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    SubjectRe: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT_INVALIDATE
    From
    On 2023/11/20 16:09, Tian, Kevin wrote:
    >> From: Liu, Yi L <yi.l.liu@intel.com>
    >> Sent: Friday, November 17, 2023 9:07 PM
    >> +
    >> + hwpt = iommufd_hw_pagetable_get_nested(ucmd, cmd->hwpt_id);
    >> + if (IS_ERR(hwpt))
    >> + return PTR_ERR(hwpt);
    >> +
    >> + rc = hwpt->domain->ops->cache_invalidate_user(hwpt->domain,
    >> &data_array,
    >> + &cmd-
    >>> out_driver_error_code);
    >> + cmd->req_num = data_array.entry_num;
    >> + if (iommufd_ucmd_respond(ucmd, sizeof(*cmd)))
    >> + return -EFAULT;
    >> + iommufd_put_object(&hwpt->obj);
    >
    > the object is not put when ucmd response fails. It can be put right
    > after calling @cache_invalidate_user()

    yes.

    >> @@ -309,6 +309,7 @@ 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;
    >
    > In alphabetic order this should be put before "hwpt_set_dirty"

    yes.

    >> struct iommu_ioas_alloc alloc;
    >> struct iommu_ioas_allow_iovas allow_iovas;
    >> struct iommu_ioas_copy ioas_copy;
    >> @@ -348,6 +349,8 @@ static const struct iommufd_ioctl_op
    >> iommufd_ioctl_ops[] = {
    >> struct iommu_hwpt_get_dirty_bitmap, data),
    >> IOCTL_OP(IOMMU_HWPT_SET_DIRTY_TRACKING,
    >> iommufd_hwpt_set_dirty_tracking,
    >> struct iommu_hwpt_set_dirty_tracking, __reserved),
    >> + IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,
    >> + struct iommu_hwpt_invalidate, out_driver_error_code),
    >
    > ditto
    >
    >> +/**
    >> + * 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
    >
    > remove the first 'HWPT'

    >> + * @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.
    >> + * @req_type: One of enum iommu_hwpt_data_type, defining the data
    >> type of all
    >> + * the entries in the invalidation request array. It should suit
    >> + * with the data_type passed per the allocation of the hwpt pointed
    >> + * by @hwpt_id.
    >
    > "It should match the data_type given to the specified hwpt"

    above comments are well received. :)

    >> + * @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.
    >> + * @out_driver_error_code: Report a driver speicifc error code upon failure.
    >> + * It's optional, driver has a choice to fill it or
    >> + * not.
    >
    > Being optional how does the user tell whether the code is filled or not?

    seems like we need a flag for it. otherwise, a reserved special value is
    required. or is it enough to just document it that this field is available
    or not per the iommu_hw_info_type?

    >> + *
    >> + * 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.
    >> + */
    >> +struct iommu_hwpt_invalidate {
    >> + __u32 size;
    >> + __u32 hwpt_id;
    >> + __aligned_u64 reqs_uptr;
    >> + __u32 req_type;
    >> + __u32 req_len;
    >> + __u32 req_num;
    >> + __u32 out_driver_error_code;
    >> +};
    >
    > Probably 'data_uptr', 'data_type', "entry_len' and 'entry_num" read slightly
    > better.

    sure.

    --
    Regards,
    Yi Liu

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