Re: [PATCH 18/39] drm/i915: Differentiate between ggtt->mutex and ppgtt->mutex

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

Mika's reply here reminded me that the patch looks familiar and indeed I 
r-b-ed it back in September.

Can keep it after the blank line adjustment and ordering shuffles of course.

Not sure on the is_ggtt vs the subclass id - perhaps even it would make 
more sense to set is_ggtt before the call to i915_address_space_init and 
then inside derive the lock subclass from it. Although even that is not 
fully elegant. Maybe is_ggtt gneneric flag to i915_address_space_init to 
do both tasks?

Regards,

Tvrtko

On 02/01/2019 09:41, Chris Wilson wrote:
> We have two classes of VM, global GTT and per-process GTT. In order to
> allow ourselves the freedom to mix both along call chains, distinguish
> the two classes with regards to their mutex and lockdep maps.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem_gtt.c       | 10 +++++-----
>   drivers/gpu/drm/i915/i915_gem_gtt.h       |  2 ++
>   drivers/gpu/drm/i915/selftests/mock_gtt.c |  6 +++---
>   3 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 852dbc1f185f..8f93b1dffbb9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -474,8 +474,7 @@ static void vm_free_page(struct i915_address_space *vm, struct page *page)
>   	spin_unlock(&vm->free_pages.lock);
>   }
>   
> -static void i915_address_space_init(struct i915_address_space *vm,
> -				    struct drm_i915_private *dev_priv)
> +static void i915_address_space_init(struct i915_address_space *vm, int subclass)
>   {
>   	/*
>   	 * The vm->mutex must be reclaim safe (for use in the shrinker).
> @@ -483,6 +482,7 @@ static void i915_address_space_init(struct i915_address_space *vm,
>   	 * attempt holding the lock is immediately reported by lockdep.
>   	 */
>   	mutex_init(&vm->mutex);
> +	lockdep_set_subclass(&vm->mutex, subclass);
>   	i915_gem_shrinker_taints_mutex(&vm->mutex);
>   
>   	GEM_BUG_ON(!vm->total);
> @@ -1548,7 +1548,7 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
>   	/* From bdw, there is support for read-only pages in the PPGTT. */
>   	ppgtt->vm.has_read_only = true;
>   
> -	i915_address_space_init(&ppgtt->vm, i915);
> +	i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);
>   
>   	/* There are only few exceptions for gen >=6. chv and bxt.
>   	 * And we are not sure about the latter so play safe for now.
> @@ -1997,7 +1997,7 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
>   
>   	ppgtt->base.vm.total = I915_PDES * GEN6_PTES * I915_GTT_PAGE_SIZE;
>   
> -	i915_address_space_init(&ppgtt->base.vm, i915);
> +	i915_address_space_init(&ppgtt->base.vm, VM_CLASS_PPGTT);
>   
>   	ppgtt->base.vm.allocate_va_range = gen6_alloc_va_range;
>   	ppgtt->base.vm.clear_range = gen6_ppgtt_clear_range;
> @@ -3434,7 +3434,7 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
>   	 * and beyond the end of the GTT if we do not provide a guard.
>   	 */
>   	mutex_lock(&dev_priv->drm.struct_mutex);
> -	i915_address_space_init(&ggtt->vm, dev_priv);
> +	i915_address_space_init(&ggtt->vm, VM_CLASS_GGTT);
>   
>   	ggtt->vm.is_ggtt = true;
>   
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index e2360f16427a..9229b03d629b 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -288,6 +288,8 @@ struct i915_address_space {
>   	bool closed;
>   
>   	struct mutex mutex; /* protects vma and our lists */
> +#define VM_CLASS_GGTT 0
> +#define VM_CLASS_PPGTT 1
>   
>   	u64 scratch_pte;
>   	struct i915_page_dma scratch_page;
> diff --git a/drivers/gpu/drm/i915/selftests/mock_gtt.c b/drivers/gpu/drm/i915/selftests/mock_gtt.c
> index 6ae418c76015..976c862b3842 100644
> --- a/drivers/gpu/drm/i915/selftests/mock_gtt.c
> +++ b/drivers/gpu/drm/i915/selftests/mock_gtt.c
> @@ -70,7 +70,7 @@ mock_ppgtt(struct drm_i915_private *i915,
>   	ppgtt->vm.total = round_down(U64_MAX, PAGE_SIZE);
>   	ppgtt->vm.file = ERR_PTR(-ENODEV);
>   
> -	i915_address_space_init(&ppgtt->vm, i915);
> +	i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);
>   
>   	ppgtt->vm.clear_range = nop_clear_range;
>   	ppgtt->vm.insert_page = mock_insert_page;
> @@ -102,6 +102,7 @@ void mock_init_ggtt(struct drm_i915_private *i915)
>   	struct i915_ggtt *ggtt = &i915->ggtt;
>   
>   	ggtt->vm.i915 = i915;
> +	ggtt->vm.is_ggtt = true;
>   
>   	ggtt->gmadr = (struct resource) DEFINE_RES_MEM(0, 2048 * PAGE_SIZE);
>   	ggtt->mappable_end = resource_size(&ggtt->gmadr);
> @@ -117,9 +118,8 @@ void mock_init_ggtt(struct drm_i915_private *i915)
>   	ggtt->vm.vma_ops.set_pages   = ggtt_set_pages;
>   	ggtt->vm.vma_ops.clear_pages = clear_pages;
>   
> -	i915_address_space_init(&ggtt->vm, i915);
>   
> -	ggtt->vm.is_ggtt = true;
> +	i915_address_space_init(&ggtt->vm, VM_CLASS_GGTT);
>   }
>   
>   void mock_fini_ggtt(struct drm_i915_private *i915)
> 
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