On Thu, 10 Oct 2024 at 00:40, Nicolin Chen nicolinc@nvidia.com wrote:
Add a new IOMMUFD_OBJ_VIOMMU with an iommufd_viommu structure to represent a slice of physical IOMMU device passed to or shared with a user space VM. This slice, now a vIOMMU object, is a group of virtualization resources of a physical IOMMU's, such as:
- Security namespace for guest owned ID, e.g. guest-controlled cache tags
- Access to a sharable nesting parent pagetable across physical IOMMUs
- Virtualization of various platforms IDs, e.g. RIDs and others
- Delivery of paravirtualized invalidation
- Direct assigned invalidation queues
- Direct assigned interrupts
- Non-affiliated event reporting
Add a new viommu_alloc op in iommu_ops, for drivers to allocate their own vIOMMU structures. And this allocation also needs a free(), so add struct iommufd_viommu_ops.
To simplify a vIOMMU allocation, provide a iommufd_viommu_alloc() helper. It's suggested that a driver should embed a core-level viommu structure in its driver-level viommu struct and call the iommufd_viommu_alloc() helper, meanwhile the driver can also implement a viommu ops: struct my_driver_viommu { struct iommufd_viommu core; /* driver-owned properties/features */ .... };
static const struct iommufd_viommu_ops my_driver_viommu_ops = { .free = my_driver_viommu_free, /* future ops for virtualization features */ .... }; static struct iommufd_viommu my_driver_viommu_alloc(...) { struct my_driver_viommu *my_viommu = iommufd_viommu_alloc(ictx, my_driver_viommu, core, my_driver_viommu_ops); /* Init my_viommu and related HW feature */ .... return &my_viommu->core; } static struct iommu_domain_ops my_driver_domain_ops = { .... .viommu_alloc = my_driver_viommu_alloc, };To make the Kernel config work between a driver and the iommufd core, put the for-driver allocation helpers into a new viommu_api file building with CONFIG_IOMMUFD_DRIVER.
Signed-off-by: Nicolin Chen nicolinc@nvidia.com
diff --git a/drivers/iommu/iommufd/viommu_api.c b/drivers/iommu/iommufd/viommu_api.c new file mode 100644 index 000000000000..c1731f080d6b --- /dev/null +++ b/drivers/iommu/iommufd/viommu_api.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2024, NVIDIA CORPORATION & AFFILIATES
- */
+#include "iommufd_private.h"
+struct iommufd_object *iommufd_object_alloc_elm(struct iommufd_ctx *ictx,
size_t size,enum iommufd_object_type type)+{
struct iommufd_object *obj;int rc;obj = kzalloc(size, GFP_KERNEL_ACCOUNT);if (!obj)return ERR_PTR(-ENOMEM);obj->type = type;/* Starts out bias'd by 1 until it is removed from the xarray */refcount_set(&obj->shortterm_users, 1);refcount_set(&obj->users, 1);
here set refcont 1
iommufd_device_bind -> iommufd_object_alloc(ictx, idev, IOMMUFD_OBJ_DEVICE): refcont -> 1 refcount_inc(&idev->obj.users); refcount -> 2 will cause iommufd_device_unbind fail.
May remove refcount_inc(&idev->obj.users) in iommufd_device_bind
Thanks