[PATCH v7 20/20] drm/i915/vm_bind: Async vm_unbind support

Niranjana Vishwanathapura niranjana.vishwanathapura at intel.com
Tue Nov 29 23:26:34 UTC 2022


On Wed, Nov 23, 2022 at 11:42:58AM +0000, Matthew Auld wrote:
>On 16/11/2022 00:37, Niranjana Vishwanathapura wrote:
>>On Tue, Nov 15, 2022 at 03:15:03PM -0800, Niranjana Vishwanathapura wrote:
>>>On Tue, Nov 15, 2022 at 08:33:47AM -0800, Niranjana 
>>>Vishwanathapura wrote:
>>>>On Tue, Nov 15, 2022 at 04:20:54PM +0000, Matthew Auld wrote:
>>>>>On 15/11/2022 16:15, Niranjana Vishwanathapura wrote:
>>>>>>On Tue, Nov 15, 2022 at 11:05:21AM +0000, Matthew Auld wrote:
>>>>>>>On 13/11/2022 07:57, Niranjana Vishwanathapura wrote:
>>>>>>>>Asynchronously unbind the vma upon vm_unbind call.
>>>>>>>>Fall back to synchronous unbind if backend doesn't support
>>>>>>>>async unbind or if async unbind fails.
>>>>>>>>
>>>>>>>>No need for vm_unbind out fence support as i915 will internally
>>>>>>>>handle all sequencing and user need not try to sequence any
>>>>>>>>operation with the unbind completion.
>>>>>>>>
>>>>>>>>v2: use i915_vma_destroy_async in vm_unbind ioctl
>>>>>>>>
>>>>>>>>Signed-off-by: Niranjana Vishwanathapura 
>>>>>>>><niranjana.vishwanathapura at intel.com>
>>>>>>>
>>>>>>>This only does it for non-partial vma, right? Or was that 
>>>>>>>changed somewhere?
>>>>>>>
>>>>>>
>>>>>>No, it applies to any vma (partial or non-partial).
>>>>>>It was so from the beginning.
>>>>>
>>>>>Doesn't __i915_vma_unbind_async() return an error when 
>>>>>mm.pages != vma->pages? IIRC this was discussed before. Just 
>>>>>trying to think about the consequences of this change.
>>>>
>>>>I am not seeing any such restriction. Let me probe and check if there
>>>>is any such restriction anywhere in the call chain.
>>>
>>>I checked and I am not seeing any restriction anywher in the call chain.
>>>
>>
>>Note that just like binding case, unbinding is also synchronous unless
>>there is a pending activity, in which case, it will be asynchronous.
>
>In __i915_vma_unbind_async() there is:
>
>if (i915_vma_is_pinned(vma) ||
>    &vma->obj->mm.rsgt->table != vma->resource->bi.pages)
>        return ERR_PTR(-EAGAIN);
>
>AFAICT we then also don't get any pipelined moves with such an object, 
>if there is such a binding present.

I had to remove this check as otherwise for VM_BIND (persistent) mappings,
it will alwasy be true and we will always endup with -EAGAIN.
Persistent mappings, as they support partial binding, can't have an sg
table which is just a pointer to object's sg table.

Niranjana

>
>>
>>Niranjana
>>
>>>Niranjana
>>>
>>>>
>>>>Niranjana
>>>>
>>>>>
>>>>>>
>>>>>>Niranjana
>>>>>>
>>>>>>>Reviewed-by: Matthew Auld <matthew.auld at intel.com>
>>>>>>>
>>>>>>>>---
>>>>>>>> .../drm/i915/gem/i915_gem_vm_bind_object.c    |  2 +-
>>>>>>>> drivers/gpu/drm/i915/i915_vma.c               | 51 
>>>>>>>>+++++++++++++++++--
>>>>>>>> drivers/gpu/drm/i915/i915_vma.h               |  1 +
>>>>>>>> include/uapi/drm/i915_drm.h                   |  3 +-
>>>>>>>> 4 files changed, 51 insertions(+), 6 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 d87d1210365b..36651b447966 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
>>>>>>>>@@ -210,7 +210,7 @@ static int 
>>>>>>>>i915_gem_vm_unbind_vma(struct i915_address_space *vm,
>>>>>>>>      */
>>>>>>>>     obj = vma->obj;
>>>>>>>>     i915_gem_object_lock(obj, NULL);
>>>>>>>>-    i915_vma_destroy(vma);
>>>>>>>>+    i915_vma_destroy_async(vma);
>>>>>>>>     i915_gem_object_unlock(obj);
>>>>>>>>     i915_gem_object_put(obj);
>>>>>>>>diff --git a/drivers/gpu/drm/i915/i915_vma.c 
>>>>>>>>b/drivers/gpu/drm/i915/i915_vma.c
>>>>>>>>index 7cf77c67d755..483d25f2425c 100644
>>>>>>>>--- a/drivers/gpu/drm/i915/i915_vma.c
>>>>>>>>+++ b/drivers/gpu/drm/i915/i915_vma.c
>>>>>>>>@@ -42,6 +42,8 @@
>>>>>>>> #include "i915_vma.h"
>>>>>>>> #include "i915_vma_resource.h"
>>>>>>>>+static struct dma_fence *__i915_vma_unbind_async(struct 
>>>>>>>>i915_vma *vma);
>>>>>>>>+
>>>>>>>> static inline void assert_vma_held_evict(const struct 
>>>>>>>>i915_vma *vma)
>>>>>>>> {
>>>>>>>>     /*
>>>>>>>>@@ -1713,7 +1715,7 @@ void i915_vma_reopen(struct i915_vma *vma)
>>>>>>>>     spin_unlock_irq(&gt->closed_lock);
>>>>>>>> }
>>>>>>>>-static void force_unbind(struct i915_vma *vma)
>>>>>>>>+static void force_unbind(struct i915_vma *vma, bool async)
>>>>>>>> {
>>>>>>>>     if (!drm_mm_node_allocated(&vma->node))
>>>>>>>>         return;
>>>>>>>>@@ -1727,7 +1729,21 @@ static void force_unbind(struct 
>>>>>>>>i915_vma *vma)
>>>>>>>>         i915_vma_set_purged(vma);
>>>>>>>>     atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
>>>>>>>>-    WARN_ON(__i915_vma_unbind(vma));
>>>>>>>>+    if (async) {
>>>>>>>>+        struct dma_fence *fence;
>>>>>>>>+
>>>>>>>>+        fence = __i915_vma_unbind_async(vma);
>>>>>>>>+        if (IS_ERR_OR_NULL(fence)) {
>>>>>>>>+            async = false;
>>>>>>>>+        } else {
>>>>>>>>+            dma_resv_add_fence(vma->obj->base.resv, fence,
>>>>>>>>+                       DMA_RESV_USAGE_READ);
>>>>>>>>+            dma_fence_put(fence);
>>>>>>>>+        }
>>>>>>>>+    }
>>>>>>>>+
>>>>>>>>+    if (!async)
>>>>>>>>+        WARN_ON(__i915_vma_unbind(vma));
>>>>>>>>     GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
>>>>>>>> }
>>>>>>>>@@ -1787,7 +1803,7 @@ void 
>>>>>>>>i915_vma_destroy_locked(struct i915_vma *vma)
>>>>>>>> {
>>>>>>>>     lockdep_assert_held(&vma->vm->mutex);
>>>>>>>>-    force_unbind(vma);
>>>>>>>>+    force_unbind(vma, false);
>>>>>>>>     list_del_init(&vma->vm_link);
>>>>>>>>     release_references(vma, vma->vm->gt, false);
>>>>>>>> }
>>>>>>>>@@ -1798,7 +1814,34 @@ void i915_vma_destroy(struct i915_vma *vma)
>>>>>>>>     bool vm_ddestroy;
>>>>>>>>     mutex_lock(&vma->vm->mutex);
>>>>>>>>-    force_unbind(vma);
>>>>>>>>+    force_unbind(vma, false);
>>>>>>>>+    list_del_init(&vma->vm_link);
>>>>>>>>+    vm_ddestroy = vma->vm_ddestroy;
>>>>>>>>+    vma->vm_ddestroy = false;
>>>>>>>>+
>>>>>>>>+    /* vma->vm may be freed when releasing vma->vm->mutex. */
>>>>>>>>+    gt = vma->vm->gt;
>>>>>>>>+    mutex_unlock(&vma->vm->mutex);
>>>>>>>>+    release_references(vma, gt, vm_ddestroy);
>>>>>>>>+}
>>>>>>>>+
>>>>>>>>+void i915_vma_destroy_async(struct i915_vma *vma)
>>>>>>>>+{
>>>>>>>>+    bool vm_ddestroy, async = vma->obj->mm.rsgt;
>>>>>>>>+    struct intel_gt *gt;
>>>>>>>>+
>>>>>>>>+    if (dma_resv_reserve_fences(vma->obj->base.resv, 1))
>>>>>>>>+        async = false;
>>>>>>>>+
>>>>>>>>+    mutex_lock(&vma->vm->mutex);
>>>>>>>>+    /*
>>>>>>>>+     * Ensure any asynchronous binding is complete while using
>>>>>>>>+     * async unbind as we will be releasing the vma here.
>>>>>>>>+     */
>>>>>>>>+    if (async && i915_active_wait(&vma->active))
>>>>>>>>+        async = false;
>>>>>>>>+
>>>>>>>>+    force_unbind(vma, async);
>>>>>>>>     list_del_init(&vma->vm_link);
>>>>>>>>     vm_ddestroy = vma->vm_ddestroy;
>>>>>>>>     vma->vm_ddestroy = false;
>>>>>>>>diff --git a/drivers/gpu/drm/i915/i915_vma.h 
>>>>>>>>b/drivers/gpu/drm/i915/i915_vma.h
>>>>>>>>index 737ef310d046..25f15965dab8 100644
>>>>>>>>--- a/drivers/gpu/drm/i915/i915_vma.h
>>>>>>>>+++ b/drivers/gpu/drm/i915/i915_vma.h
>>>>>>>>@@ -272,6 +272,7 @@ void i915_vma_reopen(struct i915_vma *vma);
>>>>>>>> void i915_vma_destroy_locked(struct i915_vma *vma);
>>>>>>>> void i915_vma_destroy(struct i915_vma *vma);
>>>>>>>>+void i915_vma_destroy_async(struct i915_vma *vma);
>>>>>>>> #define assert_vma_held(vma) 
>>>>>>>>dma_resv_assert_held((vma)->obj->base.resv)
>>>>>>>>diff --git a/include/uapi/drm/i915_drm.h 
>>>>>>>>b/include/uapi/drm/i915_drm.h
>>>>>>>>index e5600f358a15..431d40bb1dee 100644
>>>>>>>>--- a/include/uapi/drm/i915_drm.h
>>>>>>>>+++ b/include/uapi/drm/i915_drm.h
>>>>>>>>@@ -3969,7 +3969,8 @@ struct drm_i915_gem_vm_bind {
>>>>>>>>  * any error.
>>>>>>>>  *
>>>>>>>>  * VM_BIND/UNBIND ioctl calls executed on different CPU 
>>>>>>>>threads concurrently
>>>>>>>>- * are not ordered.
>>>>>>>>+ * are not ordered. Furthermore, parts of the VM_UNBIND 
>>>>>>>>operation can be done
>>>>>>>>+ * asynchronously.
>>>>>>>>  */
>>>>>>>> struct drm_i915_gem_vm_unbind {
>>>>>>>>     /** @vm_id: VM (address space) id to bind */


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