Re: [PATCH 1/4] drm/i915/gtt: Recursive cleanup for gen8

[Abdiel Janulgue <abdiel.janulgue@linux.intel.com>]

On 12/07/2019 14.27, Chris Wilson wrote:
> With an explicit level, we can refactor the separate cleanup functions
> as a simple recursive function. We take the opportunity to pass down the
> size of each level so that we can deal with the different sizes of
> top-level and avoid over allocating for 32/36-bit vm.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---

Reviewed-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>

Regards,
Abdiel


>  drivers/gpu/drm/i915/i915_gem_gtt.c | 93 ++++++++++-------------------
>  drivers/gpu/drm/i915/i915_gem_gtt.h |  2 +-
>  2 files changed, 33 insertions(+), 62 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 753090a7729e..305c65c08a6a 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -713,11 +713,11 @@ static struct i915_page_table *alloc_pt(struct i915_address_space *vm)
>  	return pt;
>  }
>  
> -static struct i915_page_directory *__alloc_pd(void)
> +static struct i915_page_directory *__alloc_pd(size_t sz)
>  {
>  	struct i915_page_directory *pd;
>  
> -	pd = kzalloc(sizeof(*pd), I915_GFP_ALLOW_FAIL);
> +	pd = kzalloc(sz, I915_GFP_ALLOW_FAIL);
>  	if (unlikely(!pd))
>  		return NULL;
>  
> @@ -729,7 +729,7 @@ static struct i915_page_directory *alloc_pd(struct i915_address_space *vm)
>  {
>  	struct i915_page_directory *pd;
>  
> -	pd = __alloc_pd();
> +	pd = __alloc_pd(sizeof(*pd));
>  	if (unlikely(!pd))
>  		return ERR_PTR(-ENOMEM);
>  
> @@ -766,7 +766,7 @@ __set_pd_entry(struct i915_page_directory * const pd,
>  	       struct i915_page_dma * const to,
>  	       u64 (*encode)(const dma_addr_t, const enum i915_cache_level))
>  {
> -	GEM_BUG_ON(atomic_read(px_used(pd)) > 512);
> +	GEM_BUG_ON(atomic_read(px_used(pd)) > ARRAY_SIZE(pd->entry));
>  
>  	atomic_inc(px_used(pd));
>  	pd->entry[idx] = to;
> @@ -896,64 +896,34 @@ static inline unsigned int gen8_pt_count(u64 start, u64 end)
>  		return end - start;
>  }
>  
> -static void gen8_free_page_tables(struct i915_address_space *vm,
> -				  struct i915_page_directory *pd)
> +static void __gen8_ppgtt_cleanup(struct i915_address_space *vm,
> +				 struct i915_page_directory *pd,
> +				 int count, int lvl)
>  {
> -	int i;
> -
> -	for (i = 0; i < I915_PDES; i++) {
> -		if (pd->entry[i])
> -			free_pd(vm, pd->entry[i]);
> -	}
> -}
> -
> -static void gen8_ppgtt_cleanup_3lvl(struct i915_address_space *vm,
> -				    struct i915_page_directory *pdp)
> -{
> -	const unsigned int pdpes = i915_pdpes_per_pdp(vm);
> -	int i;
> -
> -	for (i = 0; i < pdpes; i++) {
> -		if (!pdp->entry[i])
> -			continue;
> -
> -		gen8_free_page_tables(vm, pdp->entry[i]);
> -		free_pd(vm, pdp->entry[i]);
> -	}
> -
> -	free_px(vm, pdp);
> -}
> -
> -static void gen8_ppgtt_cleanup_4lvl(struct i915_ppgtt *ppgtt)
> -{
> -	struct i915_page_directory * const pml4 = ppgtt->pd;
> -	int i;
> -
> -	for (i = 0; i < GEN8_PML4ES_PER_PML4; i++) {
> -		struct i915_page_directory *pdp = i915_pdp_entry(pml4, i);
> +	if (lvl) {
> +		void **pde = pd->entry;
>  
> -		if (!pdp)
> -			continue;
> +		do {
> +			if (!*pde)
> +				continue;
>  
> -		gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, pdp);
> +			__gen8_ppgtt_cleanup(vm, *pde, I915_PDES, lvl - 1);
> +		} while (pde++, --count);
>  	}
>  
> -	free_px(&ppgtt->vm, pml4);
> +	free_px(vm, pd);
>  }
>  
>  static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
>  {
> -	struct drm_i915_private *i915 = vm->i915;
>  	struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
>  
> -	if (intel_vgpu_active(i915))
> +	if (intel_vgpu_active(vm->i915))
>  		gen8_ppgtt_notify_vgt(ppgtt, false);
>  
> -	if (i915_vm_is_4lvl(vm))
> -		gen8_ppgtt_cleanup_4lvl(ppgtt);
> -	else
> -		gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, ppgtt->pd);
> -
> +	__gen8_ppgtt_cleanup(vm, ppgtt->pd,
> +			     vm->total >> __gen8_pte_shift(vm->top),
> +			     vm->top);
>  	free_scratch(vm);
>  }
>  
> @@ -1505,24 +1475,18 @@ static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
>  	struct i915_page_directory *pdp = ppgtt->pd;
>  	struct i915_page_directory *pd;
>  	u64 start = 0, length = ppgtt->vm.total;
> -	u64 from = start;
>  	unsigned int pdpe;
>  
>  	gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
>  		pd = alloc_pd(vm);
>  		if (IS_ERR(pd))
> -			goto unwind;
> +			return PTR_ERR(pd);
>  
>  		fill_px(pd, vm->scratch[1].encode);
>  		set_pd_entry(pdp, pdpe, pd);
>  	}
>  
>  	return 0;
> -
> -unwind:
> -	gen8_ppgtt_clear_pdp(vm, pdp, from, start - from);
> -	atomic_set(px_used(pdp), 0);
> -	return -ENOMEM;
>  }
>  
>  static void ppgtt_init(struct i915_ppgtt *ppgtt, struct intel_gt *gt)
> @@ -1550,9 +1514,14 @@ gen8_alloc_top_pd(struct i915_address_space *vm)
>  
>  	GEM_BUG_ON(count > ARRAY_SIZE(pd->entry));
>  
> -	pd = alloc_pd(vm);
> -	if (IS_ERR(pd))
> -		return pd;
> +	pd = __alloc_pd(offsetof(typeof(*pd), entry[count]));
> +	if (unlikely(!pd))
> +		return ERR_PTR(-ENOMEM);
> +
> +	if (unlikely(setup_page_dma(vm, px_base(pd)))) {
> +		kfree(pd);
> +		return ERR_PTR(-ENOMEM);
> +	}
>  
>  	fill_page_dma(px_base(pd), vm->scratch[vm->top].encode, count);
>  	return pd;
> @@ -1625,7 +1594,9 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
>  	return ppgtt;
>  
>  err_free_pd:
> -	free_px(&ppgtt->vm, ppgtt->pd);
> +	__gen8_ppgtt_cleanup(&ppgtt->vm, ppgtt->pd,
> +			     ppgtt->vm.total >> __gen8_pte_shift(ppgtt->vm.top),
> +			     ppgtt->vm.top);
>  err_free_scratch:
>  	free_scratch(&ppgtt->vm);
>  err_free:
> @@ -2071,7 +2042,7 @@ static struct i915_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
>  
>  	ppgtt->base.vm.pte_encode = ggtt->vm.pte_encode;
>  
> -	ppgtt->base.pd = __alloc_pd();
> +	ppgtt->base.pd = __alloc_pd(sizeof(*ppgtt->base.pd));
>  	if (!ppgtt->base.pd) {
>  		err = -ENOMEM;
>  		goto err_free;
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index b30ffe333852..aea9a7084414 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -252,7 +252,7 @@ struct i915_page_table {
>  struct i915_page_directory {
>  	struct i915_page_table pt;
>  	spinlock_t lock;
> -	void *entry[512];
> +	void *entry[I915_PDES];
>  };
>  
>  #define __px_choose_expr(x, type, expr, other) \
> 
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