Re: [PATCH 12/21] drm/i915: Mark up address spaces that may need to allocate

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 02/09/2019 05:02, Chris Wilson wrote:
> Since we cannot allocate underneath the vm->mutex (it is used in the
> direct-reclaim paths), we need to shift the allocations off into a
> mutexless worker with fence recursion prevention. To know when we need
> this protection, we mark up the address spaces that do allocate before
> insertion.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem_gtt.c | 3 +++
>   drivers/gpu/drm/i915/i915_gem_gtt.h | 2 ++
>   2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 9095f017162e..56d27cf09a3d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -1500,6 +1500,7 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
>   			goto err_free_pd;
>   	}
>   
> +	ppgtt->vm.bind_alloc = I915_VMA_LOCAL_BIND;

So this is re-using I915_VMA_LOCAL_BIND as a trick? Is it clear how that 
works from these call sites? Should it be called bind_alloc*s*? 
bind_allocates? Or be a boolean which is converted to a trick flag in 
i915_vma_bind where a comment can be put explaining the trick?

Regards,

Tvrtko

>   	ppgtt->vm.insert_entries = gen8_ppgtt_insert;
>   	ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc;
>   	ppgtt->vm.clear_range = gen8_ppgtt_clear;
> @@ -1947,6 +1948,7 @@ static struct i915_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
>   	ppgtt_init(&ppgtt->base, &i915->gt);
>   	ppgtt->base.vm.top = 1;
>   
> +	ppgtt->base.vm.bind_alloc = I915_VMA_LOCAL_BIND;
>   	ppgtt->base.vm.allocate_va_range = gen6_alloc_va_range;
>   	ppgtt->base.vm.clear_range = gen6_ppgtt_clear_range;
>   	ppgtt->base.vm.insert_entries = gen6_ppgtt_insert_entries;
> @@ -2578,6 +2580,7 @@ static int init_aliasing_ppgtt(struct i915_ggtt *ggtt)
>   		goto err_ppgtt;
>   
>   	ggtt->alias = ppgtt;
> +	ggtt->vm.bind_alloc |= ppgtt->vm.bind_alloc;
>   
>   	GEM_BUG_ON(ggtt->vm.vma_ops.bind_vma != ggtt_bind_vma);
>   	ggtt->vm.vma_ops.bind_vma = aliasing_gtt_bind_vma;
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index 57d27898639a..007bdaf4ba00 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -305,6 +305,8 @@ struct i915_address_space {
>   	u64 total;		/* size addr space maps (ex. 2GB for ggtt) */
>   	u64 reserved;		/* size addr space reserved */
>   
> +	unsigned int bind_alloc;
> +
>   	bool closed;
>   
>   	struct mutex mutex; /* protects vma and our lists */
> 
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