Re: [Intel-gfx] [PATCH v4 16/17] drm/i915/vm_bind: userptr dma-resv changes

[Matthew Auld <matthew.auld@intel.com>]

On 18/10/2022 08:16, Niranjana Vishwanathapura wrote:
> For persistent (vm_bind) vmas of userptr BOs, handle the user
> page pinning by using the i915_gem_object_userptr_submit_init()
> /done() functions
> 
> v2: Do not double add vma to vm->userptr_invalidated_list
> 
> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
> ---
>   .../gpu/drm/i915/gem/i915_gem_execbuffer3.c   | 80 +++++++++++++++++++
>   drivers/gpu/drm/i915/gem/i915_gem_userptr.c   | 19 +++++
>   .../drm/i915/gem/i915_gem_vm_bind_object.c    | 15 ++++
>   drivers/gpu/drm/i915/gt/intel_gtt.c           |  2 +
>   drivers/gpu/drm/i915/gt/intel_gtt.h           |  4 +
>   drivers/gpu/drm/i915/i915_vma_types.h         |  2 +
>   6 files changed, 122 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer3.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer3.c
> index 8120e4c6b7da..3f1157dd7fc2 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer3.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer3.c
> @@ -20,6 +20,7 @@
>   #include "i915_gem_vm_bind.h"
>   #include "i915_trace.h"
>   
> +#define __EXEC3_USERPTR_USED		BIT_ULL(34)
>   #define __EXEC3_HAS_PIN			BIT_ULL(33)
>   #define __EXEC3_ENGINE_PINNED		BIT_ULL(32)
>   #define __EXEC3_INTERNAL_FLAGS		(~0ull << 32)
> @@ -142,6 +143,21 @@ static void eb_scoop_unbound_vma_all(struct i915_address_space *vm)
>   {
>   	struct i915_vma *vma, *vn;
>   
> +#ifdef CONFIG_MMU_NOTIFIER
> +	/**

Not proper kernel-doc AFAIK.

> +	 * Move all invalidated userptr vmas back into vm_bind_list so that
> +	 * they are looked up and revalidated.
> +	 */
> +	spin_lock(&vm->userptr_invalidated_lock);
> +	list_for_each_entry_safe(vma, vn, &vm->userptr_invalidated_list,
> +				 userptr_invalidated_link) {
> +		list_del_init(&vma->userptr_invalidated_link);
> +		if (!list_empty(&vma->vm_bind_link))
> +			list_move_tail(&vma->vm_bind_link, &vm->vm_bind_list);
> +	}
> +	spin_unlock(&vm->userptr_invalidated_lock);
> +#endif
> +
>   	/**
>   	 * Move all unbound vmas back into vm_bind_list so that they are
>   	 * revalidated.
> @@ -155,10 +171,47 @@ static void eb_scoop_unbound_vma_all(struct i915_address_space *vm)
>   	spin_unlock(&vm->vm_rebind_lock);
>   }
>   
> +static int eb_lookup_persistent_userptr_vmas(struct i915_execbuffer *eb)
> +{
> +	struct i915_address_space *vm = eb->context->vm;
> +	struct i915_vma *last_vma = NULL;
> +	struct i915_vma *vma;
> +	int err;
> +
> +	lockdep_assert_held(&vm->vm_bind_lock);
> +
> +	list_for_each_entry(vma, &vm->vm_bind_list, vm_bind_link) {
> +		if (!i915_gem_object_is_userptr(vma->obj))
> +			continue;
> +
> +		err = i915_gem_object_userptr_submit_init(vma->obj);
> +		if (err)
> +			return err;
> +
> +		/**
> +		 * The above submit_init() call does the object unbind and
> +		 * hence adds vma into vm_rebind_list. Remove it from that
> +		 * list as it is already scooped for revalidation.
> +		 */

Ditto.

> +		spin_lock(&vm->vm_rebind_lock);
> +		if (!list_empty(&vma->vm_rebind_link))
> +			list_del_init(&vma->vm_rebind_link);
> +		spin_unlock(&vm->vm_rebind_lock);
> +
> +		last_vma = vma;
> +	}
> +
> +	if (last_vma)
> +		eb->args->flags |= __EXEC3_USERPTR_USED;
> +
> +	return 0;
> +}
> +
>   static int eb_lookup_vma_all(struct i915_execbuffer *eb)
>   {
>   	unsigned int i, current_batch = 0;
>   	struct i915_vma *vma;
> +	int err = 0;
>   
>   	for (i = 0; i < eb->num_batches; i++) {
>   		vma = eb_find_vma(eb->context->vm, eb->batch_addresses[i]);
> @@ -171,6 +224,10 @@ static int eb_lookup_vma_all(struct i915_execbuffer *eb)
>   
>   	eb_scoop_unbound_vma_all(eb->context->vm);
>   
> +	err = eb_lookup_persistent_userptr_vmas(eb);
> +	if (err)
> +		return err;
> +
>   	return 0;
>   }
>   
> @@ -343,6 +400,29 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb)
>   		}
>   	}
>   
> +#ifdef CONFIG_MMU_NOTIFIER
> +	/* Check for further userptr invalidations */
> +	spin_lock(&vm->userptr_invalidated_lock);
> +	if (!list_empty(&vm->userptr_invalidated_list))
> +		err = -EAGAIN;
> +	spin_unlock(&vm->userptr_invalidated_lock);

After dropping the lock here, the invalidated_list might no longer be 
empty? Is that not possible, or somehow not a concern?

> +
> +	if (!err && (eb->args->flags & __EXEC3_USERPTR_USED)) {
> +		read_lock(&eb->i915->mm.notifier_lock);
> +		list_for_each_entry(vma, &vm->vm_bind_list, vm_bind_link) {
> +			if (!i915_gem_object_is_userptr(vma->obj))
> +				continue;
> +
> +			err = i915_gem_object_userptr_submit_done(vma->obj);
> +			if (err)
> +				break;
> +		}
> +		read_unlock(&eb->i915->mm.notifier_lock);
> +	}
> +#endif
> +	if (unlikely(err))
> +		goto err_skip;
> +
>   	/* Unconditionally flush any chipset caches (for streaming writes). */
>   	intel_gt_chipset_flush(eb->gt);
>   
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
> index b7e24476a0fd..3e88fd4d46b6 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
> @@ -63,6 +63,7 @@ static bool i915_gem_userptr_invalidate(struct mmu_interval_notifier *mni,
>   {
>   	struct drm_i915_gem_object *obj = container_of(mni, struct drm_i915_gem_object, userptr.notifier);
>   	struct drm_i915_private *i915 = to_i915(obj->base.dev);
> +	struct i915_vma *vma;
>   	long r;
>   
>   	if (!mmu_notifier_range_blockable(range))
> @@ -85,6 +86,24 @@ static bool i915_gem_userptr_invalidate(struct mmu_interval_notifier *mni,
>   	if (current->flags & PF_EXITING)
>   		return true;
>   
> +	/**
> +	 * Add persistent vmas into userptr_invalidated list for relookup
> +	 * and revalidation.
> +	 */

Ditto.

> +	spin_lock(&obj->vma.lock);
> +	list_for_each_entry(vma, &obj->vma.list, obj_link) {
> +		if (!i915_vma_is_persistent(vma))
> +			continue;
> +
> +		spin_lock(&vma->vm->userptr_invalidated_lock);
> +		if (list_empty(&vma->userptr_invalidated_link) &&
> +		    !i915_vma_is_purged(vma))
> +			list_add_tail(&vma->userptr_invalidated_link,
> +				      &vma->vm->userptr_invalidated_list);
> +		spin_unlock(&vma->vm->userptr_invalidated_lock);
> +	}
> +	spin_unlock(&obj->vma.lock);
> +
>   	/* we will unbind on next submission, still have userptr pins */
>   	r = dma_resv_wait_timeout(obj->base.resv, DMA_RESV_USAGE_BOOKKEEP, false,
>   				  MAX_SCHEDULE_TIMEOUT);
> 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 63889ba00183..19071493355c 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
> @@ -299,6 +299,12 @@ static int i915_gem_vm_bind_obj(struct i915_address_space *vm,
>   		goto put_obj;
>   	}
>   
> +	if (i915_gem_object_is_userptr(obj)) {
> +		ret = i915_gem_object_userptr_submit_init(obj);
> +		if (ret)
> +			goto put_obj;
> +	}
> +
>   	ret = mutex_lock_interruptible(&vm->vm_bind_lock);
>   	if (ret)
>   		goto put_obj;
> @@ -327,6 +333,15 @@ static int i915_gem_vm_bind_obj(struct i915_address_space *vm,
>   		if (ret)
>   			continue;
>   
> +#ifdef CONFIG_MMU_NOTIFIER
> +		if (i915_gem_object_is_userptr(obj)) {
> +			read_lock(&vm->i915->mm.notifier_lock);
> +			ret = i915_gem_object_userptr_submit_done(obj);
> +			read_unlock(&vm->i915->mm.notifier_lock);
> +			if (ret)
> +				continue;
> +		}
> +#endif
>   		list_add_tail(&vma->vm_bind_link, &vm->vm_bound_list);
>   		i915_vm_bind_it_insert(vma, &vm->va);
>   		if (!obj->priv_root)
> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
> index ebf8fc3a4603..50648ab9214a 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gtt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
> @@ -292,6 +292,8 @@ void i915_address_space_init(struct i915_address_space *vm, int subclass)
>   	INIT_LIST_HEAD(&vm->non_priv_vm_bind_list);
>   	INIT_LIST_HEAD(&vm->vm_rebind_list);
>   	spin_lock_init(&vm->vm_rebind_lock);
> +	spin_lock_init(&vm->userptr_invalidated_lock);
> +	INIT_LIST_HEAD(&vm->userptr_invalidated_list);
>   }
>   
>   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 384d1ee7c68d..1ade95b2a0fa 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gtt.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
> @@ -270,6 +270,10 @@ struct i915_address_space {
>   	struct list_head vm_rebind_list;
>   	/* @vm_rebind_lock: protects vm_rebound_list */
>   	spinlock_t vm_rebind_lock;
> +	/* @userptr_invalidated_list: list of invalidated userptr vmas */
> +	struct list_head userptr_invalidated_list;
> +	/* @userptr_invalidated_lock: protects userptr_invalidated_list */
> +	spinlock_t userptr_invalidated_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_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
> index 2c740500ac1b..8e562e07d4a7 100644
> --- a/drivers/gpu/drm/i915/i915_vma_types.h
> +++ b/drivers/gpu/drm/i915/i915_vma_types.h
> @@ -307,6 +307,8 @@ struct i915_vma {
>   	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 */
> +	/*@userptr_invalidated_link: link to the vm->userptr_invalidated_list */
> +	struct list_head userptr_invalidated_link;
>   
>   	/** Timeline fence for vm_bind completion notification */
>   	struct {