Acked-by: Jordan Justen <jordan.l.justen@xxxxxxxxx>
On 2022-10-04 04:49:15, Matthew Auld wrote:
> On some platforms we potentially have different alignment restrictions
> depending on the memory type. We also now have different alignment
> restrictions for the same region across different kernel versions.
> Extend the region query to return the minimum required GTT alignment.
>
> Testcase: igt@gem_create@create-ext-placement-alignment
> Testcase: igt@i915_query@query-regions-sanity-check
> Suggested-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Michal Mrozek <michal.mrozek@xxxxxxxxx>
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> Cc: Stuart Summers <stuart.summers@xxxxxxxxx>
> Cc: Jordan Justen <jordan.l.justen@xxxxxxxxx>
> Cc: Yang A Shi <yang.a.shi@xxxxxxxxx>
> Cc: Nirmoy Das <nirmoy.das@xxxxxxxxx>
> Cc: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_query.c | 1 +
> include/uapi/drm/i915_drm.h | 29 +++++++++++++++++++++++++++--
> 2 files changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_query.c b/drivers/gpu/drm/i915/i915_query.c
> index 6ec9c9fb7b0d..111377f210ed 100644
> --- a/drivers/gpu/drm/i915/i915_query.c
> +++ b/drivers/gpu/drm/i915/i915_query.c
> @@ -498,6 +498,7 @@ static int query_memregion_info(struct drm_i915_private *i915,
> info.region.memory_class = mr->type;
> info.region.memory_instance = mr->instance;
> info.probed_size = mr->total;
> + info.gtt_alignment = mr->min_page_size;
>
> if (mr->type == INTEL_MEMORY_LOCAL)
> info.probed_cpu_visible_size = mr->io_size;
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 08d69e36fb66..2e613109356b 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -3346,8 +3346,33 @@ struct drm_i915_memory_region_info {
> /** @region: The class:instance pair encoding */
> struct drm_i915_gem_memory_class_instance region;
>
> - /** @rsvd0: MBZ */
> - __u32 rsvd0;
> + union {
> + /** @rsvd0: MBZ */
> + __u32 rsvd0;
> + /**
> + * @gtt_alignment:
> + *
> + * The minimum required GTT alignment for this type of memory.
> + * When allocating a GTT address it must be aligned to this
> + * value or larger. On some platforms the kernel might opt to
> + * using 64K pages for I915_MEMORY_CLASS_DEVICE, where 64K GTT
> + * pages can then be used if we also use 64K GTT alignment.
> + *
> + * NOTE: If this is zero then this must be an older
> + * kernel which lacks support for this field.
> + *
> + * Side note: For larger objects (especially for
> + * I915_MEMORY_CLASS_DEVICE), like 2M+ in size, userspace should
> + * consider potentially bumping the GTT alignment to say 2M,
> + * which could potentially increase the likelihood of the kernel
> + * being able to utilise 2M GTT pages underneath, if the layout
> + * of the physical pages allows it. On some configurations we
> + * can then also use a more efficient page-table layout, if we
> + * can't use the more desirable 2M GTT page, so long as we know
> + * that the entire page-table will be used by this object.
> + */
> + __u32 gtt_alignment;
> + };
>
> /**
> * @probed_size: Memory probed by the driver
> --
> 2.37.3
>
