[Intel-gfx] [PATCH v3 07/17] drm/i915/vm_bind: Add support to handle object evictions
Niranjana Vishwanathapura
niranjana.vishwanathapura at intel.com
Mon Oct 10 16:11:48 UTC 2022
On Mon, Oct 10, 2022 at 02:30:49PM +0100, Matthew Auld wrote:
>On 10/10/2022 07:58, Niranjana Vishwanathapura wrote:
>>Support eviction by maintaining a list of evicted persistent vmas
>>for rebinding during next submission. Ensure the list do not
>>include persistent vmas that are being purged.
>>
>>v2: Remove unused I915_VMA_PURGED definition.
>>v3: Properly handle __i915_vma_unbind_async() case.
>>
>>Acked-by: Matthew Auld <matthew.auld at intel.com>
>>Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
>>Signed-off-by: Andi Shyti <andi.shyti at linux.intel.com>
>>---
>> .../drm/i915/gem/i915_gem_vm_bind_object.c | 6 ++++
>> drivers/gpu/drm/i915/gt/intel_gtt.c | 2 ++
>> drivers/gpu/drm/i915/gt/intel_gtt.h | 4 +++
>> drivers/gpu/drm/i915/i915_vma.c | 31 +++++++++++++++++--
>> drivers/gpu/drm/i915/i915_vma.h | 10 ++++++
>> drivers/gpu/drm/i915/i915_vma_types.h | 8 +++++
>> 6 files changed, 59 insertions(+), 2 deletions(-)
>>
>>diff --git a/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c b/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
>>index 8e3e6ceb9442..c435d49af2c8 100644
>>--- a/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
>>+++ b/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
>>@@ -85,6 +85,12 @@ static void i915_gem_vm_bind_remove(struct i915_vma *vma, bool release_obj)
>> {
>> lockdep_assert_held(&vma->vm->vm_bind_lock);
>>+ spin_lock(&vma->vm->vm_rebind_lock);
>>+ if (!list_empty(&vma->vm_rebind_link))
>>+ list_del_init(&vma->vm_rebind_link);
>>+ i915_vma_set_purged(vma);
>>+ spin_unlock(&vma->vm->vm_rebind_lock);
>>+
>> list_del_init(&vma->vm_bind_link);
>> list_del_init(&vma->non_priv_vm_bind_link);
>> i915_vm_bind_it_remove(vma, &vma->vm->va);
>>diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
>>index 422394f8fb40..2fa37f46750b 100644
>>--- a/drivers/gpu/drm/i915/gt/intel_gtt.c
>>+++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
>>@@ -295,6 +295,8 @@ void i915_address_space_init(struct i915_address_space *vm, int subclass)
>> INIT_LIST_HEAD(&vm->vm_bound_list);
>> mutex_init(&vm->vm_bind_lock);
>> INIT_LIST_HEAD(&vm->non_priv_vm_bind_list);
>>+ INIT_LIST_HEAD(&vm->vm_rebind_list);
>>+ spin_lock_init(&vm->vm_rebind_lock);
>> }
>> void *__px_vaddr(struct drm_i915_gem_object *p)
>>diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
>>index 4ae5734f7d6b..443d1918ad4e 100644
>>--- a/drivers/gpu/drm/i915/gt/intel_gtt.h
>>+++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
>>@@ -265,6 +265,10 @@ struct i915_address_space {
>> struct list_head vm_bind_list;
>> /** @vm_bound_list: List of vm_binding completed */
>> struct list_head vm_bound_list;
>>+ /* @vm_rebind_list: list of vmas to be rebinded */
>>+ struct list_head vm_rebind_list;
>>+ /* @vm_rebind_lock: protects vm_rebound_list */
>>+ spinlock_t vm_rebind_lock;
>> /* @va: tree of persistent vmas */
>> struct rb_root_cached va;
>> struct list_head non_priv_vm_bind_list;
>>diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
>>index 5d3d67a4bf47..b4be2cbe8382 100644
>>--- a/drivers/gpu/drm/i915/i915_vma.c
>>+++ b/drivers/gpu/drm/i915/i915_vma.c
>>@@ -241,6 +241,7 @@ vma_create(struct drm_i915_gem_object *obj,
>> INIT_LIST_HEAD(&vma->vm_bind_link);
>> INIT_LIST_HEAD(&vma->non_priv_vm_bind_link);
>>+ INIT_LIST_HEAD(&vma->vm_rebind_link);
>> return vma;
>> err_unlock:
>>@@ -1686,6 +1687,14 @@ static void force_unbind(struct i915_vma *vma)
>> if (!drm_mm_node_allocated(&vma->node))
>> return;
>>+ /*
>>+ * Persistent vma should have been purged by now.
>>+ * If not, issue a warning and purge it.
>>+ */
>>+ if (GEM_WARN_ON(i915_vma_is_persistent(vma) &&
>>+ !i915_vma_is_purged(vma)))
>>+ i915_vma_set_purged(vma);
>>+
>> atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
>> WARN_ON(__i915_vma_unbind(vma));
>> GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
>>@@ -2047,6 +2056,16 @@ int __i915_vma_unbind(struct i915_vma *vma)
>> __i915_vma_evict(vma, false);
>> drm_mm_remove_node(&vma->node); /* pairs with i915_vma_release() */
>>+
>>+ if (i915_vma_is_persistent(vma)) {
>>+ spin_lock(&vma->vm->vm_rebind_lock);
>>+ if (list_empty(&vma->vm_rebind_link) &&
>>+ !i915_vma_is_purged(vma))
>>+ list_add_tail(&vma->vm_rebind_link,
>>+ &vma->vm->vm_rebind_list);
>>+ spin_unlock(&vma->vm->vm_rebind_lock);
>>+ }
>>+
>> return 0;
>> }
>>@@ -2059,8 +2078,7 @@ static struct dma_fence *__i915_vma_unbind_async(struct i915_vma *vma)
>> if (!drm_mm_node_allocated(&vma->node))
>> return NULL;
>>- if (i915_vma_is_pinned(vma) ||
>>- &vma->obj->mm.rsgt->table != vma->resource->bi.pages)
>
>Hmm that's looks interesting. IIRC we only keep a ref on the rsgt for
>the object pages, and not the vma->bi.pages, where the vma pages can
>be destroyed before the async unbind completes, which I guess was the
>idea behind this check.
>
>But in practice it looks the vma->bi.pages are always just some subset
>or rearrangement of the objects rsgt pages, if not the same table, so
>the device mapping pointed at by the PTEs should still be valid here
>(assuming rsgt in not NULL), even if bi.pages gets nuked? I guess this
>change should rather be a patch by itself, with proper explanation in
>commit message, since this looks mostly orthogonal?
>
Yah, I am not sure about the intent of this check. It is expecting the
vma->resource->bi.pages to just point to the sg table of the object
(vma->obj->mm.rsgt->table) which is reference counted, instead of
decoupling it as you mentioned above. Also, the return code -EAGAIN
is bit confusing to me as I am not sure how trying again will fix it.
This check was preventing eviction of objects with persistent (vm_bind)
vmas (Hence the update is in this patch).
Persistent vmas have I915_GTT_VIEW_PARTIAL, so they will get their sg table
by calling intel_partial_pages() which creates a new sg table instead of
pointing to object's sg table (as done in the I915_GTT_VIEW_NORMAL case).]
If the vma is removed before async unbind completes, we probably
should wait for async unbind to complete before releaseing the vma
pages? Other option is to have vma point to object's sg table even for
partial gtt_view (instead of creating a new sg table) and handle
partial binding during the page table update.
I can also keep the above removed check and only don't check it for
persistent vmas.
Any thoughts?
Niranjana
>>+ if (i915_vma_is_pinned(vma))
>> return ERR_PTR(-EAGAIN);
>> /*
>>@@ -2082,6 +2100,15 @@ static struct dma_fence *__i915_vma_unbind_async(struct i915_vma *vma)
>> drm_mm_remove_node(&vma->node); /* pairs with i915_vma_release() */
>>+ if (i915_vma_is_persistent(vma)) {
>>+ spin_lock(&vma->vm->vm_rebind_lock);
>>+ if (list_empty(&vma->vm_rebind_link) &&
>>+ !i915_vma_is_purged(vma))
>>+ list_add_tail(&vma->vm_rebind_link,
>>+ &vma->vm->vm_rebind_list);
>>+ spin_unlock(&vma->vm->vm_rebind_lock);
>>+ }
>>+
>> return fence;
>> }
>>diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
>>index c5378ec2f70a..9a4a7a8dfe5b 100644
>>--- a/drivers/gpu/drm/i915/i915_vma.h
>>+++ b/drivers/gpu/drm/i915/i915_vma.h
>>@@ -152,6 +152,16 @@ static inline void i915_vma_set_persistent(struct i915_vma *vma)
>> set_bit(I915_VMA_PERSISTENT_BIT, __i915_vma_flags(vma));
>> }
>>+static inline bool i915_vma_is_purged(const struct i915_vma *vma)
>>+{
>>+ return test_bit(I915_VMA_PURGED_BIT, __i915_vma_flags(vma));
>>+}
>>+
>>+static inline void i915_vma_set_purged(struct i915_vma *vma)
>>+{
>>+ set_bit(I915_VMA_PURGED_BIT, __i915_vma_flags(vma));
>>+}
>>+
>> static inline struct i915_vma *i915_vma_get(struct i915_vma *vma)
>> {
>> i915_gem_object_get(vma->obj);
>>diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
>>index b8176cca58c0..d32c72e8d242 100644
>>--- a/drivers/gpu/drm/i915/i915_vma_types.h
>>+++ b/drivers/gpu/drm/i915/i915_vma_types.h
>>@@ -267,8 +267,14 @@ struct i915_vma {
>> /**
>> * I915_VMA_PERSISTENT_BIT:
>> * The vma is persistent (created with VM_BIND call).
>>+ *
>>+ * I915_VMA_PURGED_BIT:
>>+ * The persistent vma is force unbound either due to VM_UNBIND call
>>+ * from UMD or VM is released. Do not check/wait for VM activeness
>>+ * in i915_vma_is_active() and i915_vma_sync() calls.
>> */
>> #define I915_VMA_PERSISTENT_BIT 19
>>+#define I915_VMA_PURGED_BIT 20
>> struct i915_active active;
>>@@ -299,6 +305,8 @@ struct i915_vma {
>> struct list_head vm_bind_link;
>> /* @non_priv_vm_bind_link: Link in non-private persistent VMA list */
>> struct list_head non_priv_vm_bind_link;
>>+ /* @vm_rebind_link: link to vm_rebind_list and protected by vm_rebind_lock */
>>+ struct list_head vm_rebind_link; /* Link in vm_rebind_list */
>> /** Interval tree structures for persistent vma */
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