RE: [PATCH v7 2/9] iommufd: Add IOMMU_HWPT_INVALIDATE

Tian, Kevin
2023-12-22T03:19:25Z

> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Thursday, December 21, 2023 11:40 PM
> +
> +int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd)
> +{
> + struct iommu_hwpt_invalidate *cmd = ucmd->cmd;
> + struct iommu_user_data_array data_array = {
> + .type = cmd->req_type,
> + .uptr = u64_to_user_ptr(cmd->reqs_uptr),
> + .entry_len = cmd->req_len,
> + .entry_num = cmd->req_num,
> + };
> + struct iommufd_hw_pagetable *hwpt;
> + u32 done_num = 0;
> + int rc;
> +
> + if (cmd->req_num && (!cmd->reqs_uptr || !cmd->req_len)) {
> + rc = -EINVAL;
> + goto out;
> + }

miss a check on the __reserved field.

> @@ -323,6 +323,7 @@ union ucmd_buffer {
> struct iommu_hwpt_alloc hwpt;
> struct iommu_hwpt_get_dirty_bitmap get_dirty_bitmap;
> struct iommu_hwpt_set_dirty_tracking set_dirty_tracking;
> + struct iommu_hwpt_invalidate cache;

this should be in alphabetic order. I gave this comment in v6 too:

https://lore.kernel.org/linux-iommu/BN9PR11MB5276D8406BF08B853329288C8CB4A@BN9PR11MB5276.namprd11.prod.outlook.com/

> +/**
> + * enum iommu_hwpt_invalidate_data_type - IOMMU HWPT Cache
> Invalidation
> + * Data Type
> + * @IOMMU_HWPT_INVALIDATE_DATA_VTD_S1: Invalidation data for
> VTD_S1
> + */
> +enum iommu_hwpt_invalidate_data_type {
> + IOMMU_HWPT_INVALIDATE_DATA_VTD_S1,
> +};

Defining DATA_VTD_S1 at this point is fine, if there is no usage on
DATA_NONE. But following vtd specific definitions should be moved
to the later vtd specific patches. they are not used by the common
code anyway.

> +
> +/**
> + * enum iommu_hwpt_vtd_s1_invalidate_flags - Flags for Intel VT-d
> + * stage-1 cache invalidation
> + * @IOMMU_VTD_INV_FLAGS_LEAF: The LEAF flag indicates whether only
> the
> + * leaf PTE caching needs to be invalidated
> + * and other paging structure caches can be
> + * preserved.

"indicates whether the invalidation applies to all-levels page structure
cache or just the leaf PTE cache"

> + */
> +enum iommu_hwpt_vtd_s1_invalidate_flags {
> + IOMMU_VTD_INV_FLAGS_LEAF = 1 << 0,
> +};
> +
> +/**
> + * enum iommu_hwpt_vtd_s1_invalidate_error - Result of invalidation

"hardware error of invalidation"

> + * @IOMMU_HWPT_INVALIDATE_VTD_S1_ICE: Invalidation Completion
> Error, details
> + * refer to 11.4.7.1 Fault Status Register
> + * of VT-d specification.
> + * @IOMMU_HWPT_INVALIDATE_VTD_S1_ITE: Invalidation Time-out Error,
> details
> + * refer to 11.4.7.1 Fault Status Register
> + * of VT-d specification.
> + */
> +enum iommu_hwpt_vtd_s1_invalidate_error {
> + IOMMU_HWPT_INVALIDATE_VTD_S1_ICE = 1 << 0,
> + IOMMU_HWPT_INVALIDATE_VTD_S1_ITE = 1 << 1,
> +};
> +
> +/**
> + * struct iommu_hwpt_vtd_s1_invalidate - Intel VT-d cache invalidation
> + * (IOMMU_HWPT_INVALIDATE_DATA_VTD_S1)
> + * @addr: The start address of the addresses to be invalidated. It needs
> + * to be 4KB aligned.

'of the range'

> + * @npages: Number of contiguous 4K pages to be invalidated.
> + * @flags: Combination of enum iommu_hwpt_vtd_s1_invalidate_flags
> + * @inv_error: One of enum iommu_hwpt_vtd_s1_invalidate_error

'@hw_error'

> + *
> + * The Intel VT-d specific invalidation data for user-managed stage-1 cache
> + * invalidation in nested translation. Userspace uses this structure to
> + * tell the impacted cache scope after modifying the stage-1 page table.
> + *
> + * Invalidating all the caches related to the page table by setting @addr
> + * to be 0 and @npages to be U64_MAX.

here should clarify that the invalidation applies to device TLB automatically
for VT-d.

> + *
> + * @inv_error is meaningful only if the request is handled by kernel. This
> + * can be known by checking struct iommu_hwpt_invalidate::req_num
> output.
> + * @inv_error only covers the errors detected by hardware after submitting
> the
> + * invalidation. The software detected errors would go through the normal
> + * ioctl errno.
> + */
> +struct iommu_hwpt_vtd_s1_invalidate {
> + __aligned_u64 addr;
> + __aligned_u64 npages;
> + __u32 flags;
> + __u32 inv_error;
> +};
> +
> +/**
> + * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
> + * @size: sizeof(struct iommu_hwpt_invalidate)
> + * @hwpt_id: HWPT ID of a nested HWPT for cache invalidation
> + * @reqs_uptr: User pointer to an array having @req_num of cache
> invalidation
> + * requests. The request entries in the array are of fixed width
> + * @req_len, and contain a user data structure for invalidation
> + * request specific to the given hardware page table.

Just:

'User pointer to an array of driver-specific cache invalidation requests'

> + * @req_type: One of enum iommu_hwpt_invalidate_data_type, defining
> the data
> + * type of all the entries in the invalidation request array. It
> + * should be a type supported by the hwpt pointed by @hwpt_id.
> + * @req_len: Length (in bytes) of a request entry in the request array
> + * @req_num: Input the number of cache invalidation requests in the array.
> + * Output the number of requests successfully handled by kernel.
> + * @__reserved: Must be 0.
> + *
> + * Invalidate the iommu cache for user-managed page table. Modifications
> on a
> + * user-managed page table should be followed by this operation to sync
> cache.
> + * Each ioctl can support one or more cache invalidation requests in the
> array
> + * that has a total size of @req_len * @req_num.
> + *
> + * An empty invalidation request array by setting @req_num==0 is allowed,
> and
> + * @req_len and @reqs_uptr would be ignored in this case. This can be
> used to
> + * check if the given @req_type is supported or not by kernel.
> + */
> +struct iommu_hwpt_invalidate {
> + __u32 size;
> + __u32 hwpt_id;
> + __aligned_u64 reqs_uptr;
> + __u32 req_type;
> + __u32 req_len;
> + __u32 req_num;
> + __u32 __reserved;
> +};
> +#define IOMMU_HWPT_INVALIDATE _IO(IOMMUFD_TYPE,
> IOMMUFD_CMD_HWPT_INVALIDATE)
> #endif
> --
> 2.34.1