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Commit 63fd659f authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/gtt: Pull global wc page stash under its own locking 



Currently, the wc-stash used for providing flushed WC pages ready for
constructing the page directories is assumed to be protected by the
struct_mutex. However, we want to remove this global lock and so must
install a replacement global lock for accessing the global wc-stash (the
per-vm stash continues to be guarded by the vm).

We need to push ahead on this patch due to an oversight in hastily
removing the struct_mutex guard around the igt_ppgtt_alloc selftest. No
matter, it will prove very useful (i.e. will be required) in the near
future.

v2: Restore the onstack stash so that we can drop the vm->mutex in
future across the allocation.
v3: Restore the lost pagevec_init of the onstack allocation, and repaint
function names.
v4: Reorder init so that we don't try and use i915_address_space before
it is ininitialised.

Fixes: 1f6f0023 ("drm/i915/selftests: Drop struct_mutex around lowlevel pggtt allocation")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180704185518.4193-1-chris@chris-wilson.co.uk
parent 16659bc5

drivers/gpu/drm/i915/i915_drv.h

+1 −1
Original line number Diff line number Diff line
@@ -952,7 +952,7 @@ struct i915_gem_mm { 
	/**

	 * Small stash of WC pages

	 */

	struct pagevec wc_stash;

	struct pagestash wc_stash;



	/**

	 * tmpfs instance used for shmem backed objects

drivers/gpu/drm/i915/i915_gem_context.c

+1 −1
Original line number Diff line number Diff line
@@ -374,7 +374,7 @@ i915_gem_create_context(struct drm_i915_private *dev_priv, 
	if (USES_FULL_PPGTT(dev_priv)) {

		struct i915_hw_ppgtt *ppgtt;



		ppgtt = i915_ppgtt_create(dev_priv, file_priv, ctx->name);

		ppgtt = i915_ppgtt_create(dev_priv, file_priv);

		if (IS_ERR(ppgtt)) {

			DRM_DEBUG_DRIVER("PPGTT setup failed (%ld)\n",

					 PTR_ERR(ppgtt));

drivers/gpu/drm/i915/i915_gem_gtt.c

+132 −78
Original line number Diff line number Diff line
@@ -375,37 +375,70 @@ static gen6_pte_t iris_pte_encode(dma_addr_t addr, 
	return pte;

}



static void stash_init(struct pagestash *stash)

{

	pagevec_init(&stash->pvec);

	spin_lock_init(&stash->lock);

}



static struct page *stash_pop_page(struct pagestash *stash)

{

	struct page *page = NULL;



	spin_lock(&stash->lock);

	if (likely(stash->pvec.nr))

		page = stash->pvec.pages[--stash->pvec.nr];

	spin_unlock(&stash->lock);



	return page;

}



static void stash_push_pagevec(struct pagestash *stash, struct pagevec *pvec)

{

	int nr;



	spin_lock_nested(&stash->lock, SINGLE_DEPTH_NESTING);



	nr = min_t(int, pvec->nr, pagevec_space(&stash->pvec));

	memcpy(stash->pvec.pages + stash->pvec.nr,

	       pvec->pages + pvec->nr - nr,

	       sizeof(pvec->pages[0]) * nr);

	stash->pvec.nr += nr;



	spin_unlock(&stash->lock);



	pvec->nr -= nr;

}



static struct page *vm_alloc_page(struct i915_address_space *vm, gfp_t gfp)

{

	struct pagevec *pvec = &vm->free_pages;

	struct pagevec stash;

	struct pagevec stack;

	struct page *page;



	if (I915_SELFTEST_ONLY(should_fail(&vm->fault_attr, 1)))

		i915_gem_shrink_all(vm->i915);



	if (likely(pvec->nr))

		return pvec->pages[--pvec->nr];

	page = stash_pop_page(&vm->free_pages);

	if (page)

		return page;



	if (!vm->pt_kmap_wc)

		return alloc_page(gfp);



	/* A placeholder for a specific mutex to guard the WC stash */

	lockdep_assert_held(&vm->i915->drm.struct_mutex);



	/* Look in our global stash of WC pages... */

	pvec = &vm->i915->mm.wc_stash;

	if (likely(pvec->nr))

		return pvec->pages[--pvec->nr];

	page = stash_pop_page(&vm->i915->mm.wc_stash);

	if (page)

		return page;



	/*

	 * Otherwise batch allocate pages to amoritize cost of set_pages_wc.

	 * Otherwise batch allocate pages to amortize cost of set_pages_wc.

	 *

	 * We have to be careful as page allocation may trigger the shrinker

	 * (via direct reclaim) which will fill up the WC stash underneath us.

	 * So we add our WB pages into a temporary pvec on the stack and merge

	 * them into the WC stash after all the allocations are complete.

	 */

	pagevec_init(&stash);

	pagevec_init(&stack);

	do {

		struct page *page;
@@ -413,59 +446,67 @@ static struct page *vm_alloc_page(struct i915_address_space *vm, gfp_t gfp) 
		if (unlikely(!page))

			break;



		stash.pages[stash.nr++] = page;

	} while (stash.nr < pagevec_space(pvec));

		stack.pages[stack.nr++] = page;

	} while (pagevec_space(&stack));



	if (stash.nr) {

		int nr = min_t(int, stash.nr, pagevec_space(pvec));

		struct page **pages = stash.pages + stash.nr - nr;

	if (stack.nr && !set_pages_array_wc(stack.pages, stack.nr)) {

		page = stack.pages[--stack.nr];



		if (nr && !set_pages_array_wc(pages, nr)) {

			memcpy(pvec->pages + pvec->nr,

			       pages, sizeof(pages[0]) * nr);

			pvec->nr += nr;

			stash.nr -= nr;

		/* Merge spare WC pages to the global stash */

		stash_push_pagevec(&vm->i915->mm.wc_stash, &stack);



		/* Push any surplus WC pages onto the local VM stash */

		if (stack.nr)

			stash_push_pagevec(&vm->free_pages, &stack);

	}



		pagevec_release(&stash);

	/* Return unwanted leftovers */

	if (unlikely(stack.nr)) {

		WARN_ON_ONCE(set_pages_array_wb(stack.pages, stack.nr));

		__pagevec_release(&stack);

	}



	return likely(pvec->nr) ? pvec->pages[--pvec->nr] : NULL;

	return page;

}



static void vm_free_pages_release(struct i915_address_space *vm,

				  bool immediate)

{

	struct pagevec *pvec = &vm->free_pages;

	struct pagevec *pvec = &vm->free_pages.pvec;

	struct pagevec stack;



	lockdep_assert_held(&vm->free_pages.lock);

	GEM_BUG_ON(!pagevec_count(pvec));



	if (vm->pt_kmap_wc) {

		struct pagevec *stash = &vm->i915->mm.wc_stash;



		/* When we use WC, first fill up the global stash and then

		/*

		 * When we use WC, first fill up the global stash and then

		 * only if full immediately free the overflow.

		 */

		stash_push_pagevec(&vm->i915->mm.wc_stash, pvec);



		lockdep_assert_held(&vm->i915->drm.struct_mutex);

		if (pagevec_space(stash)) {

			do {

				stash->pages[stash->nr++] =

					pvec->pages[--pvec->nr];

				if (!pvec->nr)

					return;

			} while (pagevec_space(stash));



			/* As we have made some room in the VM's free_pages,

		/*

		 * As we have made some room in the VM's free_pages,

		 * we can wait for it to fill again. Unless we are

		 * inside i915_address_space_fini() and must

		 * immediately release the pages!

		 */

			if (!immediate)

		if (pvec->nr <= (immediate ? 0 : PAGEVEC_SIZE - 1))

			return;

		}



		/*

		 * We have to drop the lock to allow ourselves to sleep,

		 * so take a copy of the pvec and clear the stash for

		 * others to use it as we sleep.

		 */

		stack = *pvec;

		pagevec_reinit(pvec);

		spin_unlock(&vm->free_pages.lock);



		pvec = &stack;

		set_pages_array_wb(pvec->pages, pvec->nr);



		spin_lock(&vm->free_pages.lock);

	}



	__pagevec_release(pvec);
@@ -481,8 +522,38 @@ static void vm_free_page(struct i915_address_space *vm, struct page *page) 
	 * unconditional might_sleep() for everybody.

	 */

	might_sleep();

	if (!pagevec_add(&vm->free_pages, page))

	spin_lock(&vm->free_pages.lock);

	if (!pagevec_add(&vm->free_pages.pvec, page))

		vm_free_pages_release(vm, false);

	spin_unlock(&vm->free_pages.lock);

}



static void i915_address_space_init(struct i915_address_space *vm,

				    struct drm_i915_private *dev_priv)

{

	GEM_BUG_ON(!vm->total);

	drm_mm_init(&vm->mm, 0, vm->total);

	vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;



	stash_init(&vm->free_pages);



	INIT_LIST_HEAD(&vm->active_list);

	INIT_LIST_HEAD(&vm->inactive_list);

	INIT_LIST_HEAD(&vm->unbound_list);



	list_add_tail(&vm->global_link, &dev_priv->vm_list);

}



static void i915_address_space_fini(struct i915_address_space *vm)

{

	spin_lock(&vm->free_pages.lock);

	if (pagevec_count(&vm->free_pages.pvec))

		vm_free_pages_release(vm, true);

	GEM_BUG_ON(pagevec_count(&vm->free_pages.pvec));

	spin_unlock(&vm->free_pages.lock);



	drm_mm_takedown(&vm->mm);

	list_del(&vm->global_link);

}



static int __setup_page_dma(struct i915_address_space *vm,
@@ -1562,6 +1633,8 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915) 
	if (!ppgtt)

		return ERR_PTR(-ENOMEM);



	kref_init(&ppgtt->ref);



	ppgtt->vm.i915 = i915;

	ppgtt->vm.dma = &i915->drm.pdev->dev;
@@ -1569,6 +1642,8 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915) 
		1ULL << 48 :

		1ULL << 32;



	i915_address_space_init(&ppgtt->vm, i915);



	/* There are only few exceptions for gen >=6. chv and bxt.

	 * And we are not sure about the latter so play safe for now.

	 */
@@ -2068,11 +2143,15 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915) 
	if (!ppgtt)

		return ERR_PTR(-ENOMEM);



	kref_init(&ppgtt->base.ref);



	ppgtt->base.vm.i915 = i915;

	ppgtt->base.vm.dma = &i915->drm.pdev->dev;



	ppgtt->base.vm.total = I915_PDES * GEN6_PTES * PAGE_SIZE;



	i915_address_space_init(&ppgtt->base.vm, i915);



	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;
@@ -2105,30 +2184,6 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915) 
	return ERR_PTR(err);

}



static void i915_address_space_init(struct i915_address_space *vm,

				    struct drm_i915_private *dev_priv,

				    const char *name)

{

	drm_mm_init(&vm->mm, 0, vm->total);

	vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;



	INIT_LIST_HEAD(&vm->active_list);

	INIT_LIST_HEAD(&vm->inactive_list);

	INIT_LIST_HEAD(&vm->unbound_list);



	list_add_tail(&vm->global_link, &dev_priv->vm_list);

	pagevec_init(&vm->free_pages);

}



static void i915_address_space_fini(struct i915_address_space *vm)

{

	if (pagevec_count(&vm->free_pages))

		vm_free_pages_release(vm, true);



	drm_mm_takedown(&vm->mm);

	list_del(&vm->global_link);

}



static void gtt_write_workarounds(struct drm_i915_private *dev_priv)

{

	/* This function is for gtt related workarounds. This function is
@@ -2199,8 +2254,7 @@ __hw_ppgtt_create(struct drm_i915_private *i915) 


struct i915_hw_ppgtt *

i915_ppgtt_create(struct drm_i915_private *i915,

		  struct drm_i915_file_private *fpriv,

		  const char *name)

		  struct drm_i915_file_private *fpriv)

{

	struct i915_hw_ppgtt *ppgtt;
@@ -2208,8 +2262,6 @@ i915_ppgtt_create(struct drm_i915_private *i915, 
	if (IS_ERR(ppgtt))

		return ppgtt;



	kref_init(&ppgtt->ref);

	i915_address_space_init(&ppgtt->vm, i915, name);

	ppgtt->vm.file = fpriv;



	trace_i915_ppgtt_create(&ppgtt->vm);
@@ -2788,7 +2840,7 @@ int i915_gem_init_aliasing_ppgtt(struct drm_i915_private *i915) 
	struct i915_hw_ppgtt *ppgtt;

	int err;



	ppgtt = i915_ppgtt_create(i915, ERR_PTR(-EPERM), "[alias]");

	ppgtt = i915_ppgtt_create(i915, ERR_PTR(-EPERM));

	if (IS_ERR(ppgtt))

		return PTR_ERR(ppgtt);
@@ -2918,7 +2970,7 @@ void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv) 


	ggtt->vm.cleanup(&ggtt->vm);



	pvec = &dev_priv->mm.wc_stash;

	pvec = &dev_priv->mm.wc_stash.pvec;

	if (pvec->nr) {

		set_pages_array_wb(pvec->pages, pvec->nr);

		__pagevec_release(pvec);
@@ -3518,6 +3570,8 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv) 
	struct i915_ggtt *ggtt = &dev_priv->ggtt;

	int ret;



	stash_init(&dev_priv->mm.wc_stash);



	INIT_LIST_HEAD(&dev_priv->vm_list);



	/* Note that we use page colouring to enforce a guard page at the
@@ -3526,7 +3580,7 @@ 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, "[global]");

	i915_address_space_init(&ggtt->vm, dev_priv);

	if (!HAS_LLC(dev_priv) && !USES_PPGTT(dev_priv))

		ggtt->vm.mm.color_adjust = i915_gtt_color_adjust;

	mutex_unlock(&dev_priv->drm.struct_mutex);

drivers/gpu/drm/i915/i915_gem_gtt.h

+7 −3
Original line number Diff line number Diff line
@@ -270,6 +270,11 @@ struct i915_vma_ops { 
	void (*clear_pages)(struct i915_vma *vma);

};



struct pagestash {

	spinlock_t lock;

	struct pagevec pvec;

};



struct i915_address_space {

	struct drm_mm mm;

	struct drm_i915_private *i915;
@@ -324,7 +329,7 @@ struct i915_address_space { 
	 */

	struct list_head unbound_list;



	struct pagevec free_pages;

	struct pagestash free_pages;

	bool pt_kmap_wc;



	/* FIXME: Need a more generic return type */
@@ -615,8 +620,7 @@ void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv); 
int i915_ppgtt_init_hw(struct drm_i915_private *dev_priv);

void i915_ppgtt_release(struct kref *kref);

struct i915_hw_ppgtt *i915_ppgtt_create(struct drm_i915_private *dev_priv,

					struct drm_i915_file_private *fpriv,

					const char *name);

					struct drm_i915_file_private *fpriv);

void i915_ppgtt_close(struct i915_address_space *vm);

static inline void i915_ppgtt_get(struct i915_hw_ppgtt *ppgtt)

{

drivers/gpu/drm/i915/selftests/huge_pages.c

+1 −1
Original line number Diff line number Diff line
@@ -1694,7 +1694,7 @@ int i915_gem_huge_page_mock_selftests(void) 
	dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(39));



	mutex_lock(&dev_priv->drm.struct_mutex);

	ppgtt = i915_ppgtt_create(dev_priv, ERR_PTR(-ENODEV), "mock");

	ppgtt = i915_ppgtt_create(dev_priv, ERR_PTR(-ENODEV));

	if (IS_ERR(ppgtt)) {

		err = PTR_ERR(ppgtt);

		goto out_unlock;