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iommufd/viommu: Add driver-defined vDEVICE support

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NVIDIA VCMDQ driver will have a driver-defined vDEVICE structure and do
some HW configurations with that.

To allow IOMMU drivers to define their own vDEVICE structures, move the
struct iommufd_vdevice to the public header and provide a pair of viommu
ops, similar to get_viommu_size and viommu_init.

Doing this, however, creates a new window between the vDEVICE allocation
and its driver-level initialization, during which an abort could happen
but it can't invoke a driver destroy function from the struct viommu_ops
since the driver structure isn't initialized yet. vIOMMU object doesn't
have this problem, since its destroy op is set via the viommu_ops by the
driver viommu_init function. Thus, vDEVICE should do something similar:
add a destroy function pointer inside the struct iommufd_vdevice instead
of the struct iommufd_viommu_ops.

Note that there is unlikely a use case for a type dependent vDEVICE, so
a static vdevice_size is probably enough for the near term instead of a
get_vdevice_size function op.

Link: https://patch.msgid.link/r/1e751c01da7863c669314d8e27fdb89eabcf5605.1752126748.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Nicolin Chen 2025-07-09 22:59:04 -07:00 committed by Jason Gunthorpe
parent 27b77ea5fe
commit ed42eee797
3 changed files with 56 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/iommu/iommufd/iommufd_private.h
View File

@ -653,18 +653,6 @@ void iommufd_viommu_destroy(struct iommufd_object *obj);
int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd);
void iommufd_vdevice_destroy(struct iommufd_object *obj);
struct iommufd_vdevice {
struct iommufd_object obj;
struct iommufd_viommu *viommu;
struct device *dev;
/*
* Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID of
* AMD IOMMU, and vRID of Intel VT-d
*/
u64 virt_id;
};
#ifdef CONFIG_IOMMUFD_TEST
int iommufd_test(struct iommufd_ucmd *ucmd);
void iommufd_selftest_destroy(struct iommufd_object *obj);

26
drivers/iommu/iommufd/viommu.c
View File

@ -116,6 +116,8 @@ void iommufd_vdevice_destroy(struct iommufd_object *obj)
container_of(obj, struct iommufd_vdevice, obj);
struct iommufd_viommu *viommu = vdev->viommu;
if (vdev->destroy)
vdev->destroy(vdev);
/* xa_cmpxchg is okay to fail if alloc failed xa_cmpxchg previously */
xa_cmpxchg(&viommu->vdevs, vdev->virt_id, vdev, NULL, GFP_KERNEL);
refcount_dec(&viommu->obj.users);
@ -126,6 +128,7 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
{
struct iommu_vdevice_alloc *cmd = ucmd->cmd;
struct iommufd_vdevice *vdev, *curr;
size_t vdev_size = sizeof(*vdev);
struct iommufd_viommu *viommu;
struct iommufd_device *idev;
u64 virt_id = cmd->virt_id;
@ -150,7 +153,22 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
goto out_put_idev;
}
vdev = iommufd_object_alloc_ucmd(ucmd, vdev, IOMMUFD_OBJ_VDEVICE);
if (viommu->ops && viommu->ops->vdevice_size) {
/*
* It is a driver bug for:
* - ops->vdevice_size smaller than the core structure size
* - not implementing a pairing ops->vdevice_init op
*/
if (WARN_ON_ONCE(viommu->ops->vdevice_size < vdev_size ||
!viommu->ops->vdevice_init)) {
rc = -EOPNOTSUPP;
goto out_put_idev;
}
vdev_size = viommu->ops->vdevice_size;
}
vdev = (struct iommufd_vdevice *)_iommufd_object_alloc_ucmd(
ucmd, vdev_size, IOMMUFD_OBJ_VDEVICE);
if (IS_ERR(vdev)) {
rc = PTR_ERR(vdev);
goto out_put_idev;
@ -168,6 +186,12 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
goto out_put_idev;
}
if (viommu->ops && viommu->ops->vdevice_init) {
rc = viommu->ops->vdevice_init(vdev);
if (rc)
goto out_put_idev;
}
cmd->out_vdevice_id = vdev->obj.id;
rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));

31
include/linux/iommufd.h
View File

@ -104,6 +104,21 @@ struct iommufd_viommu {
enum iommu_viommu_type type;
};
struct iommufd_vdevice {
struct iommufd_object obj;
struct iommufd_viommu *viommu;
struct device *dev;
/*
* Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID of
* AMD IOMMU, and vRID of Intel VT-d
*/
u64 virt_id;
/* Clean up all driver-specific parts of an iommufd_vdevice */
void (*destroy)(struct iommufd_vdevice *vdev);
};
/**
* struct iommufd_viommu_ops - vIOMMU specific operations
* @destroy: Clean up all driver-specific parts of an iommufd_viommu. The memory
@ -120,6 +135,14 @@ struct iommufd_viommu {
* array->entry_num to report the number of handled requests.
* The data structure of the array entry must be defined in
* include/uapi/linux/iommufd.h
* @vdevice_size: Size of the driver-defined vDEVICE structure per this vIOMMU
* @vdevice_init: Initialize the driver-level structure of a vDEVICE object, or
* related HW procedure. @vdev is already initialized by iommufd
* core: vdev->dev and vdev->viommu pointers; vdev->id carries a
* per-vIOMMU virtual ID (refer to struct iommu_vdevice_alloc in
* include/uapi/linux/iommufd.h)
* If driver has a deinit function to revert what vdevice_init op
* does, it should set it to the @vdev->destroy function pointer
*/
struct iommufd_viommu_ops {
void (*destroy)(struct iommufd_viommu *viommu);
@ -128,6 +151,8 @@ struct iommufd_viommu_ops {
const struct iommu_user_data *user_data);
int (*cache_invalidate)(struct iommufd_viommu *viommu,
struct iommu_user_data_array *array);
const size_t vdevice_size;
int (*vdevice_init)(struct iommufd_vdevice *vdev);
};
#if IS_ENABLED(CONFIG_IOMMUFD)
@ -224,4 +249,10 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) + \
BUILD_BUG_ON_ZERO(!__same_type(struct iommufd_viommu, \
((drv_struct *)NULL)->member)))
#define VDEVICE_STRUCT_SIZE(drv_struct, member) \
(sizeof(drv_struct) + \
BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) + \
BUILD_BUG_ON_ZERO(!__same_type(struct iommufd_vdevice, \
((drv_struct *)NULL)->member)))
#endif