On Mon, 14 Jun 2021 at 12:54, Thomas Hellström
<thomas.hellstrom@xxxxxxxxxxxxxxx> wrote:
>
> After a TTM move or object init we need to update the i915 gem flags and
> caching settings to reflect the new placement. Currently caching settings
> are not changed during the lifetime of an object, although that might
> change moving forward if we run into performance issues or issues with
> WC system page allocations.
> Also introduce gpu_binds_iomem() and cpu_maps_iomem() to clean up the
> various ways we previously used to detect this.
> Finally, initialize the TTM object reserved to be able to update
> flags and caching before anyone else gets hold of the object.
>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> ---
> v2:
> - Style fixes (Reported by Matthew Auld)
> v3:
> - More style fixes. Clarify why we're updating caching settings after move.
> (Suggested by Matthew Auld)
> ---
> drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 111 +++++++++++++++++++-----
> 1 file changed, 89 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 33ab47f1e05b..5176682a7d19 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -70,6 +70,17 @@ static struct ttm_placement i915_sys_placement = {
> .busy_placement = &lmem0_sys_placement_flags[1],
> };
>
> +static bool gpu_binds_iomem(struct ttm_resource *mem)
> +{
> + return mem->mem_type != TTM_PL_SYSTEM;
> +}
> +
> +static bool cpu_maps_iomem(struct ttm_resource *mem)
> +{
> + /* Once / if we support GGTT, this is also false for cached ttm_tts */
> + return mem->mem_type != TTM_PL_SYSTEM;
> +}
> +
> static void i915_ttm_adjust_lru(struct drm_i915_gem_object *obj);
>
> static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
> @@ -175,6 +186,40 @@ static void i915_ttm_free_cached_io_st(struct drm_i915_gem_object *obj)
> obj->ttm.cached_io_st = NULL;
> }
>
> +static void
> +i915_ttm_adjust_domains_after_cpu_move(struct drm_i915_gem_object *obj)
> +{
> + struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
> +
> + if (cpu_maps_iomem(bo->resource) || bo->ttm->caching != ttm_cached) {
> + obj->write_domain = I915_GEM_DOMAIN_WC;
> + obj->read_domains = I915_GEM_DOMAIN_WC;
> + } else {
> + obj->write_domain = I915_GEM_DOMAIN_CPU;
> + obj->read_domains = I915_GEM_DOMAIN_CPU;
> + }
> +}
> +
> +static void i915_ttm_adjust_gem_after_move(struct drm_i915_gem_object *obj)
> +{
> + struct drm_i915_private *i915 = to_i915(obj->base.dev);
> + struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
> + unsigned int cache_level;
> +
> + obj->mem_flags &= ~(I915_BO_FLAG_STRUCT_PAGE | I915_BO_FLAG_IOMEM);
> +
> + obj->mem_flags |= cpu_maps_iomem(bo->resource) ? I915_BO_FLAG_IOMEM :
> + I915_BO_FLAG_STRUCT_PAGE;
> +
> + if ((HAS_LLC(i915) || HAS_SNOOP(i915)) && !gpu_binds_iomem(bo->resource) &&
> + bo->ttm->caching == ttm_cached)
> + cache_level = I915_CACHE_LLC;
> + else
> + cache_level = I915_CACHE_NONE;
> +
> + i915_gem_object_set_cache_coherency(obj, cache_level);
> +}
> +
> static void i915_ttm_purge(struct drm_i915_gem_object *obj)
> {
> struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
> @@ -190,8 +235,10 @@ static void i915_ttm_purge(struct drm_i915_gem_object *obj)
>
> /* TTM's purge interface. Note that we might be reentering. */
> ret = ttm_bo_validate(bo, &place, &ctx);
> -
> if (!ret) {
> + obj->write_domain = 0;
> + obj->read_domains = 0;
> + i915_ttm_adjust_gem_after_move(obj);
> i915_ttm_free_cached_io_st(obj);
> obj->mm.madv = __I915_MADV_PURGED;
> }
> @@ -273,12 +320,15 @@ i915_ttm_resource_get_st(struct drm_i915_gem_object *obj,
> struct ttm_resource *res)
> {
> struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
> - struct ttm_resource_manager *man =
> - ttm_manager_type(bo->bdev, res->mem_type);
>
> - if (man->use_tt)
> + if (!gpu_binds_iomem(res))
> return i915_ttm_tt_get_st(bo->ttm);
>
> + /*
> + * If CPU mapping differs, we need to add the ttm_tt pages to
> + * the resulting st. Might make sense for GGTT.
> + */
> + GEM_WARN_ON(!cpu_maps_iomem(res));
> return intel_region_ttm_node_to_st(obj->mm.region, res);
> }
>
> @@ -290,8 +340,6 @@ static int i915_ttm_move(struct ttm_buffer_object *bo, bool evict,
> struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
> struct ttm_resource_manager *dst_man =
> ttm_manager_type(bo->bdev, dst_mem->mem_type);
> - struct ttm_resource_manager *src_man =
> - ttm_manager_type(bo->bdev, bo->resource->mem_type);
> struct intel_memory_region *dst_reg, *src_reg;
> union {
> struct ttm_kmap_iter_tt tt;
> @@ -332,34 +380,36 @@ static int i915_ttm_move(struct ttm_buffer_object *bo, bool evict,
> if (IS_ERR(dst_st))
> return PTR_ERR(dst_st);
>
> - /* If we start mapping GGTT, we can no longer use man::use_tt here. */
> - dst_iter = dst_man->use_tt ?
> + dst_iter = !cpu_maps_iomem(dst_mem) ?
> ttm_kmap_iter_tt_init(&_dst_iter.tt, bo->ttm) :
> ttm_kmap_iter_iomap_init(&_dst_iter.io, &dst_reg->iomap,
> dst_st, dst_reg->region.start);
>
> - src_iter = src_man->use_tt ?
> + src_iter = !cpu_maps_iomem(bo->resource) ?
> ttm_kmap_iter_tt_init(&_src_iter.tt, bo->ttm) :
> ttm_kmap_iter_iomap_init(&_src_iter.io, &src_reg->iomap,
> obj->ttm.cached_io_st,
> src_reg->region.start);
>
> ttm_move_memcpy(bo, dst_mem->num_pages, dst_iter, src_iter);
> + /* Below dst_mem becomes bo->resource. */
> ttm_bo_move_sync_cleanup(bo, dst_mem);
> + i915_ttm_adjust_domains_after_cpu_move(obj);
> i915_ttm_free_cached_io_st(obj);
>
> - if (!dst_man->use_tt) {
> + if (gpu_binds_iomem(dst_mem) || cpu_maps_iomem(dst_mem)) {
> obj->ttm.cached_io_st = dst_st;
> obj->ttm.get_io_page.sg_pos = dst_st->sgl;
> obj->ttm.get_io_page.sg_idx = 0;
> }
>
> + i915_ttm_adjust_gem_after_move(obj);
> return 0;
> }
>
> static int i915_ttm_io_mem_reserve(struct ttm_device *bdev, struct ttm_resource *mem)
> {
> - if (mem->mem_type < I915_PL_LMEM0)
> + if (!cpu_maps_iomem(mem))
> return 0;
>
> mem->bus.caching = ttm_write_combined;
> @@ -421,6 +471,16 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
> if (ret)
> return ret == -ENOSPC ? -ENXIO : ret;
>
> + i915_ttm_adjust_lru(obj);
> + if (bo->ttm && !ttm_tt_is_populated(bo->ttm)) {
> + ret = ttm_tt_populate(bo->bdev, bo->ttm, &ctx);
> + if (ret)
> + return ret;
> +
> + i915_ttm_adjust_domains_after_cpu_move(obj);
> + i915_ttm_adjust_gem_after_move(obj);
> + }
> +
> /* Object either has a page vector or is an iomem object */
> st = bo->ttm ? i915_ttm_tt_get_st(bo->ttm) : obj->ttm.cached_io_st;
> if (IS_ERR(st))
> @@ -428,8 +488,6 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
>
> __i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl));
>
> - i915_ttm_adjust_lru(obj);
> -
> return ret;
> }
>
> @@ -563,6 +621,7 @@ static u64 i915_ttm_mmap_offset(struct drm_i915_gem_object *obj)
>
> const struct drm_i915_gem_object_ops i915_gem_ttm_obj_ops = {
> .name = "i915_gem_object_ttm",
> + .flags = I915_GEM_OBJECT_IS_SHRINKABLE,
>
> .get_pages = i915_ttm_get_pages,
> .put_pages = i915_ttm_put_pages,
> @@ -599,6 +658,10 @@ int __i915_gem_ttm_object_init(struct intel_memory_region *mem,
> {
> static struct lock_class_key lock_class;
> struct drm_i915_private *i915 = mem->i915;
> + struct ttm_operation_ctx ctx = {
> + .interruptible = true,
> + .no_wait_gpu = false,
> + };
> enum ttm_bo_type bo_type;
> size_t alignment = 0;
> int ret;
> @@ -618,15 +681,14 @@ int __i915_gem_ttm_object_init(struct intel_memory_region *mem,
> i915_gem_object_init(obj, &i915_gem_ttm_obj_ops, &lock_class, flags);
> i915_gem_object_init_memory_region(obj, mem);
> i915_gem_object_make_unshrinkable(obj);
> - obj->read_domains = I915_GEM_DOMAIN_WC | I915_GEM_DOMAIN_GTT;
> - obj->mem_flags |= I915_BO_FLAG_IOMEM;
> - i915_gem_object_set_cache_coherency(obj, I915_CACHE_NONE);
> INIT_RADIX_TREE(&obj->ttm.get_io_page.radix, GFP_KERNEL | __GFP_NOWARN);
> mutex_init(&obj->ttm.get_io_page.lock);
>
> bo_type = (obj->flags & I915_BO_ALLOC_USER) ? ttm_bo_type_device :
> ttm_bo_type_kernel;
>
> + obj->base.vma_node.driver_private = i915_gem_to_ttm(obj);
> +
> /*
> * If this function fails, it will call the destructor, but
> * our caller still owns the object. So no freeing in the
> @@ -634,14 +696,19 @@ int __i915_gem_ttm_object_init(struct intel_memory_region *mem,
> * Similarly, in delayed_destroy, we can't call ttm_bo_put()
> * until successful initialization.
> */
> - obj->base.vma_node.driver_private = i915_gem_to_ttm(obj);
> - ret = ttm_bo_init(&i915->bdev, i915_gem_to_ttm(obj), size,
> - bo_type, &i915_sys_placement, alignment,
> - true, NULL, NULL, i915_ttm_bo_destroy);
> + ret = ttm_bo_init_reserved(&i915->bdev, i915_gem_to_ttm(obj), size,
> + bo_type, &i915_sys_placement, alignment,
> + &ctx, NULL, NULL, i915_ttm_bo_destroy);
> +
> + if (ret)
> + goto out;
>
> - if (!ret)
> - obj->ttm.created = true;
> + obj->ttm.created = true;
> + i915_ttm_adjust_domains_after_cpu_move(obj);
> + i915_ttm_adjust_gem_after_move(obj);
> + i915_gem_object_unlock(obj);
Looks like the is_shrinkable change was squashed in the next patch.
Doesn't really matter,
Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
>
> +out:
> /* i915 wants -ENXIO when out of memory region space. */
> return (ret == -ENOSPC) ? -ENXIO : ret;
> }
> --
> 2.31.1
>
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