This series is the start of adding full DMABUF support to iommufd. Currently it is limited to only work with VFIO's DMABUF exporter. It sits on top of Leon's series to add a DMABUF exporter to VFIO:
https://lore.kernel.org/all/cover.1760368250.git.leon@kernel.org/
The existing IOMMU_IOAS_MAP_FILE is enhanced to detect DMABUF fd's, but otherwise works the same as it does today for a memfd. The user can select a slice of the FD to map into the ioas and if the underliyng alignment requirements are met it will be placed in the iommu_domain.
Though limited, it is enough to allow a VMM like QEMU to connect MMIO BAR memory from VFIO to an iommu_domain controlled by iommufd. This is used for PCI Peer to Peer support in VMs, and is the last feature that the VFIO type 1 container has that iommufd couldn't do.
The VFIO type1 version extracts raw PFNs from VMAs, which has no lifetime control and is a use-after-free security problem.
Instead iommufd relies on revokable DMABUFs. Whenever VFIO thinks there should be no access to the MMIO it can shoot down the mapping in iommufd which will unmap it from the iommu_domain. There is no automatic remap, this is a safety protocol so the kernel doesn't get stuck. Userspace is expected to know it is doing something that will revoke the dmabuf and map/unmap it around the activity. Eg when QEMU goes to issue FLR it should do the map/unmap to iommufd.
Since DMABUF is missing some key general features for this use case it relies on a "private interconnect" between VFIO and iommufd via the vfio_pci_dma_buf_iommufd_map() call.
The call confirms the DMABUF has revoke semantics and delivers a phys_addr for the memory suitable for use with iommu_map().
Medium term there is a desire to expand the supported DMABUFs to include GPU drivers to support DPDK/SPDK type use cases so future series will work to add a general concept of revoke and a general negotiation of interconnect to remove vfio_pci_dma_buf_iommufd_map().
I also plan another series to modify iommufd's vfio_compat to transparently pull a dmabuf out of a VFIO VMA to emulate more of the uAPI of type1.
The latest series for interconnect negotation to exchange a phys_addr is: https://lore.kernel.org/r/20251027044712.1676175-1-vivek.kasireddy@intel.com
And the discussion for design of revoke is here: https://lore.kernel.org/dri-devel/20250114173103.GE5556@nvidia.com/
This is on github: https://github.com/jgunthorpe/linux/commits/iommufd_dmabuf
The branch has various modifications to Leon's series I've suggested.
Jason Gunthorpe (8): iommufd: Add DMABUF to iopt_pages iommufd: Do not map/unmap revoked DMABUFs iommufd: Allow a DMABUF to be revoked iommufd: Allow MMIO pages in a batch iommufd: Have pfn_reader process DMABUF iopt_pages iommufd: Have iopt_map_file_pages convert the fd to a file iommufd: Accept a DMABUF through IOMMU_IOAS_MAP_FILE iommufd/selftest: Add some tests for the dmabuf flow
drivers/iommu/iommufd/io_pagetable.c | 74 +++- drivers/iommu/iommufd/io_pagetable.h | 53 ++- drivers/iommu/iommufd/ioas.c | 8 +- drivers/iommu/iommufd/iommufd_private.h | 13 +- drivers/iommu/iommufd/iommufd_test.h | 10 + drivers/iommu/iommufd/main.c | 10 + drivers/iommu/iommufd/pages.c | 407 ++++++++++++++++-- drivers/iommu/iommufd/selftest.c | 142 ++++++ tools/testing/selftests/iommu/iommufd.c | 43 ++ tools/testing/selftests/iommu/iommufd_utils.h | 44 ++ 10 files changed, 741 insertions(+), 63 deletions(-)
base-commit: fc882154e421f82677925d33577226e776bb07a4
Add IOPT_ADDRESS_DMABUF to the iopt_pages and the basic infrastructure to create an iopt_pages from a struct dma_buf *.
DMABUF pages are not supported for accesses, and for now can only be used with the VFIO DMABUF exporter.
The overall flow will be similar to memfd where the user can pass in a DMABUF file descriptor to IOMMU_IOAS_MAP_FILE and create an area and pages. Like other areas it can be copied and otherwise manipulated, though there is little point in doing so.
There is no pinned page accounting done for DMABUF maps.
The DMABUF attachment exists so long as the dmabuf is mapped into an IOAS, even if the IOAS is not mapped to any domains.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/io_pagetable.c | 3 + drivers/iommu/iommufd/io_pagetable.h | 24 ++++- drivers/iommu/iommufd/iommufd_private.h | 2 + drivers/iommu/iommufd/main.c | 10 ++ drivers/iommu/iommufd/pages.c | 133 +++++++++++++++++++++++- 5 files changed, 168 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index c0360c450880b8..b3cf3825a88c7f 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -284,6 +284,9 @@ static int iopt_alloc_area_pages(struct io_pagetable *iopt, case IOPT_ADDRESS_FILE: start = elm->start_byte + elm->pages->start; break; + case IOPT_ADDRESS_DMABUF: + start = elm->start_byte + elm->pages->dmabuf.start; + break; } rc = iopt_alloc_iova(iopt, dst_iova, start, length); if (rc) diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index b6064f4ce4af91..26a7cb1668e8db 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -13,6 +13,7 @@ #include "iommufd_private.h"
struct iommu_domain; +struct dma_buf;
/* * Each io_pagetable is composed of intervals of areas which cover regions of @@ -179,7 +180,14 @@ enum {
enum iopt_address_type { IOPT_ADDRESS_USER = 0, - IOPT_ADDRESS_FILE = 1, + IOPT_ADDRESS_FILE, + IOPT_ADDRESS_DMABUF, +}; + +struct iopt_pages_dmabuf { + struct dma_buf_attachment *attach; + struct phys_vec phys; + unsigned long start; };
/* @@ -209,6 +217,8 @@ struct iopt_pages { struct file *file; unsigned long start; }; + /* IOPT_ADDRESS_DMABUF */ + struct iopt_pages_dmabuf dmabuf; }; bool writable:1; u8 account_mode; @@ -220,10 +230,22 @@ struct iopt_pages { struct rb_root_cached domains_itree; };
+static inline bool iopt_is_dmabuf(struct iopt_pages *pages) +{ + if (!IS_ENABLED(CONFIG_DMA_SHARED_BUFFER)) + return false; + return pages->type == IOPT_ADDRESS_DMABUF; +} + struct iopt_pages *iopt_alloc_user_pages(void __user *uptr, unsigned long length, bool writable); struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start, unsigned long length, bool writable); +struct iopt_pages *iopt_alloc_dmabuf_pages(struct iommufd_ctx *ictx, + struct dma_buf *dmabuf, + unsigned long start_byte, + unsigned long start, + unsigned long length, bool writable); void iopt_release_pages(struct kref *kref); static inline void iopt_put_pages(struct iopt_pages *pages) { diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 627f9b78483a0e..10ee3510312132 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -504,6 +504,8 @@ void iommufd_device_pre_destroy(struct iommufd_object *obj); void iommufd_device_destroy(struct iommufd_object *obj); int iommufd_get_hw_info(struct iommufd_ucmd *ucmd);
+struct device *iommufd_global_device(void); + struct iommufd_access { struct iommufd_object obj; struct iommufd_ctx *ictx; diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index ce775fbbae94e7..5cc4b08c25f585 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -751,6 +751,15 @@ static struct miscdevice vfio_misc_dev = { .mode = 0666, };
+/* + * Used only by DMABUF, returns a valid struct device to use as a dummy struct + * device for attachment. + */ +struct device *iommufd_global_device(void) +{ + return iommu_misc_dev.this_device; +} + static int __init iommufd_init(void) { int ret; @@ -794,5 +803,6 @@ MODULE_ALIAS("devname:vfio/vfio"); #endif MODULE_IMPORT_NS("IOMMUFD_INTERNAL"); MODULE_IMPORT_NS("IOMMUFD"); +MODULE_IMPORT_NS("DMA_BUF"); MODULE_DESCRIPTION("I/O Address Space Management for passthrough devices"); MODULE_LICENSE("GPL"); diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index c3433b84556172..4468ef3510dbee 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -45,6 +45,8 @@ * last_iova + 1 can overflow. An iopt_pages index will always be much less than * ULONG_MAX so last_index + 1 cannot overflow. */ +#include <linux/dma-buf.h> +#include <linux/dma-resv.h> #include <linux/file.h> #include <linux/highmem.h> #include <linux/iommu.h> @@ -53,6 +55,7 @@ #include <linux/overflow.h> #include <linux/slab.h> #include <linux/sched/mm.h> +#include <linux/vfio_pci_core.h>
#include "double_span.h" #include "io_pagetable.h" @@ -272,6 +275,7 @@ struct pfn_batch { unsigned int end; unsigned int total_pfns; }; +enum { MAX_NPFNS = type_max(typeof(((struct pfn_batch *)0)->npfns[0])) };
static void batch_clear(struct pfn_batch *batch) { @@ -350,7 +354,6 @@ static void batch_destroy(struct pfn_batch *batch, void *backup) static bool batch_add_pfn_num(struct pfn_batch *batch, unsigned long pfn, u32 nr) { - const unsigned int MAX_NPFNS = type_max(typeof(*batch->npfns)); unsigned int end = batch->end;
if (end && pfn == batch->pfns[end - 1] + batch->npfns[end - 1] && @@ -1360,6 +1363,121 @@ struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start, return pages; }
+static void iopt_revoke_notify(struct dma_buf_attachment *attach) +{ + struct iopt_pages *pages = attach->importer_priv; + + guard(mutex)(&pages->mutex); + pages->dmabuf.phys.len = 0; +} + +static struct dma_buf_attach_ops iopt_dmabuf_attach_revoke_ops = { + .allow_peer2peer = true, + .move_notify = iopt_revoke_notify, +}; + +/* + * iommufd and vfio have a circular dependency. Future work for a phys + * based private interconnect will remove this. + */ +static int +sym_vfio_pci_dma_buf_iommufd_map(struct dma_buf_attachment *attachment, + struct phys_vec *phys) +{ + typeof(&vfio_pci_dma_buf_iommufd_map) fn; + int rc; + + if (!IS_ENABLED(CONFIG_VFIO_PCI_DMABUF)) + return -EOPNOTSUPP; + + fn = symbol_get(vfio_pci_dma_buf_iommufd_map); + if (!fn) + return -EOPNOTSUPP; + rc = fn(attachment, phys); + symbol_put(vfio_pci_dma_buf_iommufd_map); + return rc; +} + +static int iopt_map_dmabuf(struct iommufd_ctx *ictx, struct iopt_pages *pages, + struct dma_buf *dmabuf) +{ + struct dma_buf_attachment *attach; + int rc; + + attach = dma_buf_dynamic_attach(dmabuf, iommufd_global_device(), + &iopt_dmabuf_attach_revoke_ops, pages); + if (IS_ERR(attach)) + return PTR_ERR(attach); + + dma_resv_lock(dmabuf->resv, NULL); + /* + * Lock ordering requires the mutex to be taken inside the reservation, + * make sure lockdep sees this. + */ + if (IS_ENABLED(CONFIG_LOCKDEP)) { + mutex_lock(&pages->mutex); + mutex_unlock(&pages->mutex); + } + + rc = sym_vfio_pci_dma_buf_iommufd_map(attach, &pages->dmabuf.phys); + if (rc) + goto err_detach; + + dma_resv_unlock(dmabuf->resv); + + /* On success iopt_release_pages() will detach and put the dmabuf. */ + pages->dmabuf.attach = attach; + return 0; + +err_detach: + dma_resv_unlock(dmabuf->resv); + dma_buf_detach(dmabuf, attach); + return rc; +} + +struct iopt_pages *iopt_alloc_dmabuf_pages(struct iommufd_ctx *ictx, + struct dma_buf *dmabuf, + unsigned long start_byte, + unsigned long start, + unsigned long length, bool writable) +{ + static struct lock_class_key pages_dmabuf_mutex_key; + struct iopt_pages *pages; + int rc; + + if (!IS_ENABLED(CONFIG_DMA_SHARED_BUFFER)) + return ERR_PTR(-EOPNOTSUPP); + + if (dmabuf->size <= (start + length - 1) || + length / PAGE_SIZE >= MAX_NPFNS) + return ERR_PTR(-EINVAL); + + pages = iopt_alloc_pages(start_byte, length, writable); + if (IS_ERR(pages)) + return pages; + + /* + * The mmap_lock can be held when obtaining the dmabuf reservation lock + * which creates a locking cycle with the pages mutex which is held + * while obtaining the mmap_lock. This locking path is not present for + * IOPT_ADDRESS_DMABUF so split the lock class. + */ + lockdep_set_class(&pages->mutex, &pages_dmabuf_mutex_key); + + /* dmabuf does not use pinned page accounting. */ + pages->account_mode = IOPT_PAGES_ACCOUNT_NONE; + pages->type = IOPT_ADDRESS_DMABUF; + pages->dmabuf.start = start - start_byte; + + rc = iopt_map_dmabuf(ictx, pages, dmabuf); + if (rc) { + iopt_put_pages(pages); + return ERR_PTR(rc); + } + + return pages; +} + void iopt_release_pages(struct kref *kref) { struct iopt_pages *pages = container_of(kref, struct iopt_pages, kref); @@ -1372,8 +1490,14 @@ void iopt_release_pages(struct kref *kref) mutex_destroy(&pages->mutex); put_task_struct(pages->source_task); free_uid(pages->source_user); - if (pages->type == IOPT_ADDRESS_FILE) + if (iopt_is_dmabuf(pages) && pages->dmabuf.attach) { + struct dma_buf *dmabuf = pages->dmabuf.attach->dmabuf; + + dma_buf_detach(dmabuf, pages->dmabuf.attach); + dma_buf_put(dmabuf); + } else if (pages->type == IOPT_ADDRESS_FILE) { fput(pages->file); + } kfree(pages); }
@@ -2031,7 +2155,10 @@ int iopt_pages_rw_access(struct iopt_pages *pages, unsigned long start_byte, if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable) return -EPERM;
- if (pages->type == IOPT_ADDRESS_FILE) + if (iopt_is_dmabuf(pages)) + return -EINVAL; + + if (pages->type != IOPT_ADDRESS_USER) return iopt_pages_rw_slow(pages, start_index, last_index, start_byte % PAGE_SIZE, data, length, flags);
Once a DMABUF is revoked the domain will be unmapped under the pages mutex. Double unmapping will trigger a WARN, and mapping while revoked will fail.
Check for revoked DMABUFs along all the map and unmap paths to resolve this. Ensure that map/unmap is always done under the pages mutex so it is synchronized with the revoke notifier.
If a revoke happens between allocating the iopt_pages and the population to a domain then the population will succeed, and leave things unmapped as though revoke had happened immediately after.
Currently there is no way to repopulate the domains. Userspace is expected to know if it is going to do something that would trigger revoke (eg if it is about to do a FLR) then it should go and remove the DMABUF mappings before and put the back after. The revoke is only to protect the kernel from mis-behaving userspace.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/io_pagetable.c | 11 +++++- drivers/iommu/iommufd/io_pagetable.h | 8 +++++ drivers/iommu/iommufd/pages.c | 54 +++++++++++++++++----------- 3 files changed, 52 insertions(+), 21 deletions(-)
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index b3cf3825a88c7f..38c5fdc6c82128 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -970,9 +970,14 @@ static void iopt_unfill_domain(struct io_pagetable *iopt, WARN_ON(!area->storage_domain); if (area->storage_domain == domain) area->storage_domain = storage_domain; + if (iopt_is_dmabuf(pages)) { + if (!iopt_dmabuf_revoked(pages)) + iopt_area_unmap_domain(area, domain); + } mutex_unlock(&pages->mutex);
- iopt_area_unmap_domain(area, domain); + if (!iopt_is_dmabuf(pages)) + iopt_area_unmap_domain(area, domain); } return; } @@ -1261,6 +1266,10 @@ static int iopt_area_split(struct iopt_area *area, unsigned long iova) if (!pages || area->prevent_access) return -EBUSY;
+ /* Maintaining the domains_itree below is a bit complicated */ + if (iopt_is_dmabuf(pages)) + return -EOPNOTSUPP; + if (new_start & (alignment - 1) || iopt_area_start_byte(area, new_start) & (alignment - 1)) return -EINVAL; diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index 26a7cb1668e8db..759ebf66265df5 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -237,6 +237,14 @@ static inline bool iopt_is_dmabuf(struct iopt_pages *pages) return pages->type == IOPT_ADDRESS_DMABUF; }
+static inline bool iopt_dmabuf_revoked(struct iopt_pages *pages) +{ + lockdep_assert_held(&pages->mutex); + if (iopt_is_dmabuf(pages)) + return pages->dmabuf.phys.len == 0; + return false; +} + struct iopt_pages *iopt_alloc_user_pages(void __user *uptr, unsigned long length, bool writable); struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start, diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index 4468ef3510dbee..ca27ad3a3168e5 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -1650,6 +1650,9 @@ void iopt_area_unmap_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) { + if (iopt_dmabuf_revoked(pages)) + return; + __iopt_area_unfill_domain(area, pages, domain, iopt_area_last_index(area)); } @@ -1670,6 +1673,9 @@ int iopt_area_fill_domain(struct iopt_area *area, struct iommu_domain *domain)
lockdep_assert_held(&area->pages->mutex);
+ if (iopt_dmabuf_revoked(area->pages)) + return 0; + rc = pfn_reader_first(&pfns, area->pages, iopt_area_index(area), iopt_area_last_index(area)); if (rc) @@ -1729,33 +1735,38 @@ int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages) 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; + if (!iopt_dmabuf_revoked(pages)) { + 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)) { - done_first_end_index = pfns.batch_end_index; - done_all_end_index = pfns.batch_start_index; - xa_for_each(&area->iopt->domains, index, domain) { - rc = batch_to_domain(&pfns.batch, domain, area, - pfns.batch_start_index); + while (!pfn_reader_done(&pfns)) { + done_first_end_index = pfns.batch_end_index; + done_all_end_index = pfns.batch_start_index; + 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; + } + done_all_end_index = done_first_end_index; + + rc = pfn_reader_next(&pfns); if (rc) goto out_unmap; } - done_all_end_index = done_first_end_index; - - rc = pfn_reader_next(&pfns); + rc = pfn_reader_update_pinned(&pfns); if (rc) goto out_unmap; + + pfn_reader_destroy(&pfns); } - 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; + mutex_unlock(&pages->mutex); + return 0;
out_unmap: pfn_reader_release_pins(&pfns); @@ -1782,7 +1793,6 @@ int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages) end_index); } } -out_destroy: pfn_reader_destroy(&pfns); out_unlock: mutex_unlock(&pages->mutex); @@ -1809,11 +1819,15 @@ void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages) if (!area->storage_domain) goto out_unlock;
- xa_for_each(&iopt->domains, index, domain) - if (domain != area->storage_domain) + xa_for_each(&iopt->domains, index, domain) { + if (domain == area->storage_domain) + continue; + + if (!iopt_dmabuf_revoked(pages)) iopt_area_unmap_domain_range( area, domain, iopt_area_index(area), iopt_area_last_index(area)); + }
if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) WARN_ON(RB_EMPTY_NODE(&area->pages_node.rb));
When connected to VFIO, the only DMABUF exporter that is accepted, the move_notify callback will be made when VFIO wants to remove access to the MMIO. This is being called revoke.
Wire up revoke to go through all the iommu_domain's that have mapped the DMABUF and unmap them.
The locking here is unpleasant, since the existing locking scheme was designed to come from the iopt through the area to the pages we cannot use pages as starting point for the locking. There is no way to obtain the domains_rwsem before obtaining the pages mutex to reliably use the existing domains_itree.
Solve this problem by adding a new tracking structure just for DMABUF revoke. Record a linked list of areas and domains inside the pages mutex. Clean the entries on the list during revoke. The map/unmaps are now all done under a pages mutex while updating the tracking linked list so nothing can get out of sync. Only one lock is required for revoke processing.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/io_pagetable.c | 12 +++ drivers/iommu/iommufd/io_pagetable.h | 17 +++++ drivers/iommu/iommufd/pages.c | 106 ++++++++++++++++++++++++++- 3 files changed, 134 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index 38c5fdc6c82128..d0539bbd6771ea 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -973,6 +973,7 @@ static void iopt_unfill_domain(struct io_pagetable *iopt, if (iopt_is_dmabuf(pages)) { if (!iopt_dmabuf_revoked(pages)) iopt_area_unmap_domain(area, domain); + iopt_dmabuf_untrack_domain(pages, area, domain); } mutex_unlock(&pages->mutex);
@@ -994,6 +995,8 @@ static void iopt_unfill_domain(struct io_pagetable *iopt, WARN_ON(area->storage_domain != domain); area->storage_domain = NULL; iopt_area_unfill_domain(area, pages, domain); + if (iopt_is_dmabuf(pages)) + iopt_dmabuf_untrack_domain(pages, area, domain); mutex_unlock(&pages->mutex); } } @@ -1024,8 +1027,15 @@ static int iopt_fill_domain(struct io_pagetable *iopt, continue;
mutex_lock(&pages->mutex); + if (iopt_is_dmabuf(pages)) { + rc = iopt_dmabuf_track_domain(pages, area, domain); + if (rc) + goto out_unfill; + } rc = iopt_area_fill_domain(area, domain); if (rc) { + if (iopt_is_dmabuf(pages)) + iopt_dmabuf_untrack_domain(pages, area, domain); mutex_unlock(&pages->mutex); goto out_unfill; } @@ -1056,6 +1066,8 @@ static int iopt_fill_domain(struct io_pagetable *iopt, area->storage_domain = NULL; } iopt_area_unfill_domain(area, pages, domain); + if (iopt_is_dmabuf(pages)) + iopt_dmabuf_untrack_domain(pages, area, domain); mutex_unlock(&pages->mutex); } return rc; diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index 759ebf66265df5..2d5b8778735a56 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -70,6 +70,16 @@ void iopt_area_unfill_domain(struct iopt_area *area, struct iopt_pages *pages, void iopt_area_unmap_domain(struct iopt_area *area, struct iommu_domain *domain);
+int iopt_dmabuf_track_domain(struct iopt_pages *pages, struct iopt_area *area, + struct iommu_domain *domain); +void iopt_dmabuf_untrack_domain(struct iopt_pages *pages, + struct iopt_area *area, + struct iommu_domain *domain); +int iopt_dmabuf_track_all_domains(struct iopt_area *area, + struct iopt_pages *pages); +void iopt_dmabuf_untrack_all_domains(struct iopt_area *area, + struct iopt_pages *pages); + static inline unsigned long iopt_area_index(struct iopt_area *area) { return area->pages_node.start; @@ -184,10 +194,17 @@ enum iopt_address_type { IOPT_ADDRESS_DMABUF, };
+struct iopt_pages_dmabuf_track { + struct iommu_domain *domain; + struct iopt_area *area; + struct list_head elm; +}; + struct iopt_pages_dmabuf { struct dma_buf_attachment *attach; struct phys_vec phys; unsigned long start; + struct list_head tracker; };
/* diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index ca27ad3a3168e5..463d6340de1dcb 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -1366,8 +1366,19 @@ struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start, static void iopt_revoke_notify(struct dma_buf_attachment *attach) { struct iopt_pages *pages = attach->importer_priv; + struct iopt_pages_dmabuf_track *track;
guard(mutex)(&pages->mutex); + if (iopt_dmabuf_revoked(pages)) + return; + + list_for_each_entry(track, &pages->dmabuf.tracker, elm) { + struct iopt_area *area = track->area; + + iopt_area_unmap_domain_range(area, track->domain, + iopt_area_index(area), + iopt_area_last_index(area)); + } pages->dmabuf.phys.len = 0; }
@@ -1468,6 +1479,7 @@ struct iopt_pages *iopt_alloc_dmabuf_pages(struct iommufd_ctx *ictx, pages->account_mode = IOPT_PAGES_ACCOUNT_NONE; pages->type = IOPT_ADDRESS_DMABUF; pages->dmabuf.start = start - start_byte; + INIT_LIST_HEAD(&pages->dmabuf.tracker);
rc = iopt_map_dmabuf(ictx, pages, dmabuf); if (rc) { @@ -1478,6 +1490,86 @@ struct iopt_pages *iopt_alloc_dmabuf_pages(struct iommufd_ctx *ictx, return pages; }
+int iopt_dmabuf_track_domain(struct iopt_pages *pages, struct iopt_area *area, + struct iommu_domain *domain) +{ + struct iopt_pages_dmabuf_track *track; + + lockdep_assert_held(&pages->mutex); + if (WARN_ON(!iopt_is_dmabuf(pages))) + return -EINVAL; + + list_for_each_entry(track, &pages->dmabuf.tracker, elm) + if (WARN_ON(track->domain == domain && track->area == area)) + return -EINVAL; + + track = kzalloc(sizeof(*track), GFP_KERNEL); + if (!track) + return -ENOMEM; + track->domain = domain; + track->area = area; + list_add_tail(&track->elm, &pages->dmabuf.tracker); + + return 0; +} + +void iopt_dmabuf_untrack_domain(struct iopt_pages *pages, + struct iopt_area *area, + struct iommu_domain *domain) +{ + struct iopt_pages_dmabuf_track *track; + + lockdep_assert_held(&pages->mutex); + WARN_ON(!iopt_is_dmabuf(pages)); + + list_for_each_entry(track, &pages->dmabuf.tracker, elm) { + if (track->domain == domain && track->area == area) { + list_del(&track->elm); + kfree(track); + return; + } + } + WARN_ON(true); +} + +int iopt_dmabuf_track_all_domains(struct iopt_area *area, + struct iopt_pages *pages) +{ + struct iopt_pages_dmabuf_track *track; + struct iommu_domain *domain; + unsigned long index; + int rc; + + list_for_each_entry(track, &pages->dmabuf.tracker, elm) + if (WARN_ON(track->area == area)) + return -EINVAL; + + xa_for_each(&area->iopt->domains, index, domain) { + rc = iopt_dmabuf_track_domain(pages, area, domain); + if (rc) + goto err_untrack; + } + return 0; +err_untrack: + iopt_dmabuf_untrack_all_domains(area, pages); + return rc; +} + +void iopt_dmabuf_untrack_all_domains(struct iopt_area *area, + struct iopt_pages *pages) +{ + struct iopt_pages_dmabuf_track *track; + struct iopt_pages_dmabuf_track *tmp; + + list_for_each_entry_safe(track, tmp, &pages->dmabuf.tracker, + elm) { + if (track->area == area) { + list_del(&track->elm); + kfree(track); + } + } +} + void iopt_release_pages(struct kref *kref) { struct iopt_pages *pages = container_of(kref, struct iopt_pages, kref); @@ -1495,6 +1587,7 @@ void iopt_release_pages(struct kref *kref)
dma_buf_detach(dmabuf, pages->dmabuf.attach); dma_buf_put(dmabuf); + WARN_ON(!list_empty(&pages->dmabuf.tracker)); } else if (pages->type == IOPT_ADDRESS_FILE) { fput(pages->file); } @@ -1735,11 +1828,17 @@ int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages) return 0;
mutex_lock(&pages->mutex); + if (iopt_is_dmabuf(pages)) { + rc = iopt_dmabuf_track_all_domains(area, pages); + if (rc) + goto out_unlock; + } + if (!iopt_dmabuf_revoked(pages)) { rc = pfn_reader_first(&pfns, pages, iopt_area_index(area), iopt_area_last_index(area)); if (rc) - goto out_unlock; + goto out_untrack;
while (!pfn_reader_done(&pfns)) { done_first_end_index = pfns.batch_end_index; @@ -1794,6 +1893,9 @@ int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages) } } pfn_reader_destroy(&pfns); +out_untrack: + if (iopt_is_dmabuf(pages)) + iopt_dmabuf_untrack_all_domains(area, pages); out_unlock: mutex_unlock(&pages->mutex); return rc; @@ -1833,6 +1935,8 @@ void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages) WARN_ON(RB_EMPTY_NODE(&area->pages_node.rb)); interval_tree_remove(&area->pages_node, &pages->domains_itree); iopt_area_unfill_domain(area, pages, area->storage_domain); + if (iopt_is_dmabuf(pages)) + iopt_dmabuf_untrack_all_domains(area, pages); area->storage_domain = NULL; out_unlock: mutex_unlock(&pages->mutex);
On Mon, Oct 27, 2025 at 02:31:02PM -0300, Jason Gunthorpe wrote:
@@ -1024,8 +1027,15 @@ static int iopt_fill_domain(struct io_pagetable *iopt, continue; mutex_lock(&pages->mutex);
if (iopt_is_dmabuf(pages)) {rc = iopt_dmabuf_track_domain(pages, area, domain);if (rc)goto out_unfill;
I think this error path results in locking pages->mutex recursively. Needs a mutex_unlock(&pages->mutex)?
}if (iopt_is_dmabuf(pages))iopt_dmabuf_untrack_domain(pages, area, domain); mutex_unlock(&pages->mutex); goto out_unfill;
On Tue, Nov 04, 2025 at 11:58:24PM -0800, Alex Mastro wrote:
On Mon, Oct 27, 2025 at 02:31:02PM -0300, Jason Gunthorpe wrote:
@@ -1024,8 +1027,15 @@ static int iopt_fill_domain(struct io_pagetable *iopt, continue; mutex_lock(&pages->mutex);
if (iopt_is_dmabuf(pages)) {rc = iopt_dmabuf_track_domain(pages, area, domain);if (rc)goto out_unfill;I think this error path results in locking pages->mutex recursively. Needs a mutex_unlock(&pages->mutex)?
Yes, let's use a guard then:
--- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -1056,7 +1056,7 @@ static int iopt_fill_domain(struct io_pagetable *iopt, if (!pages) continue;
- mutex_lock(&pages->mutex); + guard(mutex)(&pages->mutex); if (iopt_is_dmabuf(pages)) { rc = iopt_dmabuf_track_domain(pages, area, domain); if (rc) @@ -1066,7 +1066,6 @@ static int iopt_fill_domain(struct io_pagetable *iopt, if (rc) { if (iopt_is_dmabuf(pages)) iopt_dmabuf_untrack_domain(pages, area, domain); - mutex_unlock(&pages->mutex); goto out_unfill; } if (!area->storage_domain) {
Thanks, Jason
Addresses intended for MMIO should be propagated through to the iommu with the IOMMU_MMIO flag set.
Keep track in the batch if all the pfns are cachable or mmio and flush the batch out of it ever needs to be changed. Switch to IOMMU_MMIO if the batch is MMIO when mapping the iommu.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/pages.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-)
diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index 463d6340de1dcb..caafb5faf55a12 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -261,6 +261,11 @@ static struct iopt_area *iopt_pages_find_domain_area(struct iopt_pages *pages, return container_of(node, struct iopt_area, pages_node); }
+enum batch_kind { + BATCH_CPU_MEMORY = 0, + BATCH_MMIO, +}; + /* * A simple datastructure to hold a vector of PFNs, optimized for contiguous * PFNs. This is used as a temporary holding memory for shuttling pfns from one @@ -274,6 +279,7 @@ struct pfn_batch { unsigned int array_size; unsigned int end; unsigned int total_pfns; + enum batch_kind kind; }; enum { MAX_NPFNS = type_max(typeof(((struct pfn_batch *)0)->npfns[0])) };
@@ -352,10 +358,17 @@ static void batch_destroy(struct pfn_batch *batch, void *backup) }
static bool batch_add_pfn_num(struct pfn_batch *batch, unsigned long pfn, - u32 nr) + u32 nr, enum batch_kind kind) { unsigned int end = batch->end;
+ if (batch->kind != kind) { + /* One kind per batch */ + if (batch->end != 0) + return false; + batch->kind = kind; + } + if (end && pfn == batch->pfns[end - 1] + batch->npfns[end - 1] && nr <= MAX_NPFNS - batch->npfns[end - 1]) { batch->npfns[end - 1] += nr; @@ -382,7 +395,7 @@ static void batch_remove_pfn_num(struct pfn_batch *batch, unsigned long nr) /* true if the pfn was added, false otherwise */ static bool batch_add_pfn(struct pfn_batch *batch, unsigned long pfn) { - return batch_add_pfn_num(batch, pfn, 1); + return batch_add_pfn_num(batch, pfn, 1, BATCH_CPU_MEMORY); }
/* @@ -495,6 +508,7 @@ static int batch_to_domain(struct pfn_batch *batch, struct iommu_domain *domain, { bool disable_large_pages = area->iopt->disable_large_pages; unsigned long last_iova = iopt_area_last_iova(area); + int iommu_prot = area->iommu_prot; unsigned int page_offset = 0; unsigned long start_iova; unsigned long next_iova; @@ -502,6 +516,11 @@ static int batch_to_domain(struct pfn_batch *batch, struct iommu_domain *domain, unsigned long iova; int rc;
+ if (batch->kind == BATCH_MMIO) { + iommu_prot &= ~IOMMU_CACHE; + iommu_prot |= IOMMU_MMIO; + } + /* The first index might be a partial page */ if (start_index == iopt_area_index(area)) page_offset = area->page_offset; @@ -515,11 +534,11 @@ static int batch_to_domain(struct pfn_batch *batch, struct iommu_domain *domain, rc = batch_iommu_map_small( domain, iova, PFN_PHYS(batch->pfns[cur]) + page_offset, - next_iova - iova, area->iommu_prot); + next_iova - iova, iommu_prot); else rc = iommu_map(domain, iova, PFN_PHYS(batch->pfns[cur]) + page_offset, - next_iova - iova, area->iommu_prot, + next_iova - iova, iommu_prot, GFP_KERNEL_ACCOUNT); if (rc) goto err_unmap; @@ -655,7 +674,7 @@ static int batch_from_folios(struct pfn_batch *batch, struct folio ***folios_p, nr = min(nr, npages); npages -= nr;
- if (!batch_add_pfn_num(batch, pfn, nr)) + if (!batch_add_pfn_num(batch, pfn, nr, BATCH_CPU_MEMORY)) break; if (nr > 1) { rc = folio_add_pins(folio, nr - 1);
Make another sub implementation of pfn_reader for DMABUF. This version will fill the batch using the struct phys_vec recorded during the attachment.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/pages.c | 70 +++++++++++++++++++++++++++++++---- 1 file changed, 63 insertions(+), 7 deletions(-)
diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index caafb5faf55a12..9c017064322b41 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -1076,6 +1076,40 @@ static int pfn_reader_user_update_pinned(struct pfn_reader_user *user, return iopt_pages_update_pinned(pages, npages, inc, user); }
+struct pfn_reader_dmabuf { + struct phys_vec phys; + unsigned long start_offset; +}; + +static int pfn_reader_dmabuf_init(struct pfn_reader_dmabuf *dmabuf, + struct iopt_pages *pages) +{ + /* Callers must not get here if the dmabuf was already revoked */ + if (WARN_ON(iopt_dmabuf_revoked(pages))) + return -EINVAL; + + dmabuf->phys = pages->dmabuf.phys; + dmabuf->start_offset = pages->dmabuf.start; + return 0; +} + +static int pfn_reader_fill_dmabuf(struct pfn_reader_dmabuf *dmabuf, + struct pfn_batch *batch, + unsigned long start_index, + unsigned long last_index) +{ + unsigned long start = dmabuf->start_offset + start_index * PAGE_SIZE; + + /* + * This works in PAGE_SIZE indexes, if the dmabuf is sliced and + * starts/ends at a sub page offset then the batch to domain code will + * adjust it. + */ + batch_add_pfn_num(batch, PHYS_PFN(dmabuf->phys.paddr + start), + last_index - start_index + 1, BATCH_MMIO); + return 0; +} + /* * PFNs are stored in three places, in order of preference: * - The iopt_pages xarray. This is only populated if there is a @@ -1094,7 +1128,10 @@ struct pfn_reader { unsigned long batch_end_index; unsigned long last_index;
- struct pfn_reader_user user; + union { + struct pfn_reader_user user; + struct pfn_reader_dmabuf dmabuf; + }; };
static int pfn_reader_update_pinned(struct pfn_reader *pfns) @@ -1130,7 +1167,7 @@ static int pfn_reader_fill_span(struct pfn_reader *pfns) { struct interval_tree_double_span_iter *span = &pfns->span; unsigned long start_index = pfns->batch_end_index; - struct pfn_reader_user *user = &pfns->user; + struct pfn_reader_user *user; unsigned long npages; struct iopt_area *area; int rc; @@ -1162,8 +1199,13 @@ static int pfn_reader_fill_span(struct pfn_reader *pfns) return 0; }
- if (start_index >= pfns->user.upages_end) { - rc = pfn_reader_user_pin(&pfns->user, pfns->pages, start_index, + if (iopt_is_dmabuf(pfns->pages)) + return pfn_reader_fill_dmabuf(&pfns->dmabuf, &pfns->batch, + start_index, span->last_hole); + + user = &pfns->user; + if (start_index >= user->upages_end) { + rc = pfn_reader_user_pin(user, pfns->pages, start_index, span->last_hole); if (rc) return rc; @@ -1231,7 +1273,10 @@ static int pfn_reader_init(struct pfn_reader *pfns, struct iopt_pages *pages, pfns->batch_start_index = start_index; pfns->batch_end_index = start_index; pfns->last_index = last_index; - pfn_reader_user_init(&pfns->user, pages); + if (iopt_is_dmabuf(pages)) + pfn_reader_dmabuf_init(&pfns->dmabuf, pages); + else + pfn_reader_user_init(&pfns->user, pages); rc = batch_init(&pfns->batch, last_index - start_index + 1); if (rc) return rc; @@ -1252,8 +1297,12 @@ static int pfn_reader_init(struct pfn_reader *pfns, struct iopt_pages *pages, static void pfn_reader_release_pins(struct pfn_reader *pfns) { struct iopt_pages *pages = pfns->pages; - struct pfn_reader_user *user = &pfns->user; + struct pfn_reader_user *user;
+ if (iopt_is_dmabuf(pages)) + return; + + user = &pfns->user; if (user->upages_end > pfns->batch_end_index) { /* Any pages not transferred to the batch are just unpinned */
@@ -1283,7 +1332,8 @@ static void pfn_reader_destroy(struct pfn_reader *pfns) struct iopt_pages *pages = pfns->pages;
pfn_reader_release_pins(pfns); - pfn_reader_user_destroy(&pfns->user, pfns->pages); + if (!iopt_is_dmabuf(pfns->pages)) + pfn_reader_user_destroy(&pfns->user, pfns->pages); batch_destroy(&pfns->batch, NULL); WARN_ON(pages->last_npinned != pages->npinned); } @@ -1687,6 +1737,12 @@ static void __iopt_area_unfill_domain(struct iopt_area *area,
lockdep_assert_held(&pages->mutex);
+ if (iopt_is_dmabuf(pages)) { + iopt_area_unmap_domain_range(area, domain, start_index, + last_index); + return; + } + /* * For security we must not unpin something that is still DMA mapped, * so this must unmap any IOVA before we go ahead and unpin the pages.
Since dmabuf only has APIs that work on a int fd and not a struct file *, pass the fd deeper into the call chain so we can use the dmabuf APIs as is.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/io_pagetable.c | 15 +++++++++++---- drivers/iommu/iommufd/ioas.c | 8 +------- drivers/iommu/iommufd/iommufd_private.h | 2 +- 3 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index d0539bbd6771ea..0ab609509a81a4 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -10,6 +10,7 @@ */ #include <linux/err.h> #include <linux/errno.h> +#include <linux/file.h> #include <linux/iommu.h> #include <linux/iommufd.h> #include <linux/lockdep.h> @@ -471,21 +472,27 @@ int iopt_map_user_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, * @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 - * @file: file to map + * @fd: fdno of a file to map * @start: map file starting at this byte offset * @length: Number of bytes to map * @iommu_prot: Combination of IOMMU_READ/WRITE/etc bits for the mapping * @flags: IOPT_ALLOC_IOVA or zero */ int iopt_map_file_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, - unsigned long *iova, struct file *file, - unsigned long start, unsigned long length, - int iommu_prot, unsigned int flags) + unsigned long *iova, int fd, unsigned long start, + unsigned long length, int iommu_prot, + unsigned int flags) { struct iopt_pages *pages; + struct file *file; + + file = fget(fd); + if (!file) + return -EBADF;
pages = iopt_alloc_file_pages(file, start, length, iommu_prot & IOMMU_WRITE); + fput(file); if (IS_ERR(pages)) return PTR_ERR(pages); return iopt_map_common(ictx, iopt, pages, iova, length, diff --git a/drivers/iommu/iommufd/ioas.c b/drivers/iommu/iommufd/ioas.c index 1542c5fd10a85c..0dee38d7252df4 100644 --- a/drivers/iommu/iommufd/ioas.c +++ b/drivers/iommu/iommufd/ioas.c @@ -207,7 +207,6 @@ int iommufd_ioas_map_file(struct iommufd_ucmd *ucmd) unsigned long iova = cmd->iova; struct iommufd_ioas *ioas; unsigned int flags = 0; - struct file *file; int rc;
if (cmd->flags & @@ -229,11 +228,7 @@ int iommufd_ioas_map_file(struct iommufd_ucmd *ucmd) if (!(cmd->flags & IOMMU_IOAS_MAP_FIXED_IOVA)) flags = IOPT_ALLOC_IOVA;
- file = fget(cmd->fd); - if (!file) - return -EBADF; - - rc = iopt_map_file_pages(ucmd->ictx, &ioas->iopt, &iova, file, + rc = iopt_map_file_pages(ucmd->ictx, &ioas->iopt, &iova, cmd->fd, cmd->start, cmd->length, conv_iommu_prot(cmd->flags), flags); if (rc) @@ -243,7 +238,6 @@ int iommufd_ioas_map_file(struct iommufd_ucmd *ucmd) rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); out_put: iommufd_put_object(ucmd->ictx, &ioas->obj); - fput(file); return rc; }
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 10ee3510312132..a2786fee7603f5 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -108,7 +108,7 @@ int iopt_map_user_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, unsigned long length, int iommu_prot, unsigned int flags); int iopt_map_file_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, - unsigned long *iova, struct file *file, + unsigned long *iova, int fd, unsigned long start, unsigned long length, int iommu_prot, unsigned int flags); int iopt_map_pages(struct io_pagetable *iopt, struct list_head *pages_list,
Finally call iopt_alloc_dmabuf_pages() if the user passed in a DMABUF through IOMMU_IOAS_MAP_FILE. This makes the feature visible to userspace.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/io_pagetable.c | 43 +++++++++++++++++++++------- drivers/iommu/iommufd/io_pagetable.h | 4 ++- drivers/iommu/iommufd/pages.c | 13 ++++----- 3 files changed, 41 insertions(+), 19 deletions(-)
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index 0ab609509a81a4..b78a44cf54a431 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -8,6 +8,7 @@ * The datastructure uses the iopt_pages to optimize the storage of the PFNs * between the domains and xarray. */ +#include <linux/dma-buf.h> #include <linux/err.h> #include <linux/errno.h> #include <linux/file.h> @@ -484,19 +485,41 @@ int iopt_map_file_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt, unsigned int flags) { struct iopt_pages *pages; - struct file *file; + struct dma_buf *dmabuf; + unsigned long start_byte; + unsigned long last;
- file = fget(fd); - if (!file) - return -EBADF; + if (!length) + return -EINVAL; + if (check_add_overflow(start, length - 1, &last)) + return -EOVERFLOW; + + start_byte = start - ALIGN_DOWN(start, PAGE_SIZE); + dmabuf = dma_buf_get(fd); + if (!IS_ERR(dmabuf)) { + pages = iopt_alloc_dmabuf_pages(ictx, dmabuf, start_byte, start, + length, + iommu_prot & IOMMU_WRITE); + if (IS_ERR(pages)) { + dma_buf_put(dmabuf); + return PTR_ERR(pages); + } + } else { + struct file *file; + + file = fget(fd); + if (!file) + return -EBADF; + + pages = iopt_alloc_file_pages(file, start_byte, start, length, + iommu_prot & IOMMU_WRITE); + fput(file); + if (IS_ERR(pages)) + return PTR_ERR(pages); + }
- pages = iopt_alloc_file_pages(file, start, length, - iommu_prot & IOMMU_WRITE); - fput(file); - if (IS_ERR(pages)) - return PTR_ERR(pages); return iopt_map_common(ictx, iopt, pages, iova, length, - start - pages->start, iommu_prot, flags); + start_byte, iommu_prot, flags); }
struct iova_bitmap_fn_arg { diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index 2d5b8778735a56..7424d9514d4685 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -264,7 +264,9 @@ static inline bool iopt_dmabuf_revoked(struct iopt_pages *pages)
struct iopt_pages *iopt_alloc_user_pages(void __user *uptr, unsigned long length, bool writable); -struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start, +struct iopt_pages *iopt_alloc_file_pages(struct file *file, + unsigned long start_byte, + unsigned long start, unsigned long length, bool writable); struct iopt_pages *iopt_alloc_dmabuf_pages(struct iommufd_ctx *ictx, struct dma_buf *dmabuf, diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index 9c017064322b41..524cd64df8ebab 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -1412,22 +1412,19 @@ struct iopt_pages *iopt_alloc_user_pages(void __user *uptr, return pages; }
-struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start, +struct iopt_pages *iopt_alloc_file_pages(struct file *file, + unsigned long start_byte, + unsigned long start, unsigned long length, bool writable)
{ struct iopt_pages *pages; - unsigned long start_down = ALIGN_DOWN(start, PAGE_SIZE); - unsigned long end;
- if (length && check_add_overflow(start, length - 1, &end)) - return ERR_PTR(-EOVERFLOW); - - pages = iopt_alloc_pages(start - start_down, length, writable); + pages = iopt_alloc_pages(start_byte, length, writable); if (IS_ERR(pages)) return pages; pages->file = get_file(file); - pages->start = start_down; + pages->start = start - start_byte; pages->type = IOPT_ADDRESS_FILE; return pages; }
Basic tests of establishing a dmabuf and revoking it. The selftest kernel side provides a basic small dmabuf for this testing.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/iommu/iommufd/iommufd_private.h | 9 ++ drivers/iommu/iommufd/iommufd_test.h | 10 ++ drivers/iommu/iommufd/pages.c | 4 + drivers/iommu/iommufd/selftest.c | 142 ++++++++++++++++++ tools/testing/selftests/iommu/iommufd.c | 43 ++++++ tools/testing/selftests/iommu/iommufd_utils.h | 44 ++++++ 6 files changed, 252 insertions(+)
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index a2786fee7603f5..d6fddd6054ccfa 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -19,6 +19,7 @@ struct iommu_domain; struct iommu_group; struct iommu_option; struct iommufd_device; +struct dma_buf_attachment;
struct iommufd_sw_msi_map { struct list_head sw_msi_item; @@ -713,6 +714,8 @@ bool iommufd_should_fail(void); int __init iommufd_test_init(void); void iommufd_test_exit(void); bool iommufd_selftest_is_mock_dev(struct device *dev); +int iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment *attachment, + struct phys_vec *phys); #else static inline void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd, unsigned int ioas_id, @@ -734,5 +737,11 @@ static inline bool iommufd_selftest_is_mock_dev(struct device *dev) { return false; } +static inline int +iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment *attachment, + struct phys_vec *phys) +{ + return -EOPNOTSUPP; +} #endif #endif diff --git a/drivers/iommu/iommufd/iommufd_test.h b/drivers/iommu/iommufd/iommufd_test.h index 8fc618b2bcf967..9166c39eb0c8b2 100644 --- a/drivers/iommu/iommufd/iommufd_test.h +++ b/drivers/iommu/iommufd/iommufd_test.h @@ -29,6 +29,8 @@ enum { IOMMU_TEST_OP_PASID_REPLACE, IOMMU_TEST_OP_PASID_DETACH, IOMMU_TEST_OP_PASID_CHECK_HWPT, + IOMMU_TEST_OP_DMABUF_GET, + IOMMU_TEST_OP_DMABUF_REVOKE, };
enum { @@ -176,6 +178,14 @@ struct iommu_test_cmd { __u32 hwpt_id; /* @id is stdev_id */ } pasid_check; + struct { + __u32 length; + __u32 open_flags; + } dmabuf_get; + struct { + __s32 dmabuf_fd; + __u32 revoked; + } dmabuf_revoke; }; __u32 last; }; diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index 524cd64df8ebab..ea9671b5385fff 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -1464,6 +1464,10 @@ sym_vfio_pci_dma_buf_iommufd_map(struct dma_buf_attachment *attachment, typeof(&vfio_pci_dma_buf_iommufd_map) fn; int rc;
+ rc = iommufd_test_dma_buf_iommufd_map(attachment, phys); + if (rc != -EOPNOTSUPP) + return rc; + if (!IS_ENABLED(CONFIG_VFIO_PCI_DMABUF)) return -EOPNOTSUPP;
diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c index de178827a078a9..5da12635a8ba27 100644 --- a/drivers/iommu/iommufd/selftest.c +++ b/drivers/iommu/iommufd/selftest.c @@ -5,6 +5,8 @@ */ #include <linux/anon_inodes.h> #include <linux/debugfs.h> +#include <linux/dma-buf.h> +#include <linux/dma-resv.h> #include <linux/fault-inject.h> #include <linux/file.h> #include <linux/iommu.h> @@ -2031,6 +2033,139 @@ void iommufd_selftest_destroy(struct iommufd_object *obj) } }
+struct iommufd_test_dma_buf { + void *memory; + size_t length; + bool revoked; +}; + +static int iommufd_test_dma_buf_attach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + return 0; +} + +static void iommufd_test_dma_buf_detach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ +} + +static struct sg_table * +iommufd_test_dma_buf_map(struct dma_buf_attachment *attachment, + enum dma_data_direction dir) +{ + return ERR_PTR(-EOPNOTSUPP); +} + +static void iommufd_test_dma_buf_unmap(struct dma_buf_attachment *attachment, + struct sg_table *sgt, + enum dma_data_direction dir) +{ +} + +static void iommufd_test_dma_buf_release(struct dma_buf *dmabuf) +{ + struct iommufd_test_dma_buf *priv = dmabuf->priv; + + kfree(priv); +} + +static const struct dma_buf_ops iommufd_test_dmabuf_ops = { + .attach = iommufd_test_dma_buf_attach, + .detach = iommufd_test_dma_buf_detach, + .map_dma_buf = iommufd_test_dma_buf_map, + .release = iommufd_test_dma_buf_release, + .unmap_dma_buf = iommufd_test_dma_buf_unmap, +}; + +int iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment *attachment, + struct phys_vec *phys) +{ + struct iommufd_test_dma_buf *priv = attachment->dmabuf->priv; + + dma_resv_assert_held(attachment->dmabuf->resv); + + if (attachment->dmabuf->ops != &iommufd_test_dmabuf_ops) + return -EOPNOTSUPP; + + if (priv->revoked) + return -ENODEV; + + phys->paddr = virt_to_phys(priv->memory); + phys->len = priv->length; + return 0; +} + +static int iommufd_test_dmabuf_get(struct iommufd_ucmd *ucmd, + unsigned int open_flags, + size_t len) +{ + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + struct iommufd_test_dma_buf *priv; + struct dma_buf *dmabuf; + int rc; + + len = ALIGN(len, PAGE_SIZE); + if (len == 0 || len > PAGE_SIZE * 512) + return -EINVAL; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->length = len; + priv->memory = kzalloc(len, GFP_KERNEL); + if (!priv->memory) { + rc = -ENOMEM; + goto err_free; + } + + exp_info.ops = &iommufd_test_dmabuf_ops; + exp_info.size = len; + exp_info.flags = open_flags; + exp_info.priv = priv; + + dmabuf = dma_buf_export(&exp_info); + if (IS_ERR(dmabuf)) { + rc = PTR_ERR(dmabuf); + goto err_free; + } + + return dma_buf_fd(dmabuf, open_flags); + +err_free: + kfree(priv->memory); + kfree(priv); + return rc; +} + +static int iommufd_test_dmabuf_revoke(struct iommufd_ucmd *ucmd, int fd, + bool revoked) +{ + struct iommufd_test_dma_buf *priv; + struct dma_buf *dmabuf; + int rc = 0; + + dmabuf = dma_buf_get(fd); + if (IS_ERR(dmabuf)) + return PTR_ERR(dmabuf); + + if (dmabuf->ops != &iommufd_test_dmabuf_ops) { + rc = -EOPNOTSUPP; + goto err_put; + } + + priv = dmabuf->priv; + dma_resv_lock(dmabuf->resv, NULL); + priv->revoked = revoked; + dma_buf_move_notify(dmabuf); + dma_resv_unlock(dmabuf->resv); + +err_put: + dma_buf_put(dmabuf); + return rc; +} + int iommufd_test(struct iommufd_ucmd *ucmd) { struct iommu_test_cmd *cmd = ucmd->cmd; @@ -2109,6 +2244,13 @@ int iommufd_test(struct iommufd_ucmd *ucmd) return iommufd_test_pasid_detach(ucmd, cmd); case IOMMU_TEST_OP_PASID_CHECK_HWPT: return iommufd_test_pasid_check_hwpt(ucmd, cmd); + case IOMMU_TEST_OP_DMABUF_GET: + return iommufd_test_dmabuf_get(ucmd, cmd->dmabuf_get.open_flags, + cmd->dmabuf_get.length); + case IOMMU_TEST_OP_DMABUF_REVOKE: + return iommufd_test_dmabuf_revoke(ucmd, + cmd->dmabuf_revoke.dmabuf_fd, + cmd->dmabuf_revoke.revoked); default: return -EOPNOTSUPP; } diff --git a/tools/testing/selftests/iommu/iommufd.c b/tools/testing/selftests/iommu/iommufd.c index 3eebf5e3b974f4..de348d6412791b 100644 --- a/tools/testing/selftests/iommu/iommufd.c +++ b/tools/testing/selftests/iommu/iommufd.c @@ -1574,6 +1574,49 @@ TEST_F(iommufd_ioas, copy_sweep) test_ioctl_destroy(dst_ioas_id); }
+TEST_F(iommufd_ioas, dmabuf_simple) +{ + size_t buf_size = PAGE_SIZE*4; + __u64 iova; + int dfd; + + test_cmd_get_dmabuf(buf_size, &dfd); + test_err_ioctl_ioas_map_file(EINVAL, dfd, 0, 0, &iova); + test_err_ioctl_ioas_map_file(EINVAL, dfd, buf_size, buf_size, &iova); + test_err_ioctl_ioas_map_file(EINVAL, dfd, 0, buf_size + 1, &iova); + test_ioctl_ioas_map_file(dfd, 0, buf_size, &iova); + + close(dfd); +} + +TEST_F(iommufd_ioas, dmabuf_revoke) +{ + size_t buf_size = PAGE_SIZE*4; + __u32 hwpt_id; + __u64 iova; + __u64 iova2; + int dfd; + + test_cmd_get_dmabuf(buf_size, &dfd); + test_ioctl_ioas_map_file(dfd, 0, buf_size, &iova); + test_cmd_revoke_dmabuf(dfd, true); + + if (variant->mock_domains) + test_cmd_hwpt_alloc(self->device_id, self->ioas_id, 0, + &hwpt_id); + + test_err_ioctl_ioas_map_file(ENODEV, dfd, 0, buf_size, &iova2); + + test_cmd_revoke_dmabuf(dfd, false); + test_ioctl_ioas_map_file(dfd, 0, buf_size, &iova2); + + /* Restore the iova back */ + test_ioctl_ioas_unmap(iova, buf_size); + test_ioctl_ioas_map_fixed_file(dfd, 0, buf_size, iova); + + close(dfd); +} + FIXTURE(iommufd_mock_domain) { int fd; diff --git a/tools/testing/selftests/iommu/iommufd_utils.h b/tools/testing/selftests/iommu/iommufd_utils.h index 772ca1db6e5971..f6d1678b310e1f 100644 --- a/tools/testing/selftests/iommu/iommufd_utils.h +++ b/tools/testing/selftests/iommu/iommufd_utils.h @@ -548,6 +548,39 @@ static int _test_cmd_destroy_access_pages(int fd, unsigned int access_id, EXPECT_ERRNO(_errno, _test_cmd_destroy_access_pages( \ self->fd, access_id, access_pages_id))
+static int _test_cmd_get_dmabuf(int fd, size_t len, int *out_fd) +{ + struct iommu_test_cmd cmd = { + .size = sizeof(cmd), + .op = IOMMU_TEST_OP_DMABUF_GET, + .dmabuf_get = { .length = len, .open_flags = O_CLOEXEC }, + }; + + *out_fd = ioctl(fd, IOMMU_TEST_CMD, &cmd); + if (*out_fd < 0) + return -1; + return 0; +} +#define test_cmd_get_dmabuf(len, out_fd) \ + ASSERT_EQ(0, _test_cmd_get_dmabuf(self->fd, len, out_fd)) + +static int _test_cmd_revoke_dmabuf(int fd, int dmabuf_fd, bool revoked) +{ + struct iommu_test_cmd cmd = { + .size = sizeof(cmd), + .op = IOMMU_TEST_OP_DMABUF_REVOKE, + .dmabuf_revoke = { .dmabuf_fd = dmabuf_fd, .revoked = revoked }, + }; + int ret; + + ret = ioctl(fd, IOMMU_TEST_CMD, &cmd); + if (ret < 0) + return -1; + return 0; +} +#define test_cmd_revoke_dmabuf(dmabuf_fd, revoke) \ + ASSERT_EQ(0, _test_cmd_revoke_dmabuf(self->fd, dmabuf_fd, revoke)) + static int _test_ioctl_destroy(int fd, unsigned int id) { struct iommu_destroy cmd = { @@ -718,6 +751,17 @@ static int _test_ioctl_ioas_map_file(int fd, unsigned int ioas_id, int mfd, self->fd, ioas_id, mfd, start, length, iova_p, \ IOMMU_IOAS_MAP_WRITEABLE | IOMMU_IOAS_MAP_READABLE))
+#define test_ioctl_ioas_map_fixed_file(mfd, start, length, iova) \ + ({ \ + __u64 __iova = iova; \ + ASSERT_EQ(0, _test_ioctl_ioas_map_file( \ + self->fd, self->ioas_id, mfd, start, \ + length, &__iova, \ + IOMMU_IOAS_MAP_FIXED_IOVA | \ + IOMMU_IOAS_MAP_WRITEABLE | \ + IOMMU_IOAS_MAP_READABLE)); \ + }) + static int _test_ioctl_set_temp_memory_limit(int fd, unsigned int limit) { struct iommu_test_cmd memlimit_cmd = {
On Mon, Oct 27, 2025 at 02:30:59PM -0300, Jason Gunthorpe wrote:
This series is the start of adding full DMABUF support to iommufd. Currently it is limited to only work with VFIO's DMABUF exporter. It sits on top of Leon's series to add a DMABUF exporter to VFIO:
https://lore.kernel.org/all/cover.1760368250.git.leon@kernel.org/
<...>
This is on github: https://github.com/jgunthorpe/linux/commits/iommufd_dmabuf
The branch has various modifications to Leon's series I've suggested.
I'm working on v6 these days.
Thanks
linaro-mm-sig@lists.linaro.org
-
Alex Mastro -
Jason Gunthorpe -
Leon Romanovsky