = + container_of(obj, struct iommufd_access, obj); + + WARN_ON(xa_erase(&access->ioas->access_list, + access->ioas_access_list_id) != access); + iommufd_ctx_put(access->ictx); + refcount_dec(&access->ioas->obj.users); +} + +struct iommufd_access * +iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id, + const struct iommufd_access_ops *ops, void *data) +{ + struct iommufd_access *access; + struct iommufd_object *obj; + int rc; + + /* + * There is no uAPI for the access object, but to keep things symmetric + * use the object infrastructure anyhow. + */ + access = iommufd_object_alloc(ictx, access, IOMMUFD_OBJ_ACCESS); + if (IS_ERR(access)) + return access; + + obj = iommufd_get_object(ictx, ioas_id, IOMMUFD_OBJ_IOAS); + if (IS_ERR(obj)) { + rc = PTR_ERR(obj); + goto out_abort; + } + access->ioas = container_of(obj, struct iommufd_ioas, obj); + iommufd_put_object_keep_user(obj); + + rc = xa_alloc(&access->ioas->access_list, &access->ioas_access_list_id, + access, xa_limit_16b, GFP_KERNEL_ACCOUNT); + if (rc) + goto out_put_ioas; + + /* The calling driver is a user until iommufd_access_destroy() */ + refcount_inc(&access->obj.users); + access->ictx = ictx; + access->data = data; + iommufd_ctx_get(ictx); + iommufd_object_finalize(ictx, &access->obj); + return access; +out_put_ioas: + refcount_dec(&access->ioas->obj.users); +out_abort: + iommufd_object_abort(ictx, &access->obj); + return ERR_PTR(rc); +} +EXPORT_SYMBOL_NS_GPL(iommufd_access_create, IOMMUFD); + +void iommufd_access_destroy(struct iommufd_access *access) +{ + bool was_destroyed; + + was_destroyed = iommufd_object_destroy_user(access->ictx, &access->obj); + WARN_ON(!was_destroyed); +} +EXPORT_SYMBOL_NS_GPL(iommufd_access_destroy, IOMMUFD); + +/** + * iommufd_access_notify_unmap - Notify users of an iopt to stop using it + * @iopt - iopt to work on + * @iova - Starting iova in the iopt + * @length - Number of bytes + * + * After this function returns there should be no users attached to the pages + * linked to this iopt that intersect with iova,length. Anyone that has attached + * a user through iopt_access_pages() needs to detatch it through + * iommufd_access_unpin_pages() before this function returns. + * + * The unmap callback may not call or wait for a iommufd_access_destroy() to + * complete. Once iommufd_access_destroy() returns no ops are running and no + * future ops will be called. + */ +void iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long iova, + unsigned long length) +{ + struct iommufd_ioas *ioas = + container_of(iopt, struct iommufd_ioas, iopt); + struct iommufd_access *access; + unsigned long index; + + xa_lock(&ioas->access_list); + xa_for_each(&ioas->access_list, index, access) { + if (!iommufd_lock_obj(&access->obj)) + continue; + xa_unlock(&ioas->access_list); + + access->ops->unmap(access->data, iova, length); + + iommufd_put_object(&access->obj); + xa_lock(&ioas->access_list); + } + xa_unlock(&ioas->access_list); +} + +/** + * iommufd_access_unpin_pages() - Undo iommufd_access_pin_pages + * @access: IOAS access to act on + * @iova: Starting IOVA + * @length:- Number of bytes to access + * + * Return the struct page's. The caller must stop accessing them before calling + * this. The iova/length must exactly match the one provided to access_pages. + */ +void iommufd_access_unpin_pages(struct iommufd_access *access, + unsigned long iova, unsigned long length) +{ + struct io_pagetable *iopt = &access->ioas->iopt; + struct iopt_area_contig_iter iter; + unsigned long last_iova; + struct iopt_area *area; + + if (WARN_ON(!length) || + WARN_ON(check_add_overflow(iova, length - 1, &last_iova))) + return; + + down_read(&iopt->iova_rwsem); + iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) + iopt_pages_remove_access( + area, iopt_area_iova_to_index(area, iter.cur_iova), + iopt_area_iova_to_index( + area, + min(last_iova, iopt_area_last_iova(area)))); + up_read(&iopt->iova_rwsem); + WARN_ON(!iopt_area_contig_done(&iter)); +} +EXPORT_SYMBOL_NS_GPL(iommufd_access_unpin_pages, IOMMUFD); + +static bool iopt_area_contig_is_aligned(struct iopt_area_contig_iter *iter, + bool first) +{ + if (iopt_area_start_byte(iter->area, iter->cur_iova) % PAGE_SIZE) + return false; + + if (!iopt_area_contig_done(iter) && + (iopt_area_start_byte(iter->area, iopt_area_last_iova(iter->area)) % + PAGE_SIZE) != (PAGE_SIZE - 1)) + return false; + return true; +} + +static bool check_area_prot(struct iopt_area *area, unsigned int flags) +{ + if (flags & IOMMUFD_ACCESS_RW_WRITE) + return area->iommu_prot & IOMMU_WRITE; + return area->iommu_prot & IOMMU_READ; +} + +/** + * iommufd_access_pin_pages() - Return a list of pages under the iova + * @access: IOAS access to act on + * @iova: Starting IOVA + * @length: Number of bytes to access + * @out_pages: Output page list + * @flags: IOPMMUFD_ACCESS_RW_* flags + * + * Reads @length bytes starting at iova and returns the struct page * pointers. + * These can be kmap'd by the caller for CPU access. + * + * The caller must perform iopt_unaccess_pages() when done to balance this. + * + * This API always requires a page aligned iova. This happens naturally if the + * ioas alignment is >= PAGE_SIZE and the iova is PAGE_SIZE aligned. However + * smaller alignments have corner cases where this API can fail on otherwise + * aligned iova. + */ +int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, + unsigned long length, struct page **out_pages, + unsigned int flags) +{ + struct io_pagetable *iopt = &access->ioas->iopt; + struct iopt_area_contig_iter iter; + unsigned long last_iova; + struct iopt_area *area; + bool first = true; + int rc; + + if (!length) + return -EINVAL; + if (check_add_overflow(iova, length - 1, &last_iova)) + return -EOVERFLOW; + + down_read(&iopt->iova_rwsem); + iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) { + unsigned long last = min(last_iova, iopt_area_last_iova(area)); + unsigned long last_index = iopt_area_iova_to_index(area, last); + unsigned long index = + iopt_area_iova_to_index(area, iter.cur_iova); + + if (area->prevent_access || + !iopt_area_contig_is_aligned(&iter, first)) { + rc = -EINVAL; + goto err_remove; + } + + if (!check_area_prot(area, flags)) { + rc = -EPERM; + goto err_remove; + } + first = false; + + mutex_lock(&area->pages->mutex); + rc = iopt_pages_add_access(area->pages, index, last_index, + out_pages, flags); + if (rc) { + mutex_unlock(&area->pages->mutex); + goto err_remove; + } + area->num_accesses++; + mutex_unlock(&area->pages->mutex); + out_pages += last_index - index + 1; + } + if (!iopt_area_contig_done(&iter)) { + rc = -ENOENT; + goto err_remove; + } + + up_read(&iopt->iova_rwsem); + return 0; + +err_remove: + if (iova < iter.cur_iova) { + last_iova = iter.cur_iova - 1; + iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) + iopt_pages_remove_access( + area, + iopt_area_iova_to_index(area, iter.cur_iova), + iopt_area_iova_to_index( + area, min(last_iova, + iopt_area_last_iova(area)))); + } + up_read(&iopt->iova_rwsem); + return rc; +} +EXPORT_SYMBOL_NS_GPL(iommufd_access_pin_pages, IOMMUFD); + +/** + * iommufd_access_rw - Read or write data under the iova + * @access: IOAS access to act on + * @iova: Starting IOVA + * @data: Kernel buffer to copy to/from + * @length: Number of bytes to access + * + * Copy kernel to/from data into the range given by IOVA/length. If flags + * indicates IOMMUFD_ACCESS_RW_KTHREAD then a large copy can be optimized + * by changing it into copy_to/from_user(). + */ +int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, + void *data, size_t length, unsigned int flags) +{ + struct io_pagetable *iopt = &access->ioas->iopt; + struct iopt_area_contig_iter iter; + struct iopt_area *area; + unsigned long last_iova; + int rc; + + if (!length) + return -EINVAL; + if (check_add_overflow(iova, length - 1, &last_iova)) + return -EOVERFLOW; + + down_read(&iopt->iova_rwsem); + iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) { + unsigned long last = min(last_iova, iopt_area_last_iova(area)); + unsigned long bytes = (last - iter.cur_iova) + 1; + + if (area->prevent_access) { + rc = -EINVAL; + goto err_out; + } + + if (!check_area_prot(area, flags)) { + rc = -EPERM; + goto err_out; + } + + rc = iopt_pages_rw_access( + area->pages, iopt_area_start_byte(area, iter.cur_iova), + data, bytes, flags); + if (rc) + goto err_out; + data += bytes; + } + if (!iopt_area_contig_done(&iter)) + rc = -ENOENT; +err_out: + up_read(&iopt->iova_rwsem); + return rc; +} +EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, IOMMUFD); diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index 27cbb652ee33cd..bc24227100fe22 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -463,6 +463,7 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start, * is NULL. This prevents domain attach/detatch from running * concurrently with cleaning up the area. */ +again: down_read(&iopt->domains_rwsem); down_write(&iopt->iova_rwsem); while ((area = iopt_area_iter_first(iopt, start, end))) { @@ -491,8 +492,10 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start, area->prevent_access = true; up_write(&iopt->iova_rwsem); up_read(&iopt->domains_rwsem); - /* Later patch calls back to drivers to unmap */ - return -EBUSY; + iommufd_access_notify_unmap(iopt, area_first, + iopt_area_length(area)); + WARN_ON(READ_ONCE(area->num_accesses)); + goto again; }

pages = area->pages; diff --git a/drivers/iommu/iommufd/ioas.c b/drivers/iommu/iommufd/ioas.c index 52ca5776e00b8f..078478a9a7b92f 100644 --- a/drivers/iommu/iommufd/ioas.c +++ b/drivers/iommu/iommufd/ioas.c @@ -17,6 +17,7 @@ void iommufd_ioas_destroy(struct iommufd_object *obj) rc = iopt_unmap_all(&ioas->iopt, NULL); WARN_ON(rc && rc != -ENOENT); iopt_destroy_table(&ioas->iopt); + WARN_ON(!xa_empty(&ioas->access_list)); mutex_destroy(&ioas->mutex); }

@@ -35,6 +36,7 @@ struct iommufd_ioas *iommufd_ioas_alloc(struct iommufd_ctx *ictx)

INIT_LIST_HEAD(&ioas->hwpt_list); mutex_init(&ioas->mutex); + xa_init_flags(&ioas->access_list, XA_FLAGS_ALLOC); return ioas;

out_abort: diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index e982efca161699..5be8983b8524e2 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -64,6 +64,8 @@ int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova, unsigned long length, unsigned long *unmapped); int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped);

+void iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long iova, + unsigned long length); int iopt_table_add_domain(struct io_pagetable *iopt, struct iommu_domain *domain); void iopt_table_remove_domain(struct io_pagetable *iopt, @@ -105,6 +107,7 @@ enum iommufd_object_type { IOMMUFD_OBJ_DEVICE, IOMMUFD_OBJ_HW_PAGETABLE, IOMMUFD_OBJ_IOAS, + IOMMUFD_OBJ_ACCESS, };

/* Base struct for all objects with a userspace ID handle. */ @@ -195,6 +198,7 @@ struct iommufd_ioas { struct io_pagetable iopt; struct mutex mutex; struct list_head hwpt_list; + struct xarray access_list; };

static inline struct iommufd_ioas *iommufd_get_ioas(struct iommufd_ucmd *ucmd, @@ -243,4 +247,6 @@ void iommufd_hw_pagetable_destroy(struct iommufd_object *obj);

void iommufd_device_destroy(struct iommufd_object *obj);

+void iommufd_access_destroy_object(struct iommufd_object *obj); + #endif diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 774c286da04d38..15ffda848741c9 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -352,6 +352,9 @@ void iommufd_ctx_put(struct iommufd_ctx *ictx) EXPORT_SYMBOL_NS_GPL(iommufd_ctx_put, IOMMUFD);

static struct iommufd_object_ops iommufd_object_ops[] = { + [IOMMUFD_OBJ_ACCESS] = { + .destroy = iommufd_access_destroy_object, + }, [IOMMUFD_OBJ_DEVICE] = { .destroy = iommufd_device_destroy, }, diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h index 31efacd8a46cce..0750df5a7def3e 100644 --- a/include/linux/iommufd.h +++ b/include/linux/iommufd.h @@ -9,10 +9,12 @@ #include <linux/types.h> #include <linux/errno.h> #include <linux/err.h> -#include <linux/device.h>

+struct device; struct iommufd_device; +struct page; struct iommufd_ctx; +struct iommufd_access; struct file;

struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, @@ -26,6 +28,10 @@ int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id, unsigned int flags); void iommufd_device_detach(struct iommufd_device *idev);

+struct iommufd_access_ops { + void (*unmap)(void *data, unsigned long iova, unsigned long length); +}; + enum { IOMMUFD_ACCESS_RW_READ = 0, IOMMUFD_ACCESS_RW_WRITE = 1 << 0, @@ -33,11 +39,24 @@ enum { IOMMUFD_ACCESS_RW_KTHREAD = 1 << 1, };

+struct iommufd_access * +iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id, + const struct iommufd_access_ops *ops, void *data); +void iommufd_access_destroy(struct iommufd_access *access); + void iommufd_ctx_get(struct iommufd_ctx *ictx);

#if IS_ENABLED(CONFIG_IOMMUFD) struct iommufd_ctx *iommufd_ctx_from_file(struct file *file); void iommufd_ctx_put(struct iommufd_ctx *ictx); + +int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, + unsigned long length, struct page **out_pages, + unsigned int flags); +void iommufd_access_unpin_pages(struct iommufd_access *access, + unsigned long iova, unsigned long length); +int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, + void *data, size_t len, unsigned int flags); #else /* !CONFIG_IOMMUFD */ static inline struct iommufd_ctx *iommufd_ctx_from_file(struct file *file) { @@ -47,5 +66,26 @@ static inline struct iommufd_ctx *iommufd_ctx_from_file(struct file *file) static inline void iommufd_ctx_put(struct iommufd_ctx *ictx) { } + +static inline int iommufd_access_pin_pages(struct iommufd_access *access, + unsigned long iova, + unsigned long length, + struct page **out_pages, + unsigned int flags) +{ + return -EOPNOTSUPP; +} + +static inline void iommufd_access_unpin_pages(struct iommufd_access *access, + unsigned long iova, + unsigned long length) +{ +} + +static inline int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, + void *data, size_t len, unsigned int flags) +{ + return -EOPNOTSUPP; +} #endif /* CONFIG_IOMMUFD */ #endif