Re: [PATCH v3 3/4] drm/i915/ttm: add unmap_virtual callback

[Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>]

On 1/6/22 18:49, Matthew Auld wrote:
> Ensure we call ttm_bo_unmap_virtual when releasing the pages.
> Importantly this should now handle the ttm swapping case, and all other
> places that already call into i915_ttm_move_notify().
>
> v2: fix up the selftest
>
> Fixes: cf3e3e86d779 ("drm/i915: Use ttm mmap handling for ttm bo's.")
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>

Hm.

I guess we've been saved here previously by the fact that TTM calls 
ttm_bo_unmap_virtual()
before calling the move callback.

Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>

> ---
>   drivers/gpu/drm/i915/gem/i915_gem_mman.c       |  3 +++
>   .../gpu/drm/i915/gem/i915_gem_object_types.h   |  1 +
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c        |  6 ++++++
>   .../gpu/drm/i915/gem/selftests/i915_gem_mman.c | 18 ++++--------------
>   4 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> index ee5ec0fd4807..5ac2506f4ee8 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> @@ -538,6 +538,9 @@ void i915_gem_object_release_mmap_offset(struct drm_i915_gem_object *obj)
>   {
>   	struct i915_mmap_offset *mmo, *mn;
>   
> +	if (obj->ops->unmap_virtual)
> +		obj->ops->unmap_virtual(obj);
> +
>   	spin_lock(&obj->mmo.lock);
>   	rbtree_postorder_for_each_entry_safe(mmo, mn,
>   					     &obj->mmo.offsets, offset) {
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> index f9f7e44099fe..4b4829eb16c2 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> @@ -67,6 +67,7 @@ struct drm_i915_gem_object_ops {
>   	int (*pwrite)(struct drm_i915_gem_object *obj,
>   		      const struct drm_i915_gem_pwrite *arg);
>   	u64 (*mmap_offset)(struct drm_i915_gem_object *obj);
> +	void (*unmap_virtual)(struct drm_i915_gem_object *obj);
>   
>   	int (*dmabuf_export)(struct drm_i915_gem_object *obj);
>   
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 8d61d4538a64..1530d9f0bc81 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -950,6 +950,11 @@ static u64 i915_ttm_mmap_offset(struct drm_i915_gem_object *obj)
>   	return drm_vma_node_offset_addr(&obj->base.vma_node);
>   }
>   
> +static void i915_ttm_unmap_virtual(struct drm_i915_gem_object *obj)
> +{
> +	ttm_bo_unmap_virtual(i915_gem_to_ttm(obj));
> +}
> +
>   static const struct drm_i915_gem_object_ops i915_gem_ttm_obj_ops = {
>   	.name = "i915_gem_object_ttm",
>   	.flags = I915_GEM_OBJECT_IS_SHRINKABLE |
> @@ -965,6 +970,7 @@ static const struct drm_i915_gem_object_ops i915_gem_ttm_obj_ops = {
>   	.migrate = i915_ttm_migrate,
>   
>   	.mmap_offset = i915_ttm_mmap_offset,
> +	.unmap_virtual = i915_ttm_unmap_virtual,
>   	.mmap_ops = &vm_ops_ttm,
>   };
>   
> 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 743a098facf2..f61356b72b1c 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
> @@ -1369,20 +1369,10 @@ static int __igt_mmap_revoke(struct drm_i915_private *i915,
>   		}
>   	}
>   
> -	if (!obj->ops->mmap_ops) {
> -		err = check_absent(addr, obj->base.size);
> -		if (err) {
> -			pr_err("%s: was not absent\n", obj->mm.region->name);
> -			goto out_unmap;
> -		}
> -	} else {
> -		/* ttm allows access to evicted regions by design */
> -
> -		err = check_present(addr, obj->base.size);
> -		if (err) {
> -			pr_err("%s: was not present\n", obj->mm.region->name);
> -			goto out_unmap;
> -		}
> +	err = check_absent(addr, obj->base.size);
> +	if (err) {
> +		pr_err("%s: was not absent\n", obj->mm.region->name);
> +		goto out_unmap;
>   	}
>   
>   out_unmap: