Re: [PATCH v2] drm/amdgpu: Protect the validate list with a mutex

["Christian König" <christian.koenig@amd.com>]

The mutex must be added to the bo_list structure, not the parser structure.

The parser is only a temporary structure we allocate for the current thread.

Regards,
Christian.

Am 23.06.22 um 06:39 schrieb Luben Tuikov:
> Protect the parser's validate list with a mutex in order to avoid buffer
> object corruption as recorded in the link below.
>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Alex Deucher <Alexander.Deucher@amd.com>
> Cc: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
> Cc: Vitaly Prosyak <Vitaly.Prosyak@amd.com>
> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2048
> Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 30 ++++++++++++++++++++------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h |  4 ++++
>   2 files changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 36ac1f1d11e6b4..0be0bf17c05420 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -498,6 +498,7 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>   	struct amdgpu_bo *oa;
>   	int r;
>   
> +	mutex_init(&p->mutex_validated);
>   	INIT_LIST_HEAD(&p->validated);
>   
>   	/* p->bo_list could already be assigned if AMDGPU_CHUNK_ID_BO_HANDLES is present */
> @@ -521,13 +522,15 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>   	amdgpu_bo_list_for_each_entry(e, p->bo_list)
>   		e->tv.num_shared = 2;
>   
> -	amdgpu_bo_list_get_list(p->bo_list, &p->validated);
> -
>   	INIT_LIST_HEAD(&duplicates);
> +
> +	mutex_lock(&p->mutex_validated);
> +	amdgpu_bo_list_get_list(p->bo_list, &p->validated);
>   	amdgpu_vm_get_pd_bo(&fpriv->vm, &p->validated, &p->vm_pd);
>   
>   	if (p->uf_entry.tv.bo && !ttm_to_amdgpu_bo(p->uf_entry.tv.bo)->parent)
>   		list_add(&p->uf_entry.tv.head, &p->validated);
> +	mutex_unlock(&p->mutex_validated);
>   
>   	/* Get userptr backing pages. If pages are updated after registered
>   	 * in amdgpu_gem_userptr_ioctl(), amdgpu_cs_list_validate() will do
> @@ -563,8 +566,11 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>   		e->user_invalidated = userpage_invalidated;
>   	}
>   
> +	mutex_lock(&p->mutex_validated);
>   	r = ttm_eu_reserve_buffers(&p->ticket, &p->validated, true,
>   				   &duplicates);
> +	mutex_unlock(&p->mutex_validated);
> +
>   	if (unlikely(r != 0)) {
>   		if (r != -ERESTARTSYS)
>   			DRM_ERROR("ttm_eu_reserve_buffers failed.\n");
> @@ -607,11 +613,15 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>   		goto error_validate;
>   	}
>   
> +	mutex_lock(&p->mutex_validated);
>   	r = amdgpu_cs_list_validate(p, &duplicates);
> -	if (r)
> +	if (r) {
> +		mutex_unlock(&p->mutex_validated);
>   		goto error_validate;
> +	}
>   
>   	r = amdgpu_cs_list_validate(p, &p->validated);
> +	mutex_unlock(&p->mutex_validated);
>   	if (r)
>   		goto error_validate;
>   
> @@ -648,7 +658,9 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>   			dma_fence_chain_free(e->chain);
>   			e->chain = NULL;
>   		}
> +		mutex_lock(&p->mutex_validated);
>   		ttm_eu_backoff_reservation(&p->ticket, &p->validated);
> +		mutex_unlock(&p->mutex_validated);
>   	}
>   
>   out_free_user_pages:
> @@ -670,8 +682,9 @@ static int amdgpu_cs_sync_rings(struct amdgpu_cs_parser *p)
>   {
>   	struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
>   	struct amdgpu_bo_list_entry *e;
> -	int r;
> +	int r = 0;
>   
> +	mutex_lock(&p->mutex_validated);
>   	list_for_each_entry(e, &p->validated, tv.head) {
>   		struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
>   		struct dma_resv *resv = bo->tbo.base.resv;
> @@ -682,9 +695,10 @@ static int amdgpu_cs_sync_rings(struct amdgpu_cs_parser *p)
>   		r = amdgpu_sync_resv(p->adev, &p->job->sync, resv, sync_mode,
>   				     &fpriv->vm);
>   		if (r)
> -			return r;
> +			break;
>   	}
> -	return 0;
> +	mutex_unlock(&p->mutex_validated);
> +	return r;
>   }
>   
>   /**
> @@ -709,8 +723,10 @@ static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser, int error,
>   			e->chain = NULL;
>   		}
>   
> +		mutex_lock(&parser->mutex_validated);
>   		ttm_eu_backoff_reservation(&parser->ticket,
>   					   &parser->validated);
> +		mutex_unlock(&parser->mutex_validated);
>   	}
>   
>   	for (i = 0; i < parser->num_post_deps; i++) {
> @@ -1307,7 +1323,9 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>   		e->chain = NULL;
>   	}
>   
> +	mutex_lock(&p->mutex_validated);
>   	ttm_eu_fence_buffer_objects(&p->ticket, &p->validated, p->fence);
> +	mutex_unlock(&p->mutex_validated);
>   	mutex_unlock(&p->adev->notifier_lock);
>   
>   	return 0;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
> index 30ecc4917f811d..284d1c03d65d0b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
> @@ -59,6 +59,10 @@ struct amdgpu_cs_parser {
>   	struct amdgpu_bo_list		*bo_list;
>   	struct amdgpu_mn		*mn;
>   	struct amdgpu_bo_list_entry	vm_pd;
> +
> +	/* Protect access to list "valided" below.
> +	 */
> +	struct mutex                    mutex_validated;
>   	struct list_head		validated;
>   	struct dma_fence		*fence;
>   	uint64_t			bytes_moved_threshold;
>
> base-commit: ab7e60938be74e21c723223e7eb96cac7b441e5e