[PATCH 2/2] drm/amdgpu: Enable clear page functionality

Christian König christian.koenig at amd.com
Fri Dec 8 10:00:51 UTC 2023


Am 07.12.23 um 16:11 schrieb Arunpravin Paneer Selvam:
> Add clear page support in vram memory region.

The first patch looks good, but this here needs quite some work.

>
> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c    | 13 +++--
>   .../gpu/drm/amd/amdgpu/amdgpu_res_cursor.h    | 25 ++++++++++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       | 50 +++++++++++++++++++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h       |  4 ++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  | 14 +++++-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.h  |  5 ++
>   6 files changed, 105 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index cef920a93924..bc4ea87f8b5e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -39,6 +39,7 @@
>   #include "amdgpu.h"
>   #include "amdgpu_trace.h"
>   #include "amdgpu_amdkfd.h"
> +#include "amdgpu_vram_mgr.h"
>   
>   /**
>    * DOC: amdgpu_object
> @@ -629,15 +630,17 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
>   
>   	if (bp->flags & AMDGPU_GEM_CREATE_VRAM_CLEARED &&
>   	    bo->tbo.resource->mem_type == TTM_PL_VRAM) {
> -		struct dma_fence *fence;
> +		struct dma_fence *fence = NULL;
>   
> -		r = amdgpu_fill_buffer(bo, 0, bo->tbo.base.resv, &fence, true);
> +		r = amdgpu_clear_buffer(bo, bo->tbo.base.resv, &fence, true);
>   		if (unlikely(r))
>   			goto fail_unreserve;
>   
> -		dma_resv_add_fence(bo->tbo.base.resv, fence,
> -				   DMA_RESV_USAGE_KERNEL);
> -		dma_fence_put(fence);
> +		if (fence) {
> +			dma_resv_add_fence(bo->tbo.base.resv, fence,
> +					   DMA_RESV_USAGE_KERNEL);
> +			dma_fence_put(fence);
> +		}
>   	}
>   	if (!bp->resv)
>   		amdgpu_bo_unreserve(bo);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h
> index 381101d2bf05..50fcd86e1033 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h
> @@ -164,4 +164,29 @@ static inline void amdgpu_res_next(struct amdgpu_res_cursor *cur, uint64_t size)
>   	}
>   }
>   
> +/**
> + * amdgpu_res_cleared - check if blocks are cleared
> + *
> + * @cur: the cursor to extract the block
> + *
> + * Check if the @cur block is cleared
> + */
> +static inline bool amdgpu_res_cleared(struct amdgpu_res_cursor *cur)
> +{
> +	struct drm_buddy_block *block;
> +
> +	switch (cur->mem_type) {
> +	case TTM_PL_VRAM:
> +		block = cur->node;
> +
> +		if (!amdgpu_vram_mgr_is_cleared(block))
> +			return false;
> +		break;
> +	default:
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
>   #endif
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 05991c5c8ddb..6d7514e8f40c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -2222,6 +2222,56 @@ static int amdgpu_ttm_fill_mem(struct amdgpu_ring *ring, uint32_t src_data,
>   	return 0;
>   }
>   
> +int amdgpu_clear_buffer(struct amdgpu_bo *bo,
> +			struct dma_resv *resv,
> +			struct dma_fence **fence,
> +			bool delayed)

Drop the delayed parameter, that doesn't make any sense here.

And as Alex said please use an amdgpu_ttm_ prefix for the function name.

> +{
> +	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> +	struct amdgpu_ring *ring = adev->mman.buffer_funcs_ring;
> +	struct amdgpu_res_cursor cursor;
> +	struct dma_fence *f = NULL;
> +	u64 addr;
> +	int r;
> +
> +	if (!adev->mman.buffer_funcs_enabled)
> +		return -EINVAL;
> +
> +	amdgpu_res_first(bo->tbo.resource, 0, amdgpu_bo_size(bo), &cursor);
> +
> +	mutex_lock(&adev->mman.gtt_window_lock);
> +	while (cursor.remaining) {
> +		struct dma_fence *next = NULL;
> +		u64 size;
> +
> +		/* Never clear more than 256MiB at once to avoid timeouts */
> +		size = min(cursor.size, 256ULL << 20);
> +
> +		if (!amdgpu_res_cleared(&cursor)) {

This needs to come before the min(cursor.size....) directly above. I 
suggest a handling like this:

if (amdgpu_res_cleared(&cursor)) {
	amdgpu_res_next(&cursor, cursor.size);
	continue;
}

size = min(....

> +			r = amdgpu_ttm_map_buffer(&bo->tbo, bo->tbo.resource, &cursor,
> +						  1, ring, false, &size, &addr);
> +			if (r)
> +				goto err;
> +
> +			r = amdgpu_ttm_fill_mem(ring, 0, addr, size, resv,
> +						&next, true, delayed);
> +			if (r)
> +				goto err;
> +		}
> +		dma_fence_put(f);
> +		f = next;
> +
> +		amdgpu_res_next(&cursor, size);
> +	}
> +err:
> +	mutex_unlock(&adev->mman.gtt_window_lock);
> +	if (fence)
> +		*fence = dma_fence_get(f);
> +	dma_fence_put(f);
> +
> +	return r;
> +}
> +
>   int amdgpu_fill_buffer(struct amdgpu_bo *bo,
>   			uint32_t src_data,
>   			struct dma_resv *resv,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index 65ec82141a8e..838251166883 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -155,6 +155,10 @@ int amdgpu_ttm_copy_mem_to_mem(struct amdgpu_device *adev,
>   			       uint64_t size, bool tmz,
>   			       struct dma_resv *resv,
>   			       struct dma_fence **f);
> +int amdgpu_clear_buffer(struct amdgpu_bo *bo,
> +			struct dma_resv *resv,
> +			struct dma_fence **fence,
> +			bool delayed);
>   int amdgpu_fill_buffer(struct amdgpu_bo *bo,
>   			uint32_t src_data,
>   			struct dma_resv *resv,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index d0e199cc8f17..ff74c324b5b5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -435,6 +435,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   {
>   	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
>   	struct amdgpu_device *adev = to_amdgpu_device(mgr);
> +	struct amdgpu_bo *bo = ttm_to_amdgpu_bo(tbo);
>   	u64 vis_usage = 0, max_bytes, min_block_size;
>   	struct amdgpu_vram_mgr_resource *vres;
>   	u64 size, remaining_size, lpfn, fpfn;
> @@ -486,6 +487,9 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   	if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
>   		vres->flags |= DRM_BUDDY_CONTIGUOUS_ALLOCATION;
>   
> +	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CLEARED)
> +		vres->flags |= DRM_BUDDY_CLEAR_ALLOCATION;
> +
>   	if (fpfn || lpfn != mgr->mm.size)
>   		/* Allocate blocks in desired range */
>   		vres->flags |= DRM_BUDDY_RANGE_ALLOCATION;
> @@ -579,7 +583,9 @@ static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
>   	struct amdgpu_vram_mgr_resource *vres = to_amdgpu_vram_mgr_resource(res);
>   	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
>   	struct amdgpu_device *adev = to_amdgpu_device(mgr);
> +	struct amdgpu_bo *bo = ttm_to_amdgpu_bo(res->bo);
>   	struct drm_buddy *mm = &mgr->mm;
> +	struct dma_fence *fence = NULL;
>   	struct drm_buddy_block *block;
>   	uint64_t vis_usage = 0;
>   
> @@ -589,7 +595,13 @@ static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
>   
>   	amdgpu_vram_mgr_do_reserve(man);
>   
> -	drm_buddy_free_list(mm, &vres->blocks, 0);
> +	/* Clear all the blocks in free path */
> +	if (!amdgpu_fill_buffer(bo, 0, NULL, &fence, true)) {
> +		vres->flags |= DRM_BUDDY_CLEARED;
> +		dma_fence_put(fence);
> +	}
> +

That's a pretty clear no-go. This is the backend and CS is done from the 
front end. E.g. can't properly wait for the fence for example.

Instead use the AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE flag for this.

IIRC we already always set this flag when ras is enabled, just make it 
mandatory for now.

> +	drm_buddy_free_list(mm, &vres->blocks, vres->flags);
>   	mutex_unlock(&mgr->lock);
>   
>   	atomic64_sub(vis_usage, &mgr->vis_usage);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.h
> index 0e04e42cf809..8478522d7366 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.h
> @@ -53,6 +53,11 @@ static inline u64 amdgpu_vram_mgr_block_size(struct drm_buddy_block *block)
>   	return (u64)PAGE_SIZE << drm_buddy_block_order(block);
>   }
>   
> +static inline bool amdgpu_vram_mgr_is_cleared(struct drm_buddy_block *block)
> +{
> +	return drm_buddy_block_is_clear(block);
> +}
> +

You also need a functionality which resets all cleared blocks to 
uncleared after suspend/resume.

No idea how to do this, maybe Alex knows of hand.

Regards,
Christian.

>   static inline struct amdgpu_vram_mgr_resource *
>   to_amdgpu_vram_mgr_resource(struct ttm_resource *res)
>   {



More information about the amd-gfx mailing list