1 files changed, 724 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
new file mode 100644
index 000000000000..4d1de2d97d5c
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
@@ -0,0 +1,724 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#include <linux/log2.h>
+
+#include "gen8_ppgtt.h"
+#include "i915_scatterlist.h"
+#include "i915_trace.h"
+#include "i915_vgpu.h"
+#include "intel_gt.h"
+#include "intel_gtt.h"
+
+static u64 gen8_pde_encode(const dma_addr_t addr,
+			   const enum i915_cache_level level)
+{
+	u64 pde = addr | _PAGE_PRESENT | _PAGE_RW;
+
+	if (level != I915_CACHE_NONE)
+		pde |= PPAT_CACHED_PDE;
+	else
+		pde |= PPAT_UNCACHED;
+
+	return pde;
+}
+
+static void gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
+{
+	struct drm_i915_private *i915 = ppgtt->vm.i915;
+	struct intel_uncore *uncore = ppgtt->vm.gt->uncore;
+	enum vgt_g2v_type msg;
+	int i;
+
+	if (create)
+		atomic_inc(px_used(ppgtt->pd)); /* never remove */
+	else
+		atomic_dec(px_used(ppgtt->pd));
+
+	mutex_lock(&i915->vgpu.lock);
+
+	if (i915_vm_is_4lvl(&ppgtt->vm)) {
+		const u64 daddr = px_dma(ppgtt->pd);
+
+		intel_uncore_write(uncore,
+				   vgtif_reg(pdp[0].lo), lower_32_bits(daddr));
+		intel_uncore_write(uncore,
+				   vgtif_reg(pdp[0].hi), upper_32_bits(daddr));
+
+		msg = create ?
+			VGT_G2V_PPGTT_L4_PAGE_TABLE_CREATE :
+			VGT_G2V_PPGTT_L4_PAGE_TABLE_DESTROY;
+	} else {
+		for (i = 0; i < GEN8_3LVL_PDPES; i++) {
+			const u64 daddr = i915_page_dir_dma_addr(ppgtt, i);
+
+			intel_uncore_write(uncore,
+					   vgtif_reg(pdp[i].lo),
+					   lower_32_bits(daddr));
+			intel_uncore_write(uncore,
+					   vgtif_reg(pdp[i].hi),
+					   upper_32_bits(daddr));
+		}
+
+		msg = create ?
+			VGT_G2V_PPGTT_L3_PAGE_TABLE_CREATE :
+			VGT_G2V_PPGTT_L3_PAGE_TABLE_DESTROY;
+	}
+
+	/* g2v_notify atomically (via hv trap) consumes the message packet. */
+	intel_uncore_write(uncore, vgtif_reg(g2v_notify), msg);
+
+	mutex_unlock(&i915->vgpu.lock);
+}
+
+/* Index shifts into the pagetable are offset by GEN8_PTE_SHIFT [12] */
+#define GEN8_PAGE_SIZE (SZ_4K) /* page and page-directory sizes are the same */
+#define GEN8_PTE_SHIFT (ilog2(GEN8_PAGE_SIZE))
+#define GEN8_PDES (GEN8_PAGE_SIZE / sizeof(u64))
+#define gen8_pd_shift(lvl) ((lvl) * ilog2(GEN8_PDES))
+#define gen8_pd_index(i, lvl) i915_pde_index((i), gen8_pd_shift(lvl))
+#define __gen8_pte_shift(lvl) (GEN8_PTE_SHIFT + gen8_pd_shift(lvl))
+#define __gen8_pte_index(a, lvl) i915_pde_index((a), __gen8_pte_shift(lvl))
+
+#define as_pd(x) container_of((x), typeof(struct i915_page_directory), pt)
+
+static inline unsigned int
+gen8_pd_range(u64 start, u64 end, int lvl, unsigned int *idx)
+{
+	const int shift = gen8_pd_shift(lvl);
+	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
+
+	GEM_BUG_ON(start >= end);
+	end += ~mask >> gen8_pd_shift(1);
+
+	*idx = i915_pde_index(start, shift);
+	if ((start ^ end) & mask)
+		return GEN8_PDES - *idx;
+	else
+		return i915_pde_index(end, shift) - *idx;
+}
+
+static inline bool gen8_pd_contains(u64 start, u64 end, int lvl)
+{
+	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
+
+	GEM_BUG_ON(start >= end);
+	return (start ^ end) & mask && (start & ~mask) == 0;
+}
+
+static inline unsigned int gen8_pt_count(u64 start, u64 end)
+{
+	GEM_BUG_ON(start >= end);
+	if ((start ^ end) >> gen8_pd_shift(1))
+		return GEN8_PDES - (start & (GEN8_PDES - 1));
+	else
+		return end - start;
+}
+
+static inline unsigned int
+gen8_pd_top_count(const struct i915_address_space *vm)
+{
+	unsigned int shift = __gen8_pte_shift(vm->top);
+	return (vm->total + (1ull << shift) - 1) >> shift;
+}
+
+static inline struct i915_page_directory *
+gen8_pdp_for_page_index(struct i915_address_space * const vm, const u64 idx)
+{
+	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(vm);
+
+	if (vm->top == 2)
+		return ppgtt->pd;
+	else
+		return i915_pd_entry(ppgtt->pd, gen8_pd_index(idx, vm->top));
+}
+
+static inline struct i915_page_directory *
+gen8_pdp_for_page_address(struct i915_address_space * const vm, const u64 addr)
+{
+	return gen8_pdp_for_page_index(vm, addr >> GEN8_PTE_SHIFT);
+}
+
+static void __gen8_ppgtt_cleanup(struct i915_address_space *vm,
+				 struct i915_page_directory *pd,
+				 int count, int lvl)
+{
+	if (lvl) {
+		void **pde = pd->entry;
+
+		do {
+			if (!*pde)
+				continue;
+
+			__gen8_ppgtt_cleanup(vm, *pde, GEN8_PDES, lvl - 1);
+		} while (pde++, --count);
+	}
+
+	free_px(vm, pd);
+}
+
+static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
+{
+	struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
+
+	if (intel_vgpu_active(vm->i915))
+		gen8_ppgtt_notify_vgt(ppgtt, false);
+
+	__gen8_ppgtt_cleanup(vm, ppgtt->pd, gen8_pd_top_count(vm), vm->top);
+	free_scratch(vm);
+}
+
+static u64 __gen8_ppgtt_clear(struct i915_address_space * const vm,
+			      struct i915_page_directory * const pd,
+			      u64 start, const u64 end, int lvl)
+{
+	const struct i915_page_scratch * const scratch = &vm->scratch[lvl];
+	unsigned int idx, len;
+
+	GEM_BUG_ON(end > vm->total >> GEN8_PTE_SHIFT);
+
+	len = gen8_pd_range(start, end, lvl--, &idx);
+	DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d }\n",
+	    __func__, vm, lvl + 1, start, end,
+	    idx, len, atomic_read(px_used(pd)));
+	GEM_BUG_ON(!len || len >= atomic_read(px_used(pd)));
+
+	do {
+		struct i915_page_table *pt = pd->entry[idx];
+
+		if (atomic_fetch_inc(&pt->used) >> gen8_pd_shift(1) &&
+		    gen8_pd_contains(start, end, lvl)) {
+			DBG("%s(%p):{ lvl:%d, idx:%d, start:%llx, end:%llx } removing pd\n",
+			    __func__, vm, lvl + 1, idx, start, end);
+			clear_pd_entry(pd, idx, scratch);
+			__gen8_ppgtt_cleanup(vm, as_pd(pt), I915_PDES, lvl);
+			start += (u64)I915_PDES << gen8_pd_shift(lvl);
+			continue;
+		}
+
+		if (lvl) {
+			start = __gen8_ppgtt_clear(vm, as_pd(pt),
+						   start, end, lvl);
+		} else {
+			unsigned int count;
+			u64 *vaddr;
+
+			count = gen8_pt_count(start, end);
+			DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d } removing pte\n",
+			    __func__, vm, lvl, start, end,
+			    gen8_pd_index(start, 0), count,
+			    atomic_read(&pt->used));
+			GEM_BUG_ON(!count || count >= atomic_read(&pt->used));
+
+			vaddr = kmap_atomic_px(pt);
+			memset64(vaddr + gen8_pd_index(start, 0),
+				 vm->scratch[0].encode,
+				 count);
+			kunmap_atomic(vaddr);
+
+			atomic_sub(count, &pt->used);
+			start += count;
+		}
+
+		if (release_pd_entry(pd, idx, pt, scratch))
+			free_px(vm, pt);
+	} while (idx++, --len);
+
+	return start;
+}
+
+static void gen8_ppgtt_clear(struct i915_address_space *vm,
+			     u64 start, u64 length)
+{
+	GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
+	GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
+	GEM_BUG_ON(range_overflows(start, length, vm->total));
+
+	start >>= GEN8_PTE_SHIFT;
+	length >>= GEN8_PTE_SHIFT;
+	GEM_BUG_ON(length == 0);
+
+	__gen8_ppgtt_clear(vm, i915_vm_to_ppgtt(vm)->pd,
+			   start, start + length, vm->top);
+}
+
+static int __gen8_ppgtt_alloc(struct i915_address_space * const vm,
+			      struct i915_page_directory * const pd,
+			      u64 * const start, const u64 end, int lvl)
+{
+	const struct i915_page_scratch * const scratch = &vm->scratch[lvl];
+	struct i915_page_table *alloc = NULL;
+	unsigned int idx, len;
+	int ret = 0;
+
+	GEM_BUG_ON(end > vm->total >> GEN8_PTE_SHIFT);
+
+	len = gen8_pd_range(*start, end, lvl--, &idx);
+	DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d }\n",
+	    __func__, vm, lvl + 1, *start, end,
+	    idx, len, atomic_read(px_used(pd)));
+	GEM_BUG_ON(!len || (idx + len - 1) >> gen8_pd_shift(1));
+
+	spin_lock(&pd->lock);
+	GEM_BUG_ON(!atomic_read(px_used(pd))); /* Must be pinned! */
+	do {
+		struct i915_page_table *pt = pd->entry[idx];
+
+		if (!pt) {
+			spin_unlock(&pd->lock);
+
+			DBG("%s(%p):{ lvl:%d, idx:%d } allocating new tree\n",
+			    __func__, vm, lvl + 1, idx);
+
+			pt = fetch_and_zero(&alloc);
+			if (lvl) {
+				if (!pt) {
+					pt = &alloc_pd(vm)->pt;
+					if (IS_ERR(pt)) {
+						ret = PTR_ERR(pt);
+						goto out;
+					}
+				}
+
+				fill_px(pt, vm->scratch[lvl].encode);
+			} else {
+				if (!pt) {
+					pt = alloc_pt(vm);
+					if (IS_ERR(pt)) {
+						ret = PTR_ERR(pt);
+						goto out;
+					}
+				}
+
+				if (intel_vgpu_active(vm->i915) ||
+				    gen8_pt_count(*start, end) < I915_PDES)
+					fill_px(pt, vm->scratch[lvl].encode);
+			}
+
+			spin_lock(&pd->lock);
+			if (likely(!pd->entry[idx]))
+				set_pd_entry(pd, idx, pt);
+			else
+				alloc = pt, pt = pd->entry[idx];
+		}
+
+		if (lvl) {
+			atomic_inc(&pt->used);
+			spin_unlock(&pd->lock);
+
+			ret = __gen8_ppgtt_alloc(vm, as_pd(pt),
+						 start, end, lvl);
+			if (unlikely(ret)) {
+				if (release_pd_entry(pd, idx, pt, scratch))
+					free_px(vm, pt);
+				goto out;
+			}
+
+			spin_lock(&pd->lock);
+			atomic_dec(&pt->used);
+			GEM_BUG_ON(!atomic_read(&pt->used));
+		} else {
+			unsigned int count = gen8_pt_count(*start, end);
+
+			DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d } inserting pte\n",
+			    __func__, vm, lvl, *start, end,
+			    gen8_pd_index(*start, 0), count,
+			    atomic_read(&pt->used));
+
+			atomic_add(count, &pt->used);
+			/* All other pdes may be simultaneously removed */
+			GEM_BUG_ON(atomic_read(&pt->used) > NALLOC * I915_PDES);
+			*start += count;
+		}
+	} while (idx++, --len);
+	spin_unlock(&pd->lock);
+out:
+	if (alloc)
+		free_px(vm, alloc);
+	return ret;
+}
+
+static int gen8_ppgtt_alloc(struct i915_address_space *vm,
+			    u64 start, u64 length)
+{
+	u64 from;
+	int err;
+
+	GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
+	GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
+	GEM_BUG_ON(range_overflows(start, length, vm->total));
+
+	start >>= GEN8_PTE_SHIFT;
+	length >>= GEN8_PTE_SHIFT;
+	GEM_BUG_ON(length == 0);
+	from = start;
+
+	err = __gen8_ppgtt_alloc(vm, i915_vm_to_ppgtt(vm)->pd,
+				 &start, start + length, vm->top);
+	if (unlikely(err && from != start))
+		__gen8_ppgtt_clear(vm, i915_vm_to_ppgtt(vm)->pd,
+				   from, start, vm->top);
+
+	return err;
+}
+
+static __always_inline u64
+gen8_ppgtt_insert_pte(struct i915_ppgtt *ppgtt,
+		      struct i915_page_directory *pdp,
+		      struct sgt_dma *iter,
+		      u64 idx,
+		      enum i915_cache_level cache_level,
+		      u32 flags)
+{
+	struct i915_page_directory *pd;
+	const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
+	gen8_pte_t *vaddr;
+
+	pd = i915_pd_entry(pdp, gen8_pd_index(idx, 2));
+	vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
+	do {
+		GEM_BUG_ON(iter->sg->length < I915_GTT_PAGE_SIZE);
+		vaddr[gen8_pd_index(idx, 0)] = pte_encode | iter->dma;
+
+		iter->dma += I915_GTT_PAGE_SIZE;
+		if (iter->dma >= iter->max) {
+			iter->sg = __sg_next(iter->sg);
+			if (!iter->sg) {
+				idx = 0;
+				break;
+			}
+
+			iter->dma = sg_dma_address(iter->sg);
+			iter->max = iter->dma + iter->sg->length;
+		}
+
+		if (gen8_pd_index(++idx, 0) == 0) {
+			if (gen8_pd_index(idx, 1) == 0) {
+				/* Limited by sg length for 3lvl */
+				if (gen8_pd_index(idx, 2) == 0)
+					break;
+
+				pd = pdp->entry[gen8_pd_index(idx, 2)];
+			}
+
+			kunmap_atomic(vaddr);
+			vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
+		}
+	} while (1);
+	kunmap_atomic(vaddr);
+
+	return idx;
+}
+
+static void gen8_ppgtt_insert_huge(struct i915_vma *vma,
+				   struct sgt_dma *iter,
+				   enum i915_cache_level cache_level,
+				   u32 flags)
+{
+	const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
+	u64 start = vma->node.start;
+	dma_addr_t rem = iter->sg->length;
+
+	GEM_BUG_ON(!i915_vm_is_4lvl(vma->vm));
+
+	do {
+		struct i915_page_directory * const pdp =
+			gen8_pdp_for_page_address(vma->vm, start);
+		struct i915_page_directory * const pd =
+			i915_pd_entry(pdp, __gen8_pte_index(start, 2));
+		gen8_pte_t encode = pte_encode;
+		unsigned int maybe_64K = -1;
+		unsigned int page_size;
+		gen8_pte_t *vaddr;
+		u16 index;
+
+		if (vma->page_sizes.sg & I915_GTT_PAGE_SIZE_2M &&
+		    IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_2M) &&
+		    rem >= I915_GTT_PAGE_SIZE_2M &&
+		    !__gen8_pte_index(start, 0)) {
+			index = __gen8_pte_index(start, 1);
+			encode |= GEN8_PDE_PS_2M;
+			page_size = I915_GTT_PAGE_SIZE_2M;
+
+			vaddr = kmap_atomic_px(pd);
+		} else {
+			struct i915_page_table *pt =
+				i915_pt_entry(pd, __gen8_pte_index(start, 1));
+
+			index = __gen8_pte_index(start, 0);
+			page_size = I915_GTT_PAGE_SIZE;
+
+			if (!index &&
+			    vma->page_sizes.sg & I915_GTT_PAGE_SIZE_64K &&
+			    IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
+			    (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
+			     rem >= (I915_PDES - index) * I915_GTT_PAGE_SIZE))
+				maybe_64K = __gen8_pte_index(start, 1);
+
+			vaddr = kmap_atomic_px(pt);
+		}
+
+		do {
+			GEM_BUG_ON(iter->sg->length < page_size);
+			vaddr[index++] = encode | iter->dma;
+
+			start += page_size;
+			iter->dma += page_size;
+			rem -= page_size;
+			if (iter->dma >= iter->max) {
+				iter->sg = __sg_next(iter->sg);
+				if (!iter->sg)
+					break;
+
+				rem = iter->sg->length;
+				iter->dma = sg_dma_address(iter->sg);
+				iter->max = iter->dma + rem;
+
+				if (maybe_64K != -1 && index < I915_PDES &&
+				    !(IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
+				      (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
+				       rem >= (I915_PDES - index) * I915_GTT_PAGE_SIZE)))
+					maybe_64K = -1;
+
+				if (unlikely(!IS_ALIGNED(iter->dma, page_size)))
+					break;
+			}
+		} while (rem >= page_size && index < I915_PDES);
+
+		kunmap_atomic(vaddr);
+
+		/*
+		 * Is it safe to mark the 2M block as 64K? -- Either we have
+		 * filled whole page-table with 64K entries, or filled part of
+		 * it and have reached the end of the sg table and we have
+		 * enough padding.
+		 */
+		if (maybe_64K != -1 &&
+		    (index == I915_PDES ||
+		     (i915_vm_has_scratch_64K(vma->vm) &&
+		      !iter->sg && IS_ALIGNED(vma->node.start +
+					      vma->node.size,
+					      I915_GTT_PAGE_SIZE_2M)))) {
+			vaddr = kmap_atomic_px(pd);
+			vaddr[maybe_64K] |= GEN8_PDE_IPS_64K;
+			kunmap_atomic(vaddr);
+			page_size = I915_GTT_PAGE_SIZE_64K;
+
+			/*
+			 * We write all 4K page entries, even when using 64K
+			 * pages. In order to verify that the HW isn't cheating
+			 * by using the 4K PTE instead of the 64K PTE, we want
+			 * to remove all the surplus entries. If the HW skipped
+			 * the 64K PTE, it will read/write into the scratch page
+			 * instead - which we detect as missing results during
+			 * selftests.
+			 */
+			if (I915_SELFTEST_ONLY(vma->vm->scrub_64K)) {
+				u16 i;
+
+				encode = vma->vm->scratch[0].encode;
+				vaddr = kmap_atomic_px(i915_pt_entry(pd, maybe_64K));
+
+				for (i = 1; i < index; i += 16)
+					memset64(vaddr + i, encode, 15);
+
+				kunmap_atomic(vaddr);
+			}
+		}
+
+		vma->page_sizes.gtt |= page_size;
+	} while (iter->sg);
+}
+
+static void gen8_ppgtt_insert(struct i915_address_space *vm,
+			      struct i915_vma *vma,
+			      enum i915_cache_level cache_level,
+			      u32 flags)
+{
+	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(vm);
+	struct sgt_dma iter = sgt_dma(vma);
+
+	if (vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
+		gen8_ppgtt_insert_huge(vma, &iter, cache_level, flags);
+	} else  {
+		u64 idx = vma->node.start >> GEN8_PTE_SHIFT;
+
+		do {
+			struct i915_page_directory * const pdp =
+				gen8_pdp_for_page_index(vm, idx);
+
+			idx = gen8_ppgtt_insert_pte(ppgtt, pdp, &iter, idx,
+						    cache_level, flags);
+		} while (idx);
+
+		vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
+	}
+}
+
+static int gen8_init_scratch(struct i915_address_space *vm)
+{
+	int ret;
+	int i;
+
+	/*
+	 * If everybody agrees to not to write into the scratch page,
+	 * we can reuse it for all vm, keeping contexts and processes separate.
+	 */
+	if (vm->has_read_only && vm->gt->vm && !i915_is_ggtt(vm->gt->vm)) {
+		struct i915_address_space *clone = vm->gt->vm;
+
+		GEM_BUG_ON(!clone->has_read_only);
+
+		vm->scratch_order = clone->scratch_order;
+		memcpy(vm->scratch, clone->scratch, sizeof(vm->scratch));
+		px_dma(&vm->scratch[0]) = 0; /* no xfer of ownership */
+		return 0;
+	}
+
+	ret = setup_scratch_page(vm, __GFP_HIGHMEM);
+	if (ret)
+		return ret;
+
+	vm->scratch[0].encode =
+		gen8_pte_encode(px_dma(&vm->scratch[0]),
+				I915_CACHE_LLC, vm->has_read_only);
+
+	for (i = 1; i <= vm->top; i++) {
+		if (unlikely(setup_page_dma(vm, px_base(&vm->scratch[i]))))
+			goto free_scratch;
+
+		fill_px(&vm->scratch[i], vm->scratch[i - 1].encode);
+		vm->scratch[i].encode =
+			gen8_pde_encode(px_dma(&vm->scratch[i]),
+					I915_CACHE_LLC);
+	}
+
+	return 0;
+
+free_scratch:
+	free_scratch(vm);
+	return -ENOMEM;
+}
+
+static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
+{
+	struct i915_address_space *vm = &ppgtt->vm;
+	struct i915_page_directory *pd = ppgtt->pd;
+	unsigned int idx;
+
+	GEM_BUG_ON(vm->top != 2);
+	GEM_BUG_ON(gen8_pd_top_count(vm) != GEN8_3LVL_PDPES);
+
+	for (idx = 0; idx < GEN8_3LVL_PDPES; idx++) {
+		struct i915_page_directory *pde;
+
+		pde = alloc_pd(vm);
+		if (IS_ERR(pde))
+			return PTR_ERR(pde);
+
+		fill_px(pde, vm->scratch[1].encode);
+		set_pd_entry(pd, idx, pde);
+		atomic_inc(px_used(pde)); /* keep pinned */
+	}
+	wmb();
+
+	return 0;
+}
+
+static struct i915_page_directory *
+gen8_alloc_top_pd(struct i915_address_space *vm)
+{
+	const unsigned int count = gen8_pd_top_count(vm);
+	struct i915_page_directory *pd;
+
+	GEM_BUG_ON(count > ARRAY_SIZE(pd->entry));
+
+	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);
+	atomic_inc(px_used(pd)); /* mark as pinned */
+	return pd;
+}
+
+/*
+ * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
+ * with a net effect resembling a 2-level page table in normal x86 terms. Each
+ * PDP represents 1GB of memory 4 * 512 * 512 * 4096 = 4GB legacy 32b address
+ * space.
+ *
+ */
+struct i915_ppgtt *gen8_ppgtt_create(struct intel_gt *gt)
+{
+	struct i915_ppgtt *ppgtt;
+	int err;
+
+	ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
+	if (!ppgtt)
+		return ERR_PTR(-ENOMEM);
+
+	ppgtt_init(ppgtt, gt);
+	ppgtt->vm.top = i915_vm_is_4lvl(&ppgtt->vm) ? 3 : 2;
+
+	/*
+	 * From bdw, there is hw support for read-only pages in the PPGTT.
+	 *
+	 * Gen11 has HSDES#:1807136187 unresolved. Disable ro support
+	 * for now.
+	 *
+	 * Gen12 has inherited the same read-only fault issue from gen11.
+	 */
+	ppgtt->vm.has_read_only = !IS_GEN_RANGE(gt->i915, 11, 12);
+
+	/*
+	 * There are only few exceptions for gen >=6. chv and bxt.
+	 * And we are not sure about the latter so play safe for now.
+	 */
+	if (IS_CHERRYVIEW(gt->i915) || IS_BROXTON(gt->i915))
+		ppgtt->vm.pt_kmap_wc = true;
+
+	err = gen8_init_scratch(&ppgtt->vm);
+	if (err)
+		goto err_free;
+
+	ppgtt->pd = gen8_alloc_top_pd(&ppgtt->vm);
+	if (IS_ERR(ppgtt->pd)) {
+		err = PTR_ERR(ppgtt->pd);
+		goto err_free_scratch;
+	}
+
+	if (!i915_vm_is_4lvl(&ppgtt->vm)) {
+		err = gen8_preallocate_top_level_pdp(ppgtt);
+		if (err)
+			goto err_free_pd;
+	}
+
+	ppgtt->vm.bind_async_flags = I915_VMA_LOCAL_BIND;
+	ppgtt->vm.insert_entries = gen8_ppgtt_insert;
+	ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc;
+	ppgtt->vm.clear_range = gen8_ppgtt_clear;
+
+	if (intel_vgpu_active(gt->i915))
+		gen8_ppgtt_notify_vgt(ppgtt, true);
+
+	ppgtt->vm.cleanup = gen8_ppgtt_cleanup;
+
+	return ppgtt;
+
+err_free_pd:
+	__gen8_ppgtt_cleanup(&ppgtt->vm, ppgtt->pd,
+			     gen8_pd_top_count(&ppgtt->vm), ppgtt->vm.top);
+err_free_scratch:
+	free_scratch(&ppgtt->vm);
+err_free:
+	kfree(ppgtt);
+	return ERR_PTR(err);
+}