[Intel-gfx] [PATCH 24/28] drm/i915: Add i915_vma_unbind_unlocked, and take obj lock for i915_vma_unbind

Maarten Lankhorst
2021-10-21T10:37:14Z

We want to remove more members of i915_vma, which requires the locking to be
held more often.

Start requiring gem object lock for i915_vma_unbind, as it's one of the
callers that may unpin pages.

Some special care is needed when evicting, because the last reference to the
object may be held by the VMA, so after __i915_vma_unbind, vma may be garbage,
and we need to cache vma->obj before unlocking.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
drivers/gpu/drm/i915/display/intel_fb_pin.c | 2 +-
.../gpu/drm/i915/gem/selftests/huge_pages.c | 2 +-
.../i915/gem/selftests/i915_gem_client_blt.c | 2 +-
.../drm/i915/gem/selftests/i915_gem_mman.c | 6 +++
drivers/gpu/drm/i915/gt/intel_ggtt.c | 45 ++++++++++++++++---
drivers/gpu/drm/i915/i915_gem.c | 2 +
drivers/gpu/drm/i915/i915_vma.c | 27 ++++++++++-
drivers/gpu/drm/i915/i915_vma.h | 1 +
drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 22 ++++-----
drivers/gpu/drm/i915/selftests/i915_vma.c | 8 ++--
10 files changed, 91 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fb_pin.c b/drivers/gpu/drm/i915/display/intel_fb_pin.c
index 3f77f3013584..1c0ff2ef3937 100644
--- a/drivers/gpu/drm/i915/display/intel_fb_pin.c
+++ b/drivers/gpu/drm/i915/display/intel_fb_pin.c
@@ -47,7 +47,7 @@ intel_pin_fb_obj_dpt(struct drm_framebuffer *fb,
goto err;

if (i915_vma_misplaced(vma, 0, alignment, 0)) {
- ret = i915_vma_unbind(vma);
+ ret = i915_vma_unbind_unlocked(vma);
if (ret) {
vma = ERR_PTR(ret);
goto err;
diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
index 493509f90b35..97473ac7c7f7 100644
--- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
@@ -646,7 +646,7 @@ static int igt_mock_ppgtt_misaligned_dma(void *arg)
* pages.
*/
for (offset = 4096; offset < page_size; offset += 4096) {
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err)
goto out_unpin;

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
index 8402ed925a69..8fb5be799b3c 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
@@ -318,7 +318,7 @@ static int pin_buffer(struct i915_vma *vma, u64 addr)
int err;

if (drm_mm_node_allocated(&vma->node) && vma->node.start != addr) {
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err)
return err;
}
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
index 6d30cdfa80f3..e69e8861352d 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
@@ -165,7 +165,9 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
kunmap(p);

out:
+ i915_gem_object_lock(obj, NULL);
__i915_vma_put(vma);
+ i915_gem_object_unlock(obj);
return err;
}

@@ -259,7 +261,9 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
if (err)
return err;

+ i915_gem_object_lock(obj, NULL);
__i915_vma_put(vma);
+ i915_gem_object_unlock(obj);

if (igt_timeout(end_time,
"%s: timed out after tiling=%d stride=%d\n",
@@ -1349,7 +1353,9 @@ static int __igt_mmap_revoke(struct drm_i915_private *i915,
* for other objects. Ergo we have to revoke the previous mmap PTE
* access as it no longer points to the same object.
*/
+ i915_gem_object_lock(obj, NULL);
err = i915_gem_object_unbind(obj, I915_GEM_OBJECT_UNBIND_ACTIVE);
+ i915_gem_object_unlock(obj);
if (err) {
pr_err("Failed to unbind object!\n");
goto out_unmap;
diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
index df29fd992b45..44bc30458cac 100644
--- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
@@ -118,22 +118,45 @@ void i915_ggtt_suspend(struct i915_ggtt *ggtt)
struct i915_vma *vma, *vn;
int open;

+retry:
+ i915_gem_drain_freed_objects(ggtt->vm.i915);
+
mutex_lock(&ggtt->vm.mutex);

/* Skip rewriting PTE on VMA unbind. */
open = atomic_xchg(&ggtt->vm.open, 0);

list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link) {
+ struct drm_i915_gem_object *obj = vma->obj;
+
GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
- i915_vma_wait_for_bind(vma);

- if (i915_vma_is_pinned(vma))
+ if (i915_vma_is_pinned(vma) || !i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND))
continue;

- if (!i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND)) {
- __i915_vma_evict(vma);
- drm_mm_remove_node(&vma->node);
+ /* unlikely to race when GPU is idle, so no worry about slowpath.. */
+ if (!i915_gem_object_trylock(obj, NULL)) {
+ atomic_set(&ggtt->vm.open, open);
+
+ i915_gem_object_get(obj);
+ mutex_unlock(&ggtt->vm.mutex);
+
+ i915_gem_object_lock(obj, NULL);
+ open = i915_vma_unbind(vma);
+ i915_gem_object_unlock(obj);
+
+ GEM_WARN_ON(open);
+
+ i915_gem_object_put(obj);
+ goto retry;
}
+
+ i915_vma_wait_for_bind(vma);
+
+ __i915_vma_evict(vma);
+ drm_mm_remove_node(&vma->node);
+
+ i915_gem_object_unlock(obj);
}

ggtt->vm.clear_range(&ggtt->vm, 0, ggtt->vm.total);
@@ -725,11 +748,21 @@ static void ggtt_cleanup_hw(struct i915_ggtt *ggtt)
atomic_set(&ggtt->vm.open, 0);

flush_workqueue(ggtt->vm.i915->wq);
+ i915_gem_drain_freed_objects(ggtt->vm.i915);

mutex_lock(&ggtt->vm.mutex);

- list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link)
+ list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link) {
+ struct drm_i915_gem_object *obj = vma->obj;
+ bool trylock;
+
+ trylock = i915_gem_object_trylock(obj, NULL);
+ WARN_ON(!trylock);
+
WARN_ON(__i915_vma_unbind(vma));
+ if (trylock)
+ i915_gem_object_unlock(obj);
+ }

if (drm_mm_node_allocated(&ggtt->error_capture))
drm_mm_remove_node(&ggtt->error_capture);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6aa9e465b48e..d45abf05987d 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -118,6 +118,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
struct i915_vma *vma;
int ret;

+ assert_object_held(obj);
+
if (list_empty(&obj->vma.list))
return 0;

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 3275b2364785..982bb8b739d3 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -1508,8 +1508,16 @@ void i915_vma_parked(struct intel_gt *gt)
struct drm_i915_gem_object *obj = vma->obj;
struct i915_address_space *vm = vma->vm;

- INIT_LIST_HEAD(&vma->closed_link);
- __i915_vma_put(vma);
+ if (i915_gem_object_trylock(obj, NULL)) {
+ INIT_LIST_HEAD(&vma->closed_link);
+ __i915_vma_put(vma);
+ i915_gem_object_unlock(obj);
+ } else {
+ /* back you go.. */
+ spin_lock_irq(&gt->closed_lock);
+ list_add(&vma->closed_link, &gt->closed_vma);
+ spin_unlock_irq(&gt->closed_lock);
+ }

i915_gem_object_put(obj);
i915_vm_close(vm);
@@ -1625,6 +1633,7 @@ int _i915_vma_move_to_active(struct i915_vma *vma,
void __i915_vma_evict(struct i915_vma *vma)
{
GEM_BUG_ON(i915_vma_is_pinned(vma));
+ assert_object_held_shared(vma->obj);

if (i915_vma_is_map_and_fenceable(vma)) {
/* Force a pagefault for domain tracking on next user access */
@@ -1670,6 +1679,7 @@ int __i915_vma_unbind(struct i915_vma *vma)
int ret;

lockdep_assert_held(&vma->vm->mutex);
+ assert_object_held_shared(vma->obj);

if (!drm_mm_node_allocated(&vma->node))
return 0;
@@ -1701,6 +1711,8 @@ int i915_vma_unbind(struct i915_vma *vma)
intel_wakeref_t wakeref = 0;
int err;

+ assert_object_held_shared(vma->obj);
+
/* Optimistic wait before taking the mutex */
err = i915_vma_sync(vma);
if (err)
@@ -1731,6 +1743,17 @@ int i915_vma_unbind(struct i915_vma *vma)
return err;
}

+int i915_vma_unbind_unlocked(struct i915_vma *vma)
+{
+ int err;
+
+ i915_gem_object_lock(vma->obj, NULL);
+ err = i915_vma_unbind(vma);
+ i915_gem_object_unlock(vma->obj);
+
+ return err;
+}
+
struct i915_vma *i915_vma_make_unshrinkable(struct i915_vma *vma)
{
i915_gem_object_make_unshrinkable(vma->obj);
diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index 32719431b3df..da69ecb1b860 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -214,6 +214,7 @@ void i915_vma_revoke_mmap(struct i915_vma *vma);
void __i915_vma_evict(struct i915_vma *vma);
int __i915_vma_unbind(struct i915_vma *vma);
int __must_check i915_vma_unbind(struct i915_vma *vma);
+int __must_check i915_vma_unbind_unlocked(struct i915_vma *vma);
void i915_vma_unlink_ctx(struct i915_vma *vma);
void i915_vma_close(struct i915_vma *vma);
void i915_vma_reopen(struct i915_vma *vma);
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 6b1db83119b3..de16897d3d9a 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
@@ -385,7 +385,7 @@ static void close_object_list(struct list_head *objects,

vma = i915_vma_instance(obj, vm, NULL);
if (!IS_ERR(vma))
- ignored = i915_vma_unbind(vma);
+ ignored = i915_vma_unbind_unlocked(vma);

list_del(&obj->st_link);
i915_gem_object_put(obj);
@@ -496,7 +496,7 @@ static int fill_hole(struct i915_address_space *vm,
goto err;
}

- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("%s(%s) (forward) unbind of vma.node=%llx + %llx failed with err=%d\n",
__func__, p->name, vma->node.start, vma->node.size,
@@ -569,7 +569,7 @@ static int fill_hole(struct i915_address_space *vm,
goto err;
}

- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("%s(%s) (backward) unbind of vma.node=%llx + %llx failed with err=%d\n",
__func__, p->name, vma->node.start, vma->node.size,
@@ -655,7 +655,7 @@ static int walk_hole(struct i915_address_space *vm,
goto err_put;
}

- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("%s unbind failed at %llx + %llx with err=%d\n",
__func__, addr, vma->size, err);
@@ -732,13 +732,13 @@ static int pot_hole(struct i915_address_space *vm,
pr_err("%s incorrect at %llx + %llx\n",
__func__, addr, vma->size);
i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
err = -EINVAL;
goto err_obj;
}

i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
GEM_BUG_ON(err);
}

@@ -832,13 +832,13 @@ static int drunk_hole(struct i915_address_space *vm,
pr_err("%s incorrect at %llx + %llx\n",
__func__, addr, BIT_ULL(size));
i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
err = -EINVAL;
goto err_obj;
}

i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
GEM_BUG_ON(err);

if (igt_timeout(end_time,
@@ -906,7 +906,7 @@ static int __shrink_hole(struct i915_address_space *vm,
pr_err("%s incorrect at %llx + %llx\n",
__func__, addr, size);
i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
err = -EINVAL;
break;
}
@@ -1465,7 +1465,7 @@ static int igt_gtt_reserve(void *arg)
goto out;
}

- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("i915_vma_unbind failed with err=%d!\n", err);
goto out;
@@ -1647,7 +1647,7 @@ static int igt_gtt_insert(void *arg)
GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
offset = vma->node.start;

- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("i915_vma_unbind failed with err=%d!\n", err);
goto out;
diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c b/drivers/gpu/drm/i915/selftests/i915_vma.c
index 5c5809dfe9b2..2c73f7448df7 100644
--- a/drivers/gpu/drm/i915/selftests/i915_vma.c
+++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
@@ -340,7 +340,7 @@ static int igt_vma_pin1(void *arg)

if (!err) {
i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("Failed to unbind single page from GGTT, err=%d\n", err);
goto out;
@@ -691,7 +691,7 @@ static int igt_vma_rotate_remap(void *arg)
}

i915_vma_unpin(vma);
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("Unbinding returned %i\n", err);
goto out_object;
@@ -852,7 +852,7 @@ static int igt_vma_partial(void *arg)

i915_vma_unpin(vma);
nvma++;
- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("Unbinding returned %i\n", err);
goto out_object;
@@ -891,7 +891,7 @@ static int igt_vma_partial(void *arg)

i915_vma_unpin(vma);

- err = i915_vma_unbind(vma);
+ err = i915_vma_unbind_unlocked(vma);
if (err) {
pr_err("Unbinding returned %i\n", err);
goto out_object;
--
2.33.0