Re: [PATCH v2 01/12] drm/xe: Add normalize_invalidation_range

["Summers, Stuart" <stuart.summers@intel.com>]

On Tue, 2025-11-04 at 11:56 -0800, Matthew Brost wrote:
> Extract the code that determines the alignment of TLB invalidation
> into
> a helper function — normalize_invalidation_range. This will be useful
> when adding context-based invalidations to the GuC TLB invalidation
> backend.
> 
> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Stuart Summers <stuart.summers@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_guc_tlb_inval.c | 71 +++++++++++++------------
> --
>  1 file changed, 35 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
> b/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
> index a80175c7c478..61bfa0d485f6 100644
> --- a/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
> +++ b/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
> @@ -92,6 +92,38 @@ static int send_tlb_inval_ggtt(struct xe_tlb_inval
> *tlb_inval, u32 seqno)
>         return -ECANCELED;
>  }
>  
> +static u64 normalize_invalidation_range(struct xe_gt *gt, u64
> *start, u64 *end)
> +{
> +       u64 orig_start = *start;
> +       u64 length = *end - *start;
> +       u64 align;
> +
> +       if (length < SZ_4K)
> +               length = SZ_4K;
> +
> +       align = roundup_pow_of_two(length);
> +       *start = ALIGN_DOWN(*start, align);
> +       *end = ALIGN(*end, align);
> +       length = align;
> +       while (*start + length < *end) {
> +               length <<= 1;
> +               *start = ALIGN_DOWN(orig_start, length);
> +       }
> +
> +       if (length >= SZ_2M) {
> +               length = max_t(u64, SZ_16M, length);
> +               *start = ALIGN_DOWN(orig_start, length);
> +       }
> +
> +       xe_gt_assert(gt, length >= SZ_4K);
> +       xe_gt_assert(gt, is_power_of_2(length));
> +       xe_gt_assert(gt, !(length & GENMASK(ilog2(SZ_16M) - 1,
> +                                           ilog2(SZ_2M) + 1)));
> +       xe_gt_assert(gt, IS_ALIGNED(*start, length));
> +
> +       return length;
> +}
> +
>  /*
>   * Ensure that roundup_pow_of_two(length) doesn't overflow.
>   * Note that roundup_pow_of_two() operates on unsigned long,
> @@ -118,47 +150,14 @@ static int send_tlb_inval_ppgtt(struct
> xe_tlb_inval *tlb_inval, u32 seqno,
>             length > MAX_RANGE_TLB_INVALIDATION_LENGTH) {
>                 action[len++] = MAKE_INVAL_OP(XE_GUC_TLB_INVAL_FULL);
>         } else {
> -               u64 orig_start = start;
> -               u64 align;
> -
> -               if (length < SZ_4K)
> -                       length = SZ_4K;
> -
> -               /*
> -                * We need to invalidate a higher granularity if
> start address
> -                * is not aligned to length. When start is not
> aligned with
> -                * length we need to find the length large enough to
> create an
> -                * address mask covering the required range.
> -                */
> -               align = roundup_pow_of_two(length);
> -               start = ALIGN_DOWN(start, align);
> -               end = ALIGN(end, align);
> -               length = align;
> -               while (start + length < end) {
> -                       length <<= 1;
> -                       start = ALIGN_DOWN(orig_start, length);
> -               }
> -
> -               /*
> -                * Minimum invalidation size for a 2MB page that the
> hardware
> -                * expects is 16MB
> -                */
> -               if (length >= SZ_2M) {
> -                       length = max_t(u64, SZ_16M, length);
> -                       start = ALIGN_DOWN(orig_start, length);
> -               }
> -
> -               xe_gt_assert(gt, length >= SZ_4K);
> -               xe_gt_assert(gt, is_power_of_2(length));
> -               xe_gt_assert(gt, !(length & GENMASK(ilog2(SZ_16M) -
> 1,
> -                                                   ilog2(SZ_2M) +
> 1)));
> -               xe_gt_assert(gt, IS_ALIGNED(start, length));
> +               u64 normalize_len = normalize_invalidation_range(gt,
> &start,
> +                                                               
> &end);
>  
>                 action[len++] =
> MAKE_INVAL_OP(XE_GUC_TLB_INVAL_PAGE_SELECTIVE);
>                 action[len++] = asid;
>                 action[len++] = lower_32_bits(start);
>                 action[len++] = upper_32_bits(start);
> -               action[len++] = ilog2(length) - ilog2(SZ_4K);
> +               action[len++] = ilog2(normalize_len) - ilog2(SZ_4K);
>         }
>  
>         xe_gt_assert(gt, len <= MAX_TLB_INVALIDATION_LEN);