[PATCH 2/2] drm/amdgpu: rework dma_resv handling v3
Christian König
ckoenig.leichtzumerken at gmail.com
Mon Jun 14 17:45:36 UTC 2021
Drop the workaround and instead implement a better solution.
Basically we are now chaining all submissions using a dma_fence_chain
container and adding them as exclusive fence to the dma_resv object.
This way other drivers can still sync to the single exclusive fence
while amdgpu only sync to fences from different processes.
v3: add the shared fence first before the exclusive one
Signed-off-by: Christian König <christian.koenig at amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h | 1 +
drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 62 ++++++++++++++++----
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 65 ---------------------
drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 3 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 2 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 1 -
6 files changed, 55 insertions(+), 79 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
index a130e766cbdb..c905a4cfc173 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
@@ -34,6 +34,7 @@ struct amdgpu_fpriv;
struct amdgpu_bo_list_entry {
struct ttm_validate_buffer tv;
struct amdgpu_bo_va *bo_va;
+ struct dma_fence_chain *chain;
uint32_t priority;
struct page **user_pages;
bool user_invalidated;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 9ce649a1a8d3..25655414e9c0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -572,6 +572,20 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
goto out;
}
+ amdgpu_bo_list_for_each_entry(e, p->bo_list) {
+ struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
+
+ e->bo_va = amdgpu_vm_bo_find(vm, bo);
+
+ if (bo->tbo.base.dma_buf && !amdgpu_bo_explicit_sync(bo)) {
+ e->chain = dma_fence_chain_alloc();
+ if (!e->chain) {
+ r = -ENOMEM;
+ goto error_validate;
+ }
+ }
+ }
+
amdgpu_cs_get_threshold_for_moves(p->adev, &p->bytes_moved_threshold,
&p->bytes_moved_vis_threshold);
p->bytes_moved = 0;
@@ -599,15 +613,6 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
gws = p->bo_list->gws_obj;
oa = p->bo_list->oa_obj;
- amdgpu_bo_list_for_each_entry(e, p->bo_list) {
- struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
-
- /* Make sure we use the exclusive slot for shared BOs */
- if (bo->prime_shared_count)
- e->tv.num_shared = 0;
- e->bo_va = amdgpu_vm_bo_find(vm, bo);
- }
-
if (gds) {
p->job->gds_base = amdgpu_bo_gpu_offset(gds) >> PAGE_SHIFT;
p->job->gds_size = amdgpu_bo_size(gds) >> PAGE_SHIFT;
@@ -629,8 +634,13 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
}
error_validate:
- if (r)
+ if (r) {
+ amdgpu_bo_list_for_each_entry(e, p->bo_list) {
+ dma_fence_chain_free(e->chain);
+ e->chain = NULL;
+ }
ttm_eu_backoff_reservation(&p->ticket, &p->validated);
+ }
out:
return r;
}
@@ -670,9 +680,17 @@ static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser, int error,
{
unsigned i;
- if (error && backoff)
+ if (error && backoff) {
+ struct amdgpu_bo_list_entry *e;
+
+ amdgpu_bo_list_for_each_entry(e, parser->bo_list) {
+ dma_fence_chain_free(e->chain);
+ e->chain = NULL;
+ }
+
ttm_eu_backoff_reservation(&parser->ticket,
&parser->validated);
+ }
for (i = 0; i < parser->num_post_deps; i++) {
drm_syncobj_put(parser->post_deps[i].syncobj);
@@ -1245,6 +1263,28 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
amdgpu_vm_move_to_lru_tail(p->adev, &fpriv->vm);
+ amdgpu_bo_list_for_each_entry(e, p->bo_list) {
+ struct dma_resv *resv = e->tv.bo->base.resv;
+ struct dma_fence_chain *chain = e->chain;
+
+ if (!chain)
+ continue;
+
+ /*
+ * Work around dma_resv shortcommings by wrapping up the
+ * submission in a dma_fence_chain and add it as exclusive
+ * fence, but first add the submission as shared fence to make
+ * sure that shared fences never signal before the exclusive
+ * one.
+ */
+ dma_fence_chain_init(chain, dma_resv_excl_fence(resv),
+ dma_fence_get(p->fence), 1);
+
+ dma_resv_add_shared_fence(resv, p->fence);
+ rcu_assign_pointer(resv->fence_excl, &chain->base);
+ e->chain = NULL;
+ }
+
ttm_eu_fence_buffer_objects(&p->ticket, &p->validated, p->fence);
mutex_unlock(&p->adev->notifier_lock);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index c3053b83b80c..23219fc3b28c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -42,48 +42,6 @@
#include <linux/pci-p2pdma.h>
#include <linux/pm_runtime.h>
-static int
-__dma_resv_make_exclusive(struct dma_resv *obj)
-{
- struct dma_fence **fences;
- unsigned int count;
- int r;
-
- if (!dma_resv_shared_list(obj)) /* no shared fences to convert */
- return 0;
-
- r = dma_resv_get_fences(obj, NULL, &count, &fences);
- if (r)
- return r;
-
- if (count == 0) {
- /* Now that was unexpected. */
- } else if (count == 1) {
- dma_resv_add_excl_fence(obj, fences[0]);
- dma_fence_put(fences[0]);
- kfree(fences);
- } else {
- struct dma_fence_array *array;
-
- array = dma_fence_array_create(count, fences,
- dma_fence_context_alloc(1), 0,
- false);
- if (!array)
- goto err_fences_put;
-
- dma_resv_add_excl_fence(obj, &array->base);
- dma_fence_put(&array->base);
- }
-
- return 0;
-
-err_fences_put:
- while (count--)
- dma_fence_put(fences[count]);
- kfree(fences);
- return -ENOMEM;
-}
-
/**
* amdgpu_dma_buf_attach - &dma_buf_ops.attach implementation
*
@@ -110,24 +68,6 @@ static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf,
if (r < 0)
goto out;
- r = amdgpu_bo_reserve(bo, false);
- if (unlikely(r != 0))
- goto out;
-
- /*
- * We only create shared fences for internal use, but importers
- * of the dmabuf rely on exclusive fences for implicitly
- * tracking write hazards. As any of the current fences may
- * correspond to a write, we need to convert all existing
- * fences on the reservation object into a single exclusive
- * fence.
- */
- r = __dma_resv_make_exclusive(bo->tbo.base.resv);
- if (r)
- goto out;
-
- bo->prime_shared_count++;
- amdgpu_bo_unreserve(bo);
return 0;
out:
@@ -150,9 +90,6 @@ static void amdgpu_dma_buf_detach(struct dma_buf *dmabuf,
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
- if (attach->dev->driver != adev->dev->driver && bo->prime_shared_count)
- bo->prime_shared_count--;
-
pm_runtime_mark_last_busy(adev_to_drm(adev)->dev);
pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
}
@@ -406,8 +343,6 @@ amdgpu_dma_buf_create_obj(struct drm_device *dev, struct dma_buf *dma_buf)
bo = gem_to_amdgpu_bo(gobj);
bo->allowed_domains = AMDGPU_GEM_DOMAIN_GTT;
bo->preferred_domains = AMDGPU_GEM_DOMAIN_GTT;
- if (dma_buf->ops != &amdgpu_dmabuf_ops)
- bo->prime_shared_count = 1;
dma_resv_unlock(resv);
return gobj;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 9cf4beaf646c..0780e8d18992 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -829,7 +829,8 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
break;
}
case AMDGPU_GEM_OP_SET_PLACEMENT:
- if (robj->prime_shared_count && (args->value & AMDGPU_GEM_DOMAIN_VRAM)) {
+ if (robj->tbo.base.import_attach &&
+ args->value & AMDGPU_GEM_DOMAIN_VRAM) {
r = -EINVAL;
amdgpu_bo_unreserve(robj);
break;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index b7a2070d90af..d13490975ac3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -892,7 +892,7 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
return -EINVAL;
/* A shared bo cannot be migrated to VRAM */
- if (bo->prime_shared_count || bo->tbo.base.import_attach) {
+ if (bo->tbo.base.import_attach) {
if (domain & AMDGPU_GEM_DOMAIN_GTT)
domain = AMDGPU_GEM_DOMAIN_GTT;
else
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
index 126df03a7066..c03dfd298f45 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
@@ -99,7 +99,6 @@ struct amdgpu_bo {
struct ttm_buffer_object tbo;
struct ttm_bo_kmap_obj kmap;
u64 flags;
- unsigned prime_shared_count;
/* per VM structure for page tables and with virtual addresses */
struct amdgpu_vm_bo_base *vm_bo;
/* Constant after initialization */
--
2.25.1
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