drivers/gpu/drm/i915/gt/intel_gtt.c - linux/kernel/git/bpf/bpf - Git at Google

 // SPDX-License-Identifier: MIT
 /*
  * Copyright © 2020 Intel Corporation
  */

 #include <linux/slab.h> /* fault-inject.h is not standalone! */

 #include <linux/fault-inject.h>

 #include "i915_trace.h"
 #include "intel_gt.h"
 #include "intel_gtt.h"

 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)
 {
 	unsigned int nr;

 	spin_lock_nested(&stash->lock, SINGLE_DEPTH_NESTING);

 	nr = min_t(typeof(nr), 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 stack;
 	struct page *page;

 	if (I915_SELFTEST_ONLY(should_fail(&vm->fault_attr, 1)))
 		i915_gem_shrink_all(vm->i915);

 	page = stash_pop_page(&vm->free_pages);
 	if (page)
 		return page;

 	if (!vm->pt_kmap_wc)
 		return alloc_page(gfp);

 	/* Look in our global stash of WC pages... */
 	page = stash_pop_page(&vm->i915->mm.wc_stash);
 	if (page)
 		return page;

 	/*
 	 * 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(&stack);
 	do {
 		struct page *page;

 		page = alloc_page(gfp);
 		if (unlikely(!page))
 			break;

 		stack.pages[stack.nr++] = page;
 	} while (pagevec_space(&stack));

 	if (stack.nr && !set_pages_array_wc(stack.pages, stack.nr)) {
 		page = stack.pages[--stack.nr];

 		/* Merge spare WC pages to the global stash */
 		if (stack.nr)
 			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);
 	}

 	/* Return unwanted leftovers */
 	if (unlikely(stack.nr)) {
 		WARN_ON_ONCE(set_pages_array_wb(stack.pages, stack.nr));
 		__pagevec_release(&stack);
 	}

 	return page;
 }

 static void vm_free_pages_release(struct i915_address_space *vm,
 				  bool immediate)
 {
 	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) {
 		/*
 		 * 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);

 		/*
 		 * 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 (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);
 }

 static void vm_free_page(struct i915_address_space *vm, struct page *page)
 {
 	/*
 	 * On !llc, we need to change the pages back to WB. We only do so
 	 * in bulk, so we rarely need to change the page attributes here,
 	 * but doing so requires a stop_machine() from deep inside arch/x86/mm.
 	 * To make detection of the possible sleep more likely, use an
 	 * unconditional might_sleep() for everybody.
 	 */
 	might_sleep();
 	spin_lock(&vm->free_pages.lock);
 	while (!pagevec_space(&vm->free_pages.pvec))
 		vm_free_pages_release(vm, false);
 	GEM_BUG_ON(pagevec_count(&vm->free_pages.pvec) >= PAGEVEC_SIZE);
 	pagevec_add(&vm->free_pages.pvec, page);
 	spin_unlock(&vm->free_pages.lock);
 }

 void __i915_vm_close(struct i915_address_space *vm)
 {
 	struct i915_vma *vma, *vn;

 	mutex_lock(&vm->mutex);
 	list_for_each_entry_safe(vma, vn, &vm->bound_list, vm_link) {
 		struct drm_i915_gem_object *obj = vma->obj;

 		/* Keep the obj (and hence the vma) alive as _we_ destroy it */
 		if (!kref_get_unless_zero(&obj->base.refcount))
 			continue;

 		atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
 		WARN_ON(__i915_vma_unbind(vma));
 		__i915_vma_put(vma);

 		i915_gem_object_put(obj);
 	}
 	GEM_BUG_ON(!list_empty(&vm->bound_list));
 	mutex_unlock(&vm->mutex);
 }

 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);

 	mutex_destroy(&vm->mutex);
 }

 static void __i915_vm_release(struct work_struct *work)
 {
 	struct i915_address_space *vm =
 		container_of(work, struct i915_address_space, rcu.work);

 	vm->cleanup(vm);
 	i915_address_space_fini(vm);

 	kfree(vm);
 }

 void i915_vm_release(struct kref *kref)
 {
 	struct i915_address_space *vm =
 		container_of(kref, struct i915_address_space, ref);

 	GEM_BUG_ON(i915_is_ggtt(vm));
 	trace_i915_ppgtt_release(vm);

 	queue_rcu_work(vm->i915->wq, &vm->rcu);
 }

 void i915_address_space_init(struct i915_address_space *vm, int subclass)
 {
 	kref_init(&vm->ref);
 	INIT_RCU_WORK(&vm->rcu, __i915_vm_release);
 	atomic_set(&vm->open, 1);

 	/*
 	 * The vm->mutex must be reclaim safe (for use in the shrinker).
 	 * Do a dummy acquire now under fs_reclaim so that any allocation
 	 * 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->i915, &vm->mutex);

 	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->bound_list);
 }

 void clear_pages(struct i915_vma *vma)
 {
 	GEM_BUG_ON(!vma->pages);

 	if (vma->pages != vma->obj->mm.pages) {
 		sg_free_table(vma->pages);
 		kfree(vma->pages);
 	}
 	vma->pages = NULL;

 	memset(&vma->page_sizes, 0, sizeof(vma->page_sizes));
 }

 static int __setup_page_dma(struct i915_address_space *vm,
 			    struct i915_page_dma *p,
 			    gfp_t gfp)
 {
 	p->page = vm_alloc_page(vm, gfp | I915_GFP_ALLOW_FAIL);
 	if (unlikely(!p->page))
 		return -ENOMEM;

 	p->daddr = dma_map_page_attrs(vm->dma,
 				      p->page, 0, PAGE_SIZE,
 				      PCI_DMA_BIDIRECTIONAL,
 				      DMA_ATTR_SKIP_CPU_SYNC |
 				      DMA_ATTR_NO_WARN);
 	if (unlikely(dma_mapping_error(vm->dma, p->daddr))) {
 		vm_free_page(vm, p->page);
 		return -ENOMEM;
 	}

 	return 0;
 }

 int setup_page_dma(struct i915_address_space *vm, struct i915_page_dma *p)
 {
 	return __setup_page_dma(vm, p, __GFP_HIGHMEM);
 }

 void cleanup_page_dma(struct i915_address_space *vm, struct i915_page_dma *p)
 {
 	dma_unmap_page(vm->dma, p->daddr, PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
 	vm_free_page(vm, p->page);
 }

 void
 fill_page_dma(const struct i915_page_dma *p, const u64 val, unsigned int count)
 {
 	kunmap_atomic(memset64(kmap_atomic(p->page), val, count));
 }

 int setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)
 {
 	unsigned long size;

 	/*
 	 * In order to utilize 64K pages for an object with a size < 2M, we will
 	 * need to support a 64K scratch page, given that every 16th entry for a
 	 * page-table operating in 64K mode must point to a properly aligned 64K
 	 * region, including any PTEs which happen to point to scratch.
 	 *
 	 * This is only relevant for the 48b PPGTT where we support
 	 * huge-gtt-pages, see also i915_vma_insert(). However, as we share the
 	 * scratch (read-only) between all vm, we create one 64k scratch page
 	 * for all.
 	 */
 	size = I915_GTT_PAGE_SIZE_4K;
 	if (i915_vm_is_4lvl(vm) &&
 	    HAS_PAGE_SIZES(vm->i915, I915_GTT_PAGE_SIZE_64K)) {
 		size = I915_GTT_PAGE_SIZE_64K;
 		gfp |= __GFP_NOWARN;
 	}
 	gfp |= __GFP_ZERO | __GFP_RETRY_MAYFAIL;

 	do {
 		unsigned int order = get_order(size);
 		struct page *page;
 		dma_addr_t addr;

 		page = alloc_pages(gfp, order);
 		if (unlikely(!page))
 			goto skip;

 		addr = dma_map_page_attrs(vm->dma,
 					  page, 0, size,
 					  PCI_DMA_BIDIRECTIONAL,
 					  DMA_ATTR_SKIP_CPU_SYNC |
 					  DMA_ATTR_NO_WARN);
 		if (unlikely(dma_mapping_error(vm->dma, addr)))
 			goto free_page;

 		if (unlikely(!IS_ALIGNED(addr, size)))
 			goto unmap_page;

 		vm->scratch[0].base.page = page;
 		vm->scratch[0].base.daddr = addr;
 		vm->scratch_order = order;
 		return 0;

 unmap_page:
 		dma_unmap_page(vm->dma, addr, size, PCI_DMA_BIDIRECTIONAL);
 free_page:
 		__free_pages(page, order);
 skip:
 		if (size == I915_GTT_PAGE_SIZE_4K)
 			return -ENOMEM;

 		size = I915_GTT_PAGE_SIZE_4K;
 		gfp &= ~__GFP_NOWARN;
 	} while (1);
 }

 void cleanup_scratch_page(struct i915_address_space *vm)
 {
 	struct i915_page_dma *p = px_base(&vm->scratch[0]);
 	unsigned int order = vm->scratch_order;

 	dma_unmap_page(vm->dma, p->daddr, BIT(order) << PAGE_SHIFT,
 		       PCI_DMA_BIDIRECTIONAL);
 	__free_pages(p->page, order);
 }

 void free_scratch(struct i915_address_space *vm)
 {
 	int i;

 	if (!px_dma(&vm->scratch[0])) /* set to 0 on clones */
 		return;

 	for (i = 1; i <= vm->top; i++) {
 		if (!px_dma(&vm->scratch[i]))
 			break;
 		cleanup_page_dma(vm, px_base(&vm->scratch[i]));
 	}

 	cleanup_scratch_page(vm);
 }

 void gtt_write_workarounds(struct intel_gt *gt)
 {
 	struct drm_i915_private *i915 = gt->i915;
 	struct intel_uncore *uncore = gt->uncore;

 	/*
 	 * This function is for gtt related workarounds. This function is
 	 * called on driver load and after a GPU reset, so you can place
 	 * workarounds here even if they get overwritten by GPU reset.
 	 */
 	/* WaIncreaseDefaultTLBEntries:chv,bdw,skl,bxt,kbl,glk,cfl,cnl,icl */
 	if (IS_BROADWELL(i915))
 		intel_uncore_write(uncore,
 				   GEN8_L3_LRA_1_GPGPU,
 				   GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_BDW);
 	else if (IS_CHERRYVIEW(i915))
 		intel_uncore_write(uncore,
 				   GEN8_L3_LRA_1_GPGPU,
 				   GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_CHV);
 	else if (IS_GEN9_LP(i915))
 		intel_uncore_write(uncore,
 				   GEN8_L3_LRA_1_GPGPU,
 				   GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_BXT);
 	else if (INTEL_GEN(i915) >= 9 && INTEL_GEN(i915) <= 11)
 		intel_uncore_write(uncore,
 				   GEN8_L3_LRA_1_GPGPU,
 				   GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_SKL);

 	/*
 	 * To support 64K PTEs we need to first enable the use of the
 	 * Intermediate-Page-Size(IPS) bit of the PDE field via some magical
 	 * mmio, otherwise the page-walker will simply ignore the IPS bit. This
 	 * shouldn't be needed after GEN10.
 	 *
 	 * 64K pages were first introduced from BDW+, although technically they
 	 * only *work* from gen9+. For pre-BDW we instead have the option for
 	 * 32K pages, but we don't currently have any support for it in our
 	 * driver.
 	 */
 	if (HAS_PAGE_SIZES(i915, I915_GTT_PAGE_SIZE_64K) &&
 	    INTEL_GEN(i915) <= 10)
 		intel_uncore_rmw(uncore,
 				 GEN8_GAMW_ECO_DEV_RW_IA,
 				 0,
 				 GAMW_ECO_ENABLE_64K_IPS_FIELD);

 	if (IS_GEN_RANGE(i915, 8, 11)) {
 		bool can_use_gtt_cache = true;

 		/*
 		 * According to the BSpec if we use 2M/1G pages then we also
 		 * need to disable the GTT cache. At least on BDW we can see
 		 * visual corruption when using 2M pages, and not disabling the
 		 * GTT cache.
 		 */
 		if (HAS_PAGE_SIZES(i915, I915_GTT_PAGE_SIZE_2M))
 			can_use_gtt_cache = false;

 		/* WaGttCachingOffByDefault */
 		intel_uncore_write(uncore,
 				   HSW_GTT_CACHE_EN,
 				   can_use_gtt_cache ? GTT_CACHE_EN_ALL : 0);
 		WARN_ON_ONCE(can_use_gtt_cache &&
 			     intel_uncore_read(uncore,
 					       HSW_GTT_CACHE_EN) == 0);
 	}
 }

 u64 gen8_pte_encode(dma_addr_t addr,
 		    enum i915_cache_level level,
 		    u32 flags)
 {
 	gen8_pte_t pte = addr | _PAGE_PRESENT | _PAGE_RW;

 	if (unlikely(flags & PTE_READ_ONLY))
 		pte &= ~_PAGE_RW;

 	switch (level) {
 	case I915_CACHE_NONE:
 		pte |= PPAT_UNCACHED;
 		break;
 	case I915_CACHE_WT:
 		pte |= PPAT_DISPLAY_ELLC;
 		break;
 	default:
 		pte |= PPAT_CACHED;
 		break;
 	}

 	return pte;
 }

 static void tgl_setup_private_ppat(struct intel_uncore *uncore)
 {
 	/* TGL doesn't support LLC or AGE settings */
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(0), GEN8_PPAT_WB);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(1), GEN8_PPAT_WC);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(2), GEN8_PPAT_WT);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(3), GEN8_PPAT_UC);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(4), GEN8_PPAT_WB);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(5), GEN8_PPAT_WB);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(6), GEN8_PPAT_WB);
 	intel_uncore_write(uncore, GEN12_PAT_INDEX(7), GEN8_PPAT_WB);
 }

 static void cnl_setup_private_ppat(struct intel_uncore *uncore)
 {
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(0),
 			   GEN8_PPAT_WB | GEN8_PPAT_LLC);
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(1),
 			   GEN8_PPAT_WC | GEN8_PPAT_LLCELLC);
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(2),
 			   GEN8_PPAT_WT | GEN8_PPAT_LLCELLC);
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(3),
 			   GEN8_PPAT_UC);
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(4),
 			   GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(0));
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(5),
 			   GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(1));
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(6),
 			   GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(2));
 	intel_uncore_write(uncore,
 			   GEN10_PAT_INDEX(7),
 			   GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(3));
 }

 /*
  * The GGTT and PPGTT need a private PPAT setup in order to handle cacheability
  * bits. When using advanced contexts each context stores its own PAT, but
  * writing this data shouldn't be harmful even in those cases.
  */
 static void bdw_setup_private_ppat(struct intel_uncore *uncore)
 {
 	u64 pat;

 	pat = GEN8_PPAT(0, GEN8_PPAT_WB | GEN8_PPAT_LLC) |	/* for normal objects, no eLLC */
 	      GEN8_PPAT(1, GEN8_PPAT_WC | GEN8_PPAT_LLCELLC) |	/* for something pointing to ptes? */
 	      GEN8_PPAT(2, GEN8_PPAT_WT | GEN8_PPAT_LLCELLC) |	/* for scanout with eLLC */
 	      GEN8_PPAT(3, GEN8_PPAT_UC) |			/* Uncached objects, mostly for scanout */
 	      GEN8_PPAT(4, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(0)) |
 	      GEN8_PPAT(5, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(1)) |
 	      GEN8_PPAT(6, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(2)) |
 	      GEN8_PPAT(7, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(3));

 	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_LO, lower_32_bits(pat));
 	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_HI, upper_32_bits(pat));
 }

 static void chv_setup_private_ppat(struct intel_uncore *uncore)
 {
 	u64 pat;

 	/*
 	 * Map WB on BDW to snooped on CHV.
 	 *
 	 * Only the snoop bit has meaning for CHV, the rest is
 	 * ignored.
 	 *
 	 * The hardware will never snoop for certain types of accesses:
 	 * - CPU GTT (GMADR->GGTT->no snoop->memory)
 	 * - PPGTT page tables
 	 * - some other special cycles
 	 *
 	 * As with BDW, we also need to consider the following for GT accesses:
 	 * "For GGTT, there is NO pat_sel[2:0] from the entry,
 	 * so RTL will always use the value corresponding to
 	 * pat_sel = 000".
 	 * Which means we must set the snoop bit in PAT entry 0
 	 * in order to keep the global status page working.
 	 */

 	pat = GEN8_PPAT(0, CHV_PPAT_SNOOP) |
 	      GEN8_PPAT(1, 0) |
 	      GEN8_PPAT(2, 0) |
 	      GEN8_PPAT(3, 0) |
 	      GEN8_PPAT(4, CHV_PPAT_SNOOP) |
 	      GEN8_PPAT(5, CHV_PPAT_SNOOP) |
 	      GEN8_PPAT(6, CHV_PPAT_SNOOP) |
 	      GEN8_PPAT(7, CHV_PPAT_SNOOP);

 	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_LO, lower_32_bits(pat));
 	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_HI, upper_32_bits(pat));
 }

 void setup_private_pat(struct intel_uncore *uncore)
 {
 	struct drm_i915_private *i915 = uncore->i915;

 	GEM_BUG_ON(INTEL_GEN(i915) < 8);

 	if (INTEL_GEN(i915) >= 12)
 		tgl_setup_private_ppat(uncore);
 	else if (INTEL_GEN(i915) >= 10)
 		cnl_setup_private_ppat(uncore);
 	else if (IS_CHERRYVIEW(i915) || IS_GEN9_LP(i915))
 		chv_setup_private_ppat(uncore);
 	else
 		bdw_setup_private_ppat(uncore);
 }

 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_gtt.c"
 #endif
	// SPDX-License-Identifier: MIT
	/*
	* Copyright © 2020 Intel Corporation
	*/

	#include <linux/slab.h> /* fault-inject.h is not standalone! */

	#include <linux/fault-inject.h>

	#include "i915_trace.h"
	#include "intel_gt.h"
	#include "intel_gtt.h"

	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)
	{
	unsigned int nr;

	spin_lock_nested(&stash->lock, SINGLE_DEPTH_NESTING);

	nr = min_t(typeof(nr), 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 stack;
	struct page *page;

	if (I915_SELFTEST_ONLY(should_fail(&vm->fault_attr, 1)))
	i915_gem_shrink_all(vm->i915);

	page = stash_pop_page(&vm->free_pages);
	if (page)
	return page;

	if (!vm->pt_kmap_wc)
	return alloc_page(gfp);

	/* Look in our global stash of WC pages... */
	page = stash_pop_page(&vm->i915->mm.wc_stash);
	if (page)
	return page;

	/*
	* 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(&stack);
	do {
	struct page *page;

	page = alloc_page(gfp);
	if (unlikely(!page))
	break;

	stack.pages[stack.nr++] = page;
	} while (pagevec_space(&stack));

	if (stack.nr && !set_pages_array_wc(stack.pages, stack.nr)) {
	page = stack.pages[--stack.nr];

	/* Merge spare WC pages to the global stash */
	if (stack.nr)
	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);
	}

	/* Return unwanted leftovers */
	if (unlikely(stack.nr)) {
	WARN_ON_ONCE(set_pages_array_wb(stack.pages, stack.nr));
	__pagevec_release(&stack);
	}

	return page;
	}

	static void vm_free_pages_release(struct i915_address_space *vm,
	bool immediate)
	{
	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) {
	/*
	* 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);

	/*
	* 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 (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);
	}

	static void vm_free_page(struct i915_address_space vm, struct page page)
	{
	/*
	* On !llc, we need to change the pages back to WB. We only do so
	* in bulk, so we rarely need to change the page attributes here,
	* but doing so requires a stop_machine() from deep inside arch/x86/mm.
	* To make detection of the possible sleep more likely, use an
	* unconditional might_sleep() for everybody.
	*/
	might_sleep();
	spin_lock(&vm->free_pages.lock);
	while (!pagevec_space(&vm->free_pages.pvec))
	vm_free_pages_release(vm, false);
	GEM_BUG_ON(pagevec_count(&vm->free_pages.pvec) >= PAGEVEC_SIZE);
	pagevec_add(&vm->free_pages.pvec, page);
	spin_unlock(&vm->free_pages.lock);
	}

	void __i915_vm_close(struct i915_address_space *vm)
	{
	struct i915_vma vma, vn;

	mutex_lock(&vm->mutex);
	list_for_each_entry_safe(vma, vn, &vm->bound_list, vm_link) {
	struct drm_i915_gem_object *obj = vma->obj;

	/* Keep the obj (and hence the vma) alive as _we_ destroy it */
	if (!kref_get_unless_zero(&obj->base.refcount))
	continue;

	atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
	WARN_ON(__i915_vma_unbind(vma));
	__i915_vma_put(vma);

	i915_gem_object_put(obj);
	}
	GEM_BUG_ON(!list_empty(&vm->bound_list));
	mutex_unlock(&vm->mutex);
	}

	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);

	mutex_destroy(&vm->mutex);
	}

	static void __i915_vm_release(struct work_struct *work)
	{
	struct i915_address_space *vm =
	container_of(work, struct i915_address_space, rcu.work);

	vm->cleanup(vm);
	i915_address_space_fini(vm);

	kfree(vm);
	}

	void i915_vm_release(struct kref *kref)
	{
	struct i915_address_space *vm =
	container_of(kref, struct i915_address_space, ref);

	GEM_BUG_ON(i915_is_ggtt(vm));
	trace_i915_ppgtt_release(vm);

	queue_rcu_work(vm->i915->wq, &vm->rcu);
	}

	void i915_address_space_init(struct i915_address_space *vm, int subclass)
	{
	kref_init(&vm->ref);
	INIT_RCU_WORK(&vm->rcu, __i915_vm_release);
	atomic_set(&vm->open, 1);

	/*
	* The vm->mutex must be reclaim safe (for use in the shrinker).
	* Do a dummy acquire now under fs_reclaim so that any allocation
	* 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->i915, &vm->mutex);

	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->bound_list);
	}

	void clear_pages(struct i915_vma *vma)
	{
	GEM_BUG_ON(!vma->pages);

	if (vma->pages != vma->obj->mm.pages) {
	sg_free_table(vma->pages);
	kfree(vma->pages);
	}
	vma->pages = NULL;

	memset(&vma->page_sizes, 0, sizeof(vma->page_sizes));
	}

	static int __setup_page_dma(struct i915_address_space *vm,
	struct i915_page_dma *p,
	gfp_t gfp)
	{
	p->page = vm_alloc_page(vm, gfp \| I915_GFP_ALLOW_FAIL);
	if (unlikely(!p->page))
	return -ENOMEM;

	p->daddr = dma_map_page_attrs(vm->dma,
	p->page, 0, PAGE_SIZE,
	PCI_DMA_BIDIRECTIONAL,
	DMA_ATTR_SKIP_CPU_SYNC \|
	DMA_ATTR_NO_WARN);
	if (unlikely(dma_mapping_error(vm->dma, p->daddr))) {
	vm_free_page(vm, p->page);
	return -ENOMEM;
	}

	return 0;
	}

	int setup_page_dma(struct i915_address_space vm, struct i915_page_dma p)
	{
	return __setup_page_dma(vm, p, __GFP_HIGHMEM);
	}

	void cleanup_page_dma(struct i915_address_space vm, struct i915_page_dma p)
	{
	dma_unmap_page(vm->dma, p->daddr, PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
	vm_free_page(vm, p->page);
	}

	void
	fill_page_dma(const struct i915_page_dma *p, const u64 val, unsigned int count)
	{
	kunmap_atomic(memset64(kmap_atomic(p->page), val, count));
	}

	int setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)
	{
	unsigned long size;

	/*
	* In order to utilize 64K pages for an object with a size < 2M, we will
	* need to support a 64K scratch page, given that every 16th entry for a
	* page-table operating in 64K mode must point to a properly aligned 64K
	* region, including any PTEs which happen to point to scratch.
	*
	* This is only relevant for the 48b PPGTT where we support
	* huge-gtt-pages, see also i915_vma_insert(). However, as we share the
	* scratch (read-only) between all vm, we create one 64k scratch page
	* for all.
	*/
	size = I915_GTT_PAGE_SIZE_4K;
	if (i915_vm_is_4lvl(vm) &&
	HAS_PAGE_SIZES(vm->i915, I915_GTT_PAGE_SIZE_64K)) {
	size = I915_GTT_PAGE_SIZE_64K;
	gfp \|= __GFP_NOWARN;
	}
	gfp \|= __GFP_ZERO \| __GFP_RETRY_MAYFAIL;

	do {
	unsigned int order = get_order(size);
	struct page *page;
	dma_addr_t addr;

	page = alloc_pages(gfp, order);
	if (unlikely(!page))
	goto skip;

	addr = dma_map_page_attrs(vm->dma,
	page, 0, size,
	PCI_DMA_BIDIRECTIONAL,
	DMA_ATTR_SKIP_CPU_SYNC \|
	DMA_ATTR_NO_WARN);
	if (unlikely(dma_mapping_error(vm->dma, addr)))
	goto free_page;

	if (unlikely(!IS_ALIGNED(addr, size)))
	goto unmap_page;

	vm->scratch[0].base.page = page;
	vm->scratch[0].base.daddr = addr;
	vm->scratch_order = order;
	return 0;

	unmap_page:
	dma_unmap_page(vm->dma, addr, size, PCI_DMA_BIDIRECTIONAL);
	free_page:
	__free_pages(page, order);
	skip:
	if (size == I915_GTT_PAGE_SIZE_4K)
	return -ENOMEM;

	size = I915_GTT_PAGE_SIZE_4K;
	gfp &= ~__GFP_NOWARN;
	} while (1);
	}

	void cleanup_scratch_page(struct i915_address_space *vm)
	{
	struct i915_page_dma *p = px_base(&vm->scratch[0]);
	unsigned int order = vm->scratch_order;

	dma_unmap_page(vm->dma, p->daddr, BIT(order) << PAGE_SHIFT,
	PCI_DMA_BIDIRECTIONAL);
	__free_pages(p->page, order);
	}

	void free_scratch(struct i915_address_space *vm)
	{
	int i;

	if (!px_dma(&vm->scratch[0])) /* set to 0 on clones */
	return;

	for (i = 1; i <= vm->top; i++) {
	if (!px_dma(&vm->scratch[i]))
	break;
	cleanup_page_dma(vm, px_base(&vm->scratch[i]));
	}

	cleanup_scratch_page(vm);
	}

	void gtt_write_workarounds(struct intel_gt *gt)
	{
	struct drm_i915_private *i915 = gt->i915;
	struct intel_uncore *uncore = gt->uncore;

	/*
	* This function is for gtt related workarounds. This function is
	* called on driver load and after a GPU reset, so you can place
	* workarounds here even if they get overwritten by GPU reset.
	*/
	/* WaIncreaseDefaultTLBEntries:chv,bdw,skl,bxt,kbl,glk,cfl,cnl,icl */
	if (IS_BROADWELL(i915))
	intel_uncore_write(uncore,
	GEN8_L3_LRA_1_GPGPU,
	GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_BDW);
	else if (IS_CHERRYVIEW(i915))
	intel_uncore_write(uncore,
	GEN8_L3_LRA_1_GPGPU,
	GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_CHV);
	else if (IS_GEN9_LP(i915))
	intel_uncore_write(uncore,
	GEN8_L3_LRA_1_GPGPU,
	GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_BXT);
	else if (INTEL_GEN(i915) >= 9 && INTEL_GEN(i915) <= 11)
	intel_uncore_write(uncore,
	GEN8_L3_LRA_1_GPGPU,
	GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_SKL);

	/*
	* To support 64K PTEs we need to first enable the use of the
	* Intermediate-Page-Size(IPS) bit of the PDE field via some magical
	* mmio, otherwise the page-walker will simply ignore the IPS bit. This
	* shouldn't be needed after GEN10.
	*
	* 64K pages were first introduced from BDW+, although technically they
	* only work from gen9+. For pre-BDW we instead have the option for
	* 32K pages, but we don't currently have any support for it in our
	* driver.
	*/
	if (HAS_PAGE_SIZES(i915, I915_GTT_PAGE_SIZE_64K) &&
	INTEL_GEN(i915) <= 10)
	intel_uncore_rmw(uncore,
	GEN8_GAMW_ECO_DEV_RW_IA,
	0,
	GAMW_ECO_ENABLE_64K_IPS_FIELD);

	if (IS_GEN_RANGE(i915, 8, 11)) {
	bool can_use_gtt_cache = true;

	/*
	* According to the BSpec if we use 2M/1G pages then we also
	* need to disable the GTT cache. At least on BDW we can see
	* visual corruption when using 2M pages, and not disabling the
	* GTT cache.
	*/
	if (HAS_PAGE_SIZES(i915, I915_GTT_PAGE_SIZE_2M))
	can_use_gtt_cache = false;

	/* WaGttCachingOffByDefault */
	intel_uncore_write(uncore,
	HSW_GTT_CACHE_EN,
	can_use_gtt_cache ? GTT_CACHE_EN_ALL : 0);
	WARN_ON_ONCE(can_use_gtt_cache &&
	intel_uncore_read(uncore,
	HSW_GTT_CACHE_EN) == 0);
	}
	}

	u64 gen8_pte_encode(dma_addr_t addr,
	enum i915_cache_level level,
	u32 flags)
	{
	gen8_pte_t pte = addr \| _PAGE_PRESENT \| _PAGE_RW;

	if (unlikely(flags & PTE_READ_ONLY))
	pte &= ~_PAGE_RW;

	switch (level) {
	case I915_CACHE_NONE:
	pte \|= PPAT_UNCACHED;
	break;
	case I915_CACHE_WT:
	pte \|= PPAT_DISPLAY_ELLC;
	break;
	default:
	pte \|= PPAT_CACHED;
	break;
	}

	return pte;
	}

	static void tgl_setup_private_ppat(struct intel_uncore *uncore)
	{
	/* TGL doesn't support LLC or AGE settings */
	intel_uncore_write(uncore, GEN12_PAT_INDEX(0), GEN8_PPAT_WB);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(1), GEN8_PPAT_WC);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(2), GEN8_PPAT_WT);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(3), GEN8_PPAT_UC);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(4), GEN8_PPAT_WB);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(5), GEN8_PPAT_WB);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(6), GEN8_PPAT_WB);
	intel_uncore_write(uncore, GEN12_PAT_INDEX(7), GEN8_PPAT_WB);
	}

	static void cnl_setup_private_ppat(struct intel_uncore *uncore)
	{
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(0),
	GEN8_PPAT_WB \| GEN8_PPAT_LLC);
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(1),
	GEN8_PPAT_WC \| GEN8_PPAT_LLCELLC);
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(2),
	GEN8_PPAT_WT \| GEN8_PPAT_LLCELLC);
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(3),
	GEN8_PPAT_UC);
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(4),
	GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(0));
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(5),
	GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(1));
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(6),
	GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(2));
	intel_uncore_write(uncore,
	GEN10_PAT_INDEX(7),
	GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(3));
	}

	/*
	* The GGTT and PPGTT need a private PPAT setup in order to handle cacheability
	* bits. When using advanced contexts each context stores its own PAT, but
	* writing this data shouldn't be harmful even in those cases.
	*/
	static void bdw_setup_private_ppat(struct intel_uncore *uncore)
	{
	u64 pat;

	pat = GEN8_PPAT(0, GEN8_PPAT_WB \| GEN8_PPAT_LLC) \| /* for normal objects, no eLLC */
	GEN8_PPAT(1, GEN8_PPAT_WC \| GEN8_PPAT_LLCELLC) \| /* for something pointing to ptes? */
	GEN8_PPAT(2, GEN8_PPAT_WT \| GEN8_PPAT_LLCELLC) \| /* for scanout with eLLC */
	GEN8_PPAT(3, GEN8_PPAT_UC) \| /* Uncached objects, mostly for scanout */
	GEN8_PPAT(4, GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(0)) \|
	GEN8_PPAT(5, GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(1)) \|
	GEN8_PPAT(6, GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(2)) \|
	GEN8_PPAT(7, GEN8_PPAT_WB \| GEN8_PPAT_LLCELLC \| GEN8_PPAT_AGE(3));

	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_LO, lower_32_bits(pat));
	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_HI, upper_32_bits(pat));
	}

	static void chv_setup_private_ppat(struct intel_uncore *uncore)
	{
	u64 pat;

	/*
	* Map WB on BDW to snooped on CHV.
	*
	* Only the snoop bit has meaning for CHV, the rest is
	* ignored.
	*
	* The hardware will never snoop for certain types of accesses:
	* - CPU GTT (GMADR->GGTT->no snoop->memory)
	* - PPGTT page tables
	* - some other special cycles
	*
	* As with BDW, we also need to consider the following for GT accesses:
	* "For GGTT, there is NO pat_sel[2:0] from the entry,
	* so RTL will always use the value corresponding to
	* pat_sel = 000".
	* Which means we must set the snoop bit in PAT entry 0
	* in order to keep the global status page working.
	*/

	pat = GEN8_PPAT(0, CHV_PPAT_SNOOP) \|
	GEN8_PPAT(1, 0) \|
	GEN8_PPAT(2, 0) \|
	GEN8_PPAT(3, 0) \|
	GEN8_PPAT(4, CHV_PPAT_SNOOP) \|
	GEN8_PPAT(5, CHV_PPAT_SNOOP) \|
	GEN8_PPAT(6, CHV_PPAT_SNOOP) \|
	GEN8_PPAT(7, CHV_PPAT_SNOOP);

	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_LO, lower_32_bits(pat));
	intel_uncore_write(uncore, GEN8_PRIVATE_PAT_HI, upper_32_bits(pat));
	}

	void setup_private_pat(struct intel_uncore *uncore)
	{
	struct drm_i915_private *i915 = uncore->i915;

	GEM_BUG_ON(INTEL_GEN(i915) < 8);

	if (INTEL_GEN(i915) >= 12)
	tgl_setup_private_ppat(uncore);
	else if (INTEL_GEN(i915) >= 10)
	cnl_setup_private_ppat(uncore);
	else if (IS_CHERRYVIEW(i915) \|\| IS_GEN9_LP(i915))
	chv_setup_private_ppat(uncore);
	else
	bdw_setup_private_ppat(uncore);
	}

	#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
	#include "selftests/mock_gtt.c"
	#endif