/*
 * Copyright © 2010 Daniel Vetter
 * Copyright © 2011-2014 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

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

#include <linux/fault-inject.h>
#include <linux/log2.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/stop_machine.h>

#include <asm/set_memory.h>

#include <drm/i915_drm.h>

#include "display/intel_frontbuffer.h"

#include "i915_drv.h"
#include "i915_scatterlist.h"
#include "i915_trace.h"
#include "i915_vgpu.h"
#include "intel_drv.h"

#define I915_GFP_ALLOW_FAIL (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN)

/**
 * DOC: Global GTT views
 *
 * Background and previous state
 *
 * Historically objects could exists (be bound) in global GTT space only as
 * singular instances with a view representing all of the object's backing pages
 * in a linear fashion. This view will be called a normal view.
 *
 * To support multiple views of the same object, where the number of mapped
 * pages is not equal to the backing store, or where the layout of the pages
 * is not linear, concept of a GGTT view was added.
 *
 * One example of an alternative view is a stereo display driven by a single
 * image. In this case we would have a framebuffer looking like this
 * (2x2 pages):
 *
 *    12
 *    34
 *
 * Above would represent a normal GGTT view as normally mapped for GPU or CPU
 * rendering. In contrast, fed to the display engine would be an alternative
 * view which could look something like this:
 *
 *   1212
 *   3434
 *
 * In this example both the size and layout of pages in the alternative view is
 * different from the normal view.
 *
 * Implementation and usage
 *
 * GGTT views are implemented using VMAs and are distinguished via enum
 * i915_ggtt_view_type and struct i915_ggtt_view.
 *
 * A new flavour of core GEM functions which work with GGTT bound objects were
 * added with the _ggtt_ infix, and sometimes with _view postfix to avoid
 * renaming  in large amounts of code. They take the struct i915_ggtt_view
 * parameter encapsulating all metadata required to implement a view.
 *
 * As a helper for callers which are only interested in the normal view,
 * globally const i915_ggtt_view_normal singleton instance exists. All old core
 * GEM API functions, the ones not taking the view parameter, are operating on,
 * or with the normal GGTT view.
 *
 * Code wanting to add or use a new GGTT view needs to:
 *
 * 1. Add a new enum with a suitable name.
 * 2. Extend the metadata in the i915_ggtt_view structure if required.
 * 3. Add support to i915_get_vma_pages().
 *
 * New views are required to build a scatter-gather table from within the
 * i915_get_vma_pages function. This table is stored in the vma.ggtt_view and
 * exists for the lifetime of an VMA.
 *
 * Core API is designed to have copy semantics which means that passed in
 * struct i915_ggtt_view does not need to be persistent (left around after
 * calling the core API functions).
 *
 */

static int
i915_get_ggtt_vma_pages(struct i915_vma *vma);

static void gen6_ggtt_invalidate(struct drm_i915_private *i915)
{
        struct intel_uncore *uncore = &i915->uncore;

        /*
         * Note that as an uncached mmio write, this will flush the
         * WCB of the writes into the GGTT before it triggers the invalidate.
         */
        intel_uncore_write_fw(uncore, GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
}

static void guc_ggtt_invalidate(struct drm_i915_private *i915)
{
        struct intel_uncore *uncore = &i915->uncore;

        gen6_ggtt_invalidate(i915);
        intel_uncore_write_fw(uncore, GEN8_GTCR, GEN8_GTCR_INVALIDATE);
}

static void gmch_ggtt_invalidate(struct drm_i915_private *i915)
{
        intel_gtt_chipset_flush();
}

static inline void i915_ggtt_invalidate(struct drm_i915_private *i915)
{
        i915->ggtt.invalidate(i915);
}

static int ppgtt_bind_vma(struct i915_vma *vma,
                          enum i915_cache_level cache_level,
                          u32 unused)
{
        u32 pte_flags;
        int err;

        if (!(vma->flags & I915_VMA_LOCAL_BIND)) {
                err = vma->vm->allocate_va_range(vma->vm,
                                                 vma->node.start, vma->size);
                if (err)
                        return err;
        }

        /* Applicable to VLV, and gen8+ */
        pte_flags = 0;
        if (i915_gem_object_is_readonly(vma->obj))
                pte_flags |= PTE_READ_ONLY;

        vma->vm->insert_entries(vma->vm, vma, cache_level, pte_flags);

        return 0;
}

static void ppgtt_unbind_vma(struct i915_vma *vma)
{
        vma->vm->clear_range(vma->vm, vma->node.start, vma->size);
}

static int ppgtt_set_pages(struct i915_vma *vma)
{
        GEM_BUG_ON(vma->pages);

        vma->pages = vma->obj->mm.pages;

        vma->page_sizes = vma->obj->mm.page_sizes;

        return 0;
}

static 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 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 gen8_pde_t gen8_pde_encode(const dma_addr_t addr,
                                  const enum i915_cache_level level)
{
        gen8_pde_t pde = _PAGE_PRESENT | _PAGE_RW;
        pde |= addr;
        if (level != I915_CACHE_NONE)
                pde |= PPAT_CACHED_PDE;
        else
                pde |= PPAT_UNCACHED;
        return pde;
}

#define gen8_pdpe_encode gen8_pde_encode
#define gen8_pml4e_encode gen8_pde_encode

static u64 snb_pte_encode(dma_addr_t addr,
                          enum i915_cache_level level,
                          u32 flags)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= GEN6_PTE_ADDR_ENCODE(addr);

        switch (level) {
        case I915_CACHE_L3_LLC:
        case I915_CACHE_LLC:
                pte |= GEN6_PTE_CACHE_LLC;
                break;
        case I915_CACHE_NONE:
                pte |= GEN6_PTE_UNCACHED;
                break;
        default:
                MISSING_CASE(level);
        }

        return pte;
}

static u64 ivb_pte_encode(dma_addr_t addr,
                          enum i915_cache_level level,
                          u32 flags)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= GEN6_PTE_ADDR_ENCODE(addr);

        switch (level) {
        case I915_CACHE_L3_LLC:
                pte |= GEN7_PTE_CACHE_L3_LLC;
                break;
        case I915_CACHE_LLC:
                pte |= GEN6_PTE_CACHE_LLC;
                break;
        case I915_CACHE_NONE:
                pte |= GEN6_PTE_UNCACHED;
                break;
        default:
                MISSING_CASE(level);
        }

        return pte;
}

static u64 byt_pte_encode(dma_addr_t addr,
                          enum i915_cache_level level,
                          u32 flags)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= GEN6_PTE_ADDR_ENCODE(addr);

        if (!(flags & PTE_READ_ONLY))
                pte |= BYT_PTE_WRITEABLE;

        if (level != I915_CACHE_NONE)
                pte |= BYT_PTE_SNOOPED_BY_CPU_CACHES;

        return pte;
}

static u64 hsw_pte_encode(dma_addr_t addr,
                          enum i915_cache_level level,
                          u32 flags)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= HSW_PTE_ADDR_ENCODE(addr);

        if (level != I915_CACHE_NONE)
                pte |= HSW_WB_LLC_AGE3;

        return pte;
}

static u64 iris_pte_encode(dma_addr_t addr,
                           enum i915_cache_level level,
                           u32 flags)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= HSW_PTE_ADDR_ENCODE(addr);

        switch (level) {
        case I915_CACHE_NONE:
                break;
        case I915_CACHE_WT:
                pte |= HSW_WT_ELLC_LLC_AGE3;
                break;
        default:
                pte |= HSW_WB_ELLC_LLC_AGE3;
                break;
        }

        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)
{
        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);
}

static void i915_address_space_init(struct i915_address_space *vm, int subclass)
{
        kref_init(&vm->ref);

        /*
         * 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->unbound_list);
        INIT_LIST_HEAD(&vm->bound_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);

        mutex_destroy(&vm->mutex);
}

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;
}

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

static 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);
}

#define kmap_atomic_px(px) kmap_atomic(px_base(px)->page)

#define setup_px(vm, px) setup_page_dma((vm), px_base(px))
#define cleanup_px(vm, px) cleanup_page_dma((vm), px_base(px))
#define fill_px(vm, px, v) fill_page_dma((vm), px_base(px), (v))
#define fill32_px(vm, px, v) fill_page_dma_32((vm), px_base(px), (v))

static void fill_page_dma(struct i915_address_space *vm,
                          struct i915_page_dma *p,
                          const u64 val)
{
        u64 * const vaddr = kmap_atomic(p->page);

        memset64(vaddr, val, PAGE_SIZE / sizeof(val));

        kunmap_atomic(vaddr);
}

static void fill_page_dma_32(struct i915_address_space *vm,
                             struct i915_page_dma *p,
                             const u32 v)
{
        fill_page_dma(vm, p, (u64)v << 32 | v);
}

static 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 {
                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_page.page = page;
                vm->scratch_page.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);
}

static void cleanup_scratch_page(struct i915_address_space *vm)
{
        struct i915_page_dma *p = &vm->scratch_page;
        int order = vm->scratch_order;

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

static struct i915_page_table *alloc_pt(struct i915_address_space *vm)
{
        struct i915_page_table *pt;

        pt = kmalloc(sizeof(*pt), I915_GFP_ALLOW_FAIL);
        if (unlikely(!pt))
                return ERR_PTR(-ENOMEM);

        if (unlikely(setup_px(vm, pt))) {
                kfree(pt);
                return ERR_PTR(-ENOMEM);
        }

        atomic_set(&pt->used, 0);

        return pt;
}

static void free_pt(struct i915_address_space *vm, struct i915_page_table *pt)
{
        cleanup_px(vm, pt);
        kfree(pt);
}

static void gen8_initialize_pt(struct i915_address_space *vm,
                               struct i915_page_table *pt)
{
        fill_px(vm, pt, vm->scratch_pte);
}

static void gen6_initialize_pt(struct i915_address_space *vm,
                               struct i915_page_table *pt)
{
        fill32_px(vm, pt, vm->scratch_pte);
}

static struct i915_page_directory *__alloc_pd(void)
{
        struct i915_page_directory *pd;

        pd = kmalloc(sizeof(*pd), I915_GFP_ALLOW_FAIL);

        if (unlikely(!pd))
                return NULL;

        memset(&pd->base, 0, sizeof(pd->base));
        atomic_set(&pd->used, 0);
        spin_lock_init(&pd->lock);

        /* for safety */
        pd->entry[0] = NULL;

        return pd;
}

static struct i915_page_directory *alloc_pd(struct i915_address_space *vm)
{
        struct i915_page_directory *pd;

        pd = __alloc_pd();
        if (unlikely(!pd))
                return ERR_PTR(-ENOMEM);

        if (unlikely(setup_px(vm, pd))) {
                kfree(pd);
                return ERR_PTR(-ENOMEM);
        }

        return pd;
}

static inline bool pd_has_phys_page(const struct i915_page_directory * const pd)
{
        return pd->base.page;
}

static void free_pd(struct i915_address_space *vm,
                    struct i915_page_directory *pd)
{
        if (likely(pd_has_phys_page(pd)))
                cleanup_px(vm, pd);

        kfree(pd);
}

static void init_pd_with_page(struct i915_address_space *vm,
                              struct i915_page_directory * const pd,
                              struct i915_page_table *pt)
{
        fill_px(vm, pd, gen8_pde_encode(px_dma(pt), I915_CACHE_LLC));
        memset_p(pd->entry, pt, 512);
}

static void init_pd(struct i915_address_space *vm,
                    struct i915_page_directory * const pd,
                    struct i915_page_directory * const to)
{
        GEM_DEBUG_BUG_ON(!pd_has_phys_page(pd));

        fill_px(vm, pd, gen8_pdpe_encode(px_dma(to), I915_CACHE_LLC));
        memset_p(pd->entry, to, 512);
}

/*
 * PDE TLBs are a pain to invalidate on GEN8+. When we modify
 * the page table structures, we mark them dirty so that
 * context switching/execlist queuing code takes extra steps
 * to ensure that tlbs are flushed.
 */
static void mark_tlbs_dirty(struct i915_ppgtt *ppgtt)
{
        ppgtt->pd_dirty_engines = ALL_ENGINES;
}

/* Removes entries from a single page table, releasing it if it's empty.
 * Caller can use the return value to update higher-level entries.
 */
static bool gen8_ppgtt_clear_pt(const struct i915_address_space *vm,
                                struct i915_page_table *pt,
                                u64 start, u64 length)
{
        unsigned int num_entries = gen8_pte_count(start, length);
        gen8_pte_t *vaddr;

        vaddr = kmap_atomic_px(pt);
        memset64(vaddr + gen8_pte_index(start), vm->scratch_pte, num_entries);
        kunmap_atomic(vaddr);

        GEM_BUG_ON(num_entries > atomic_read(&pt->used));
        return !atomic_sub_return(num_entries, &pt->used);
}

static void gen8_ppgtt_set_pde(struct i915_address_space *vm,
                               struct i915_page_directory *pd,
                               struct i915_page_table *pt,
                               unsigned int pde)
{
        gen8_pde_t *vaddr;

        vaddr = kmap_atomic_px(pd);
        vaddr[pde] = gen8_pde_encode(px_dma(pt), I915_CACHE_LLC);
        kunmap_atomic(vaddr);
}

static bool gen8_ppgtt_clear_pd(struct i915_address_space *vm,
                                struct i915_page_directory *pd,
                                u64 start, u64 length)
{
        struct i915_page_table *pt;
        u32 pde;

        gen8_for_each_pde(pt, pd, start, length, pde) {
                bool free = false;

                GEM_BUG_ON(pt == vm->scratch_pt);

                if (!gen8_ppgtt_clear_pt(vm, pt, start, length))
                        continue;

                spin_lock(&pd->lock);
                if (!atomic_read(&pt->used)) {
                        gen8_ppgtt_set_pde(vm, pd, vm->scratch_pt, pde);
                        pd->entry[pde] = vm->scratch_pt;

                        GEM_BUG_ON(!atomic_read(&pd->used));
                        atomic_dec(&pd->used);
                        free = true;
                }
                spin_unlock(&pd->lock);
                if (free)
                        free_pt(vm, pt);
        }

        return !atomic_read(&pd->used);
}

static void gen8_ppgtt_set_pdpe(struct i915_page_directory *pdp,
                                struct i915_page_directory *pd,
                                unsigned int pdpe)
{
        gen8_ppgtt_pdpe_t *vaddr;

        if (!pd_has_phys_page(pdp))
                return;

        vaddr = kmap_atomic_px(pdp);
        vaddr[pdpe] = gen8_pdpe_encode(px_dma(pd), I915_CACHE_LLC);
        kunmap_atomic(vaddr);
}

/* Removes entries from a single page dir pointer, releasing it if it's empty.
 * Caller can use the return value to update higher-level entries
 */
static bool gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
                                 struct i915_page_directory * const pdp,
                                 u64 start, u64 length)
{
        struct i915_page_directory *pd;
        unsigned int pdpe;

        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                bool free = false;

                GEM_BUG_ON(pd == vm->scratch_pd);

                if (!gen8_ppgtt_clear_pd(vm, pd, start, length))
                        continue;

                spin_lock(&pdp->lock);
                if (!atomic_read(&pd->used)) {
                        gen8_ppgtt_set_pdpe(pdp, vm->scratch_pd, pdpe);
                        pdp->entry[pdpe] = vm->scratch_pd;

                        GEM_BUG_ON(!atomic_read(&pdp->used));
                        atomic_dec(&pdp->used);
                        free = true;
                }
                spin_unlock(&pdp->lock);
                if (free)
                        free_pd(vm, pd);
        }

        return !atomic_read(&pdp->used);
}

static void gen8_ppgtt_clear_3lvl(struct i915_address_space *vm,
                                  u64 start, u64 length)
{
        gen8_ppgtt_clear_pdp(vm, i915_vm_to_ppgtt(vm)->pd, start, length);
}

static void gen8_ppgtt_set_pml4e(struct i915_page_directory *pml4,
                                 struct i915_page_directory *pdp,
                                 unsigned int pml4e)
{
        gen8_ppgtt_pml4e_t *vaddr;

        vaddr = kmap_atomic_px(pml4);
        vaddr[pml4e] = gen8_pml4e_encode(px_dma(pdp), I915_CACHE_LLC);
        kunmap_atomic(vaddr);
}

/* Removes entries from a single pml4.
 * This is the top-level structure in 4-level page tables used on gen8+.
 * Empty entries are always scratch pml4e.
 */
static void gen8_ppgtt_clear_4lvl(struct i915_address_space *vm,
                                  u64 start, u64 length)
{
        struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory * const pml4 = ppgtt->pd;
        struct i915_page_directory *pdp;
        unsigned int pml4e;

        GEM_BUG_ON(!i915_vm_is_4lvl(vm));

        gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
                bool free = false;
                GEM_BUG_ON(pdp == vm->scratch_pdp);

                if (!gen8_ppgtt_clear_pdp(vm, pdp, start, length))
                        continue;

                spin_lock(&pml4->lock);
                if (!atomic_read(&pdp->used)) {
                        gen8_ppgtt_set_pml4e(pml4, vm->scratch_pdp, pml4e);
                        pml4->entry[pml4e] = vm->scratch_pdp;
                        free = true;
                }
                spin_unlock(&pml4->lock);
                if (free)
                        free_pd(vm, pdp);
        }
}

static inline struct sgt_dma {
        struct scatterlist *sg;
        dma_addr_t dma, max;
} sgt_dma(struct i915_vma *vma) {
        struct scatterlist *sg = vma->pages->sgl;
        dma_addr_t addr = sg_dma_address(sg);
        return (struct sgt_dma) { sg, addr, addr + sg->length };
}

struct gen8_insert_pte {
        u16 pml4e;
        u16 pdpe;
        u16 pde;
        u16 pte;
};

static __always_inline struct gen8_insert_pte gen8_insert_pte(u64 start)
{
        return (struct gen8_insert_pte) {
                 gen8_pml4e_index(start),
                 gen8_pdpe_index(start),
                 gen8_pde_index(start),
                 gen8_pte_index(start),
        };
}

static __always_inline bool
gen8_ppgtt_insert_pte_entries(struct i915_ppgtt *ppgtt,
                              struct i915_page_directory *pdp,
                              struct sgt_dma *iter,
                              struct gen8_insert_pte *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;
        bool ret;

        GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(&ppgtt->vm));
        pd = i915_pd_entry(pdp, idx->pdpe);
        vaddr = kmap_atomic_px(i915_pt_entry(pd, idx->pde));
        do {
                vaddr[idx->pte] = pte_encode | iter->dma;

                iter->dma += I915_GTT_PAGE_SIZE;
                if (iter->dma >= iter->max) {
                        iter->sg = __sg_next(iter->sg);
                        if (!iter->sg) {
                                ret = false;
                                break;
                        }

                        iter->dma = sg_dma_address(iter->sg);
                        iter->max = iter->dma + iter->sg->length;
                }

                if (++idx->pte == GEN8_PTES) {
                        idx->pte = 0;

                        if (++idx->pde == I915_PDES) {
                                idx->pde = 0;

                                /* Limited by sg length for 3lvl */
                                if (++idx->pdpe == GEN8_PML4ES_PER_PML4) {
                                        idx->pdpe = 0;
                                        ret = true;
                                        break;
                                }

                                GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(&ppgtt->vm));
                                pd = pdp->entry[idx->pdpe];
                        }

                        kunmap_atomic(vaddr);
                        vaddr = kmap_atomic_px(i915_pt_entry(pd, idx->pde));
                }
        } while (1);
        kunmap_atomic(vaddr);

        return ret;
}

static void gen8_ppgtt_insert_3lvl(struct i915_address_space *vm,
                                   struct i915_vma *vma,
                                   enum i915_cache_level cache_level,
                                   u32 flags)
{
        struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct sgt_dma iter = sgt_dma(vma);
        struct gen8_insert_pte idx = gen8_insert_pte(vma->node.start);

        gen8_ppgtt_insert_pte_entries(ppgtt, ppgtt->pd, &iter, &idx,
                                      cache_level, flags);

        vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
}

static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
                                           struct i915_page_directory *pml4,
                                           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;

        do {
                struct gen8_insert_pte idx = gen8_insert_pte(start);
                struct i915_page_directory *pdp =
                        i915_pdp_entry(pml4, idx.pml4e);
                struct i915_page_directory *pd = i915_pd_entry(pdp, idx.pdpe);
                unsigned int page_size;
                bool maybe_64K = false;
                gen8_pte_t encode = pte_encode;
                gen8_pte_t *vaddr;
                u16 index, max;

                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 && !idx.pte) {
                        index = idx.pde;
                        max = I915_PDES;
                        page_size = I915_GTT_PAGE_SIZE_2M;

                        encode |= GEN8_PDE_PS_2M;

                        vaddr = kmap_atomic_px(pd);
                } else {
                        struct i915_page_table *pt = i915_pt_entry(pd, idx.pde);

                        index = idx.pte;
                        max = GEN8_PTES;
                        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 >= (max - index) * I915_GTT_PAGE_SIZE))
                                maybe_64K = true;

                        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 && index < max &&
                                    !(IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
                                      (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
                                       rem >= (max - index) * I915_GTT_PAGE_SIZE)))
                                        maybe_64K = false;

                                if (unlikely(!IS_ALIGNED(iter->dma, page_size)))
                                        break;
                        }
                } while (rem >= page_size && index < max);

                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 &&
                    (index == max ||
                     (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[idx.pde] |= 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_pte;
                                vaddr = kmap_atomic_px(i915_pt_entry(pd,
                                                                     idx.pde));

                                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_4lvl(struct i915_address_space *vm,
                                   struct i915_vma *vma,
                                   enum i915_cache_level cache_level,
                                   u32 flags)
{
        struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct sgt_dma iter = sgt_dma(vma);
        struct i915_page_directory * const pml4 = ppgtt->pd;

        if (vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
                gen8_ppgtt_insert_huge_entries(vma, pml4, &iter, cache_level,
                                               flags);
        } else {
                struct gen8_insert_pte idx = gen8_insert_pte(vma->node.start);

                while (gen8_ppgtt_insert_pte_entries(ppgtt,
                                                     i915_pdp_entry(pml4, idx.pml4e++),
                                                     &iter, &idx, cache_level,
                                                     flags))
                        GEM_BUG_ON(idx.pml4e >= GEN8_PML4ES_PER_PML4);

                vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
        }
}

static void gen8_free_page_tables(struct i915_address_space *vm,
                                  struct i915_page_directory *pd)
{
        int i;

        for (i = 0; i < I915_PDES; i++) {
                if (pd->entry[i] != vm->scratch_pt)
                        free_pt(vm, pd->entry[i]);
        }
}

static int gen8_init_scratch(struct i915_address_space *vm)
{
        int ret;

        /*
         * 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->i915->kernel_context &&
            vm->i915->kernel_context->vm) {
                struct i915_address_space *clone = vm->i915->kernel_context->vm;

                GEM_BUG_ON(!clone->has_read_only);

                vm->scratch_order = clone->scratch_order;
                vm->scratch_pte = clone->scratch_pte;
                vm->scratch_pt  = clone->scratch_pt;
                vm->scratch_pd  = clone->scratch_pd;
                vm->scratch_pdp = clone->scratch_pdp;
                return 0;
        }

        ret = setup_scratch_page(vm, __GFP_HIGHMEM);
        if (ret)
                return ret;

        vm->scratch_pte =
                gen8_pte_encode(vm->scratch_page.daddr,
                                I915_CACHE_LLC,
                                vm->has_read_only);

        vm->scratch_pt = alloc_pt(vm);
        if (IS_ERR(vm->scratch_pt)) {
                ret = PTR_ERR(vm->scratch_pt);
                goto free_scratch_page;
        }

        vm->scratch_pd = alloc_pd(vm);
        if (IS_ERR(vm->scratch_pd)) {
                ret = PTR_ERR(vm->scratch_pd);
                goto free_pt;
        }

        if (i915_vm_is_4lvl(vm)) {
                vm->scratch_pdp = alloc_pd(vm);
                if (IS_ERR(vm->scratch_pdp)) {
                        ret = PTR_ERR(vm->scratch_pdp);
                        goto free_pd;
                }
        }

        gen8_initialize_pt(vm, vm->scratch_pt);
        init_pd_with_page(vm, vm->scratch_pd, vm->scratch_pt);
        if (i915_vm_is_4lvl(vm))
                init_pd(vm, vm->scratch_pdp, vm->scratch_pd);

        return 0;

free_pd:
        free_pd(vm, vm->scratch_pd);
free_pt:
        free_pt(vm, vm->scratch_pt);
free_scratch_page:
        cleanup_scratch_page(vm);

        return ret;
}

static int gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
{
        struct i915_address_space *vm = &ppgtt->vm;
        struct drm_i915_private *dev_priv = vm->i915;
        enum vgt_g2v_type msg;
        int i;

        if (i915_vm_is_4lvl(vm)) {
                const u64 daddr = px_dma(ppgtt->pd);

                I915_WRITE(vgtif_reg(pdp[0].lo), lower_32_bits(daddr));
                I915_WRITE(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);

                        I915_WRITE(vgtif_reg(pdp[i].lo), lower_32_bits(daddr));
                        I915_WRITE(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);
        }

        I915_WRITE(vgtif_reg(g2v_notify), msg);

        return 0;
}

static void gen8_free_scratch(struct i915_address_space *vm)
{
        if (!vm->scratch_page.daddr)
                return;

        if (i915_vm_is_4lvl(vm))
                free_pd(vm, vm->scratch_pdp);
        free_pd(vm, vm->scratch_pd);
        free_pt(vm, vm->scratch_pt);
        cleanup_scratch_page(vm);
}

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] == vm->scratch_pd)
                        continue;

                gen8_free_page_tables(vm, pdp->entry[i]);
                free_pd(vm, pdp->entry[i]);
        }

        free_pd(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 (pdp == ppgtt->vm.scratch_pdp)
                        continue;

                gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, pdp);
        }

        free_pd(&ppgtt->vm, pml4);
}

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))
                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_free_scratch(vm);
}

static int gen8_ppgtt_alloc_pd(struct i915_address_space *vm,
                               struct i915_page_directory *pd,
                               u64 start, u64 length)
{
        struct i915_page_table *pt, *alloc = NULL;
        u64 from = start;
        unsigned int pde;
        int ret = 0;

        spin_lock(&pd->lock);
        gen8_for_each_pde(pt, pd, start, length, pde) {
                const int count = gen8_pte_count(start, length);

                if (pt == vm->scratch_pt) {
                        spin_unlock(&pd->lock);

                        pt = fetch_and_zero(&alloc);
                        if (!pt)
                                pt = alloc_pt(vm);
                        if (IS_ERR(pt)) {
                                ret = PTR_ERR(pt);
                                goto unwind;
                        }

                        if (count < GEN8_PTES || intel_vgpu_active(vm->i915))
                                gen8_initialize_pt(vm, pt);

                        spin_lock(&pd->lock);
                        if (pd->entry[pde] == vm->scratch_pt) {
                                gen8_ppgtt_set_pde(vm, pd, pt, pde);
                                pd->entry[pde] = pt;
                                atomic_inc(&pd->used);
                        } else {
                                alloc = pt;
                                pt = pd->entry[pde];
                        }
                }

                atomic_add(count, &pt->used);
        }
        spin_unlock(&pd->lock);
        goto out;

unwind:
        gen8_ppgtt_clear_pd(vm, pd, from, start - from);
out:
        if (alloc)
                free_pt(vm, alloc);
        return ret;
}

static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
                                struct i915_page_directory *pdp,
                                u64 start, u64 length)
{
        struct i915_page_directory *pd, *alloc = NULL;
        u64 from = start;
        unsigned int pdpe;
        int ret = 0;

        spin_lock(&pdp->lock);
        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                if (pd == vm->scratch_pd) {
                        spin_unlock(&pdp->lock);

                        pd = fetch_and_zero(&alloc);
                        if (!pd)
                                pd = alloc_pd(vm);
                        if (IS_ERR(pd)) {
                                ret = PTR_ERR(pd);
                                goto unwind;
                        }

                        init_pd_with_page(vm, pd, vm->scratch_pt);

                        spin_lock(&pdp->lock);
                        if (pdp->entry[pdpe] == vm->scratch_pd) {
                                gen8_ppgtt_set_pdpe(pdp, pd, pdpe);
                                pdp->entry[pdpe] = pd;
                                atomic_inc(&pdp->used);
                        } else {
                                alloc = pd;
                                pd = pdp->entry[pdpe];
                        }
                }
                atomic_inc(&pd->used);
                spin_unlock(&pdp->lock);

                ret = gen8_ppgtt_alloc_pd(vm, pd, start, length);
                if (unlikely(ret))
                        goto unwind_pd;

                spin_lock(&pdp->lock);
                atomic_dec(&pd->used);
        }
        spin_unlock(&pdp->lock);
        goto out;

unwind_pd:
        spin_lock(&pdp->lock);
        if (atomic_dec_and_test(&pd->used)) {
                gen8_ppgtt_set_pdpe(pdp, vm->scratch_pd, pdpe);
                pdp->entry[pdpe] = vm->scratch_pd;
                GEM_BUG_ON(!atomic_read(&pdp->used));
                atomic_dec(&pdp->used);
                GEM_BUG_ON(alloc);
                alloc = pd; /* defer the free to after the lock */
        }
        spin_unlock(&pdp->lock);
unwind:
        gen8_ppgtt_clear_pdp(vm, pdp, from, start - from);
out:
        if (alloc)
                free_pd(vm, alloc);
        return ret;
}

static int gen8_ppgtt_alloc_3lvl(struct i915_address_space *vm,
                                 u64 start, u64 length)
{
        return gen8_ppgtt_alloc_pdp(vm,
                                    i915_vm_to_ppgtt(vm)->pd, start, length);
}

static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
                                 u64 start, u64 length)
{
        struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory * const pml4 = ppgtt->pd;
        struct i915_page_directory *pdp, *alloc = NULL;
        u64 from = start;
        int ret = 0;
        u32 pml4e;

        spin_lock(&pml4->lock);
        gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
                if (pdp == vm->scratch_pdp) {
                        spin_unlock(&pml4->lock);

                        pdp = fetch_and_zero(&alloc);
                        if (!pdp)
                                pdp = alloc_pd(vm);
                        if (IS_ERR(pdp)) {
                                ret = PTR_ERR(pdp);
                                goto unwind;
                        }

                        init_pd(vm, pdp, vm->scratch_pd);

                        spin_lock(&pml4->lock);
                        if (pml4->entry[pml4e] == vm->scratch_pdp) {
                                gen8_ppgtt_set_pml4e(pml4, pdp, pml4e);
                                pml4->entry[pml4e] = pdp;
                        } else {
                                alloc = pdp;
                                pdp = pml4->entry[pml4e];
                        }
                }
                atomic_inc(&pdp->used);
                spin_unlock(&pml4->lock);

                ret = gen8_ppgtt_alloc_pdp(vm, pdp, start, length);
                if (unlikely(ret))
                        goto unwind_pdp;

                spin_lock(&pml4->lock);
                atomic_dec(&pdp->used);
        }
        spin_unlock(&pml4->lock);
        goto out;

unwind_pdp:
        spin_lock(&pml4->lock);
        if (atomic_dec_and_test(&pdp->used)) {
                gen8_ppgtt_set_pml4e(pml4, vm->scratch_pdp, pml4e);
                pml4->entry[pml4e] = vm->scratch_pdp;
                GEM_BUG_ON(alloc);
                alloc = pdp; /* defer the free until after the lock */
        }
        spin_unlock(&pml4->lock);
unwind:
        gen8_ppgtt_clear_4lvl(vm, from, start - from);
out:
        if (alloc)
                free_pd(vm, alloc);
        return ret;
}

static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
{
        struct i915_address_space *vm = &ppgtt->vm;
        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;

                init_pd_with_page(vm, pd, vm->scratch_pt);
                gen8_ppgtt_set_pdpe(pdp, pd, pdpe);

                atomic_inc(&pdp->used);
        }

        atomic_inc(&pdp->used); /* never remove */

        return 0;

unwind:
        start -= from;
        gen8_for_each_pdpe(pd, pdp, from, start, pdpe) {
                gen8_ppgtt_set_pdpe(pdp, vm->scratch_pd, pdpe);
                free_pd(vm, pd);
        }
        atomic_set(&pdp->used, 0);
        return -ENOMEM;
}

static void ppgtt_init(struct drm_i915_private *i915,
                       struct i915_ppgtt *ppgtt)
{
        ppgtt->vm.i915 = i915;
        ppgtt->vm.dma = &i915->drm.pdev->dev;
        ppgtt->vm.total = BIT_ULL(INTEL_INFO(i915)->ppgtt_size);

        i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);

        ppgtt->vm.vma_ops.bind_vma    = ppgtt_bind_vma;
        ppgtt->vm.vma_ops.unbind_vma  = ppgtt_unbind_vma;
        ppgtt->vm.vma_ops.set_pages   = ppgtt_set_pages;
        ppgtt->vm.vma_ops.clear_pages = clear_pages;
}

/*
 * 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.
 *
 */
static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
{
        struct i915_ppgtt *ppgtt;
        int err;

        ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
        if (!ppgtt)
                return ERR_PTR(-ENOMEM);

        ppgtt_init(i915, ppgtt);

        /*
         * From bdw, there is hw support for read-only pages in the PPGTT.
         *
         * Gen11 has HSDES#:1807136187 unresolved. Disable ro support
         * for now.
         */
        ppgtt->vm.has_read_only = INTEL_GEN(i915) != 11;

        /* 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(i915) || IS_BROXTON(i915))
                ppgtt->vm.pt_kmap_wc = true;

        err = gen8_init_scratch(&ppgtt->vm);
        if (err)
                goto err_free;

        ppgtt->pd = __alloc_pd();
        if (!ppgtt->pd) {
                err = -ENOMEM;
                goto err_free_scratch;
        }

        if (i915_vm_is_4lvl(&ppgtt->vm)) {
                err = setup_px(&ppgtt->vm, ppgtt->pd);
                if (err)
                        goto err_free_pdp;

                init_pd(&ppgtt->vm, ppgtt->pd, ppgtt->vm.scratch_pdp);

                ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc_4lvl;
                ppgtt->vm.insert_entries = gen8_ppgtt_insert_4lvl;
                ppgtt->vm.clear_range = gen8_ppgtt_clear_4lvl;
        } else {
                /*
                 * We don't need to setup dma for top level pdp, only
                 * for entries. So point entries to scratch.
                 */
                memset_p(ppgtt->pd->entry, ppgtt->vm.scratch_pd,
                         GEN8_3LVL_PDPES);

                if (intel_vgpu_active(i915)) {
                        err = gen8_preallocate_top_level_pdp(ppgtt);
                        if (err)
                                goto err_free_pdp;
                }

                ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc_3lvl;
                ppgtt->vm.insert_entries = gen8_ppgtt_insert_3lvl;
                ppgtt->vm.clear_range = gen8_ppgtt_clear_3lvl;
        }

        if (intel_vgpu_active(i915))
                gen8_ppgtt_notify_vgt(ppgtt, true);

        ppgtt->vm.cleanup = gen8_ppgtt_cleanup;

        return ppgtt;

err_free_pdp:
        free_pd(&ppgtt->vm, ppgtt->pd);
err_free_scratch:
        gen8_free_scratch(&ppgtt->vm);
err_free:
        kfree(ppgtt);
        return ERR_PTR(err);
}

/* Write pde (index) from the page directory @pd to the page table @pt */
static inline void gen6_write_pde(const struct gen6_ppgtt *ppgtt,
                                  const unsigned int pde,
                                  const struct i915_page_table *pt)
{
        /* Caller needs to make sure the write completes if necessary */
        iowrite32(GEN6_PDE_ADDR_ENCODE(px_dma(pt)) | GEN6_PDE_VALID,
                  ppgtt->pd_addr + pde);
}

static void gen7_ppgtt_enable(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;
        u32 ecochk, ecobits;
        enum intel_engine_id id;

        ecobits = I915_READ(GAC_ECO_BITS);
        I915_WRITE(GAC_ECO_BITS, ecobits | ECOBITS_PPGTT_CACHE64B);

        ecochk = I915_READ(GAM_ECOCHK);
        if (IS_HASWELL(dev_priv)) {
                ecochk |= ECOCHK_PPGTT_WB_HSW;
        } else {
                ecochk |= ECOCHK_PPGTT_LLC_IVB;
                ecochk &= ~ECOCHK_PPGTT_GFDT_IVB;
        }
        I915_WRITE(GAM_ECOCHK, ecochk);

        for_each_engine(engine, dev_priv, id) {
                /* GFX_MODE is per-ring on gen7+ */
                ENGINE_WRITE(engine,
                             RING_MODE_GEN7,
                             _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE));
        }
}

static void gen6_ppgtt_enable(struct drm_i915_private *dev_priv)
{
        u32 ecochk, gab_ctl, ecobits;

        ecobits = I915_READ(GAC_ECO_BITS);
        I915_WRITE(GAC_ECO_BITS, ecobits | ECOBITS_SNB_BIT |
                   ECOBITS_PPGTT_CACHE64B);

        gab_ctl = I915_READ(GAB_CTL);
        I915_WRITE(GAB_CTL, gab_ctl | GAB_CTL_CONT_AFTER_PAGEFAULT);

        ecochk = I915_READ(GAM_ECOCHK);
        I915_WRITE(GAM_ECOCHK, ecochk | ECOCHK_SNB_BIT | ECOCHK_PPGTT_CACHE64B);

        if (HAS_PPGTT(dev_priv)) /* may be disabled for VT-d */
                I915_WRITE(GFX_MODE, _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE));
}

/* PPGTT support for Sandybdrige/Gen6 and later */
static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
                                   u64 start, u64 length)
{
        struct gen6_ppgtt * const ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
        const unsigned int first_entry = start / I915_GTT_PAGE_SIZE;
        const gen6_pte_t scratch_pte = vm->scratch_pte;
        unsigned int pde = first_entry / GEN6_PTES;
        unsigned int pte = first_entry % GEN6_PTES;
        unsigned int num_entries = length / I915_GTT_PAGE_SIZE;

        while (num_entries) {
                struct i915_page_table * const pt =
                        i915_pt_entry(ppgtt->base.pd, pde++);
                const unsigned int count = min(num_entries, GEN6_PTES - pte);
                gen6_pte_t *vaddr;

                GEM_BUG_ON(pt == vm->scratch_pt);

                num_entries -= count;

                GEM_BUG_ON(count > atomic_read(&pt->used));
                if (!atomic_sub_return(count, &pt->used))
                        ppgtt->scan_for_unused_pt = true;

                /*
                 * Note that the hw doesn't support removing PDE on the fly
                 * (they are cached inside the context with no means to
                 * invalidate the cache), so we can only reset the PTE
                 * entries back to scratch.
                 */

                vaddr = kmap_atomic_px(pt);
                memset32(vaddr + pte, scratch_pte, count);
                kunmap_atomic(vaddr);

                pte = 0;
        }
}

static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
                                      struct i915_vma *vma,
                                      enum i915_cache_level cache_level,
                                      u32 flags)
{
        struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory * const pd = ppgtt->pd;
        unsigned first_entry = vma->node.start / I915_GTT_PAGE_SIZE;
        unsigned act_pt = first_entry / GEN6_PTES;
        unsigned act_pte = first_entry % GEN6_PTES;
        const u32 pte_encode = vm->pte_encode(0, cache_level, flags);
        struct sgt_dma iter = sgt_dma(vma);
        gen6_pte_t *vaddr;

        GEM_BUG_ON(i915_pt_entry(pd, act_pt) == vm->scratch_pt);

        vaddr = kmap_atomic_px(i915_pt_entry(pd, act_pt));
        do {
                vaddr[act_pte] = pte_encode | GEN6_PTE_ADDR_ENCODE(iter.dma);

                iter.dma += I915_GTT_PAGE_SIZE;
                if (iter.dma == iter.max) {
                        iter.sg = __sg_next(iter.sg);
                        if (!iter.sg)
                                break;

                        iter.dma = sg_dma_address(iter.sg);
                        iter.max = iter.dma + iter.sg->length;
                }

                if (++act_pte == GEN6_PTES) {
                        kunmap_atomic(vaddr);
                        vaddr = kmap_atomic_px(i915_pt_entry(pd, ++act_pt));
                        act_pte = 0;
                }
        } while (1);
        kunmap_atomic(vaddr);

        vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
}

static int gen6_alloc_va_range(struct i915_address_space *vm,
                               u64 start, u64 length)
{
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
        struct i915_page_directory * const pd = ppgtt->base.pd;
        struct i915_page_table *pt, *alloc = NULL;
        intel_wakeref_t wakeref;
        u64 from = start;
        unsigned int pde;
        bool flush = false;
        int ret = 0;

        wakeref = intel_runtime_pm_get(&vm->i915->runtime_pm);

        spin_lock(&pd->lock);
        gen6_for_each_pde(pt, pd, start, length, pde) {
                const unsigned int count = gen6_pte_count(start, length);

                if (pt == vm->scratch_pt) {
                        spin_unlock(&pd->lock);

                        pt = fetch_and_zero(&alloc);
                        if (!pt)
                                pt = alloc_pt(vm);
                        if (IS_ERR(pt)) {
                                ret = PTR_ERR(pt);
                                goto unwind_out;
                        }

                        gen6_initialize_pt(vm, pt);

                        spin_lock(&pd->lock);
                        if (pd->entry[pde] == vm->scratch_pt) {
                                pd->entry[pde] = pt;
                                if (i915_vma_is_bound(ppgtt->vma,
                                                      I915_VMA_GLOBAL_BIND)) {
                                        gen6_write_pde(ppgtt, pde, pt);
                                        flush = true;
                                }
                        } else {
                                alloc = pt;
                                pt = pd->entry[pde];
                        }
                }

                atomic_add(count, &pt->used);
        }
        spin_unlock(&pd->lock);

        if (flush) {
                mark_tlbs_dirty(&ppgtt->base);
                gen6_ggtt_invalidate(vm->i915);
        }

        goto out;

unwind_out:
        gen6_ppgtt_clear_range(vm, from, start - from);
out:
        if (alloc)
                free_pt(vm, alloc);
        intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);
        return ret;
}

static int gen6_ppgtt_init_scratch(struct gen6_ppgtt *ppgtt)
{
        struct i915_address_space * const vm = &ppgtt->base.vm;
        struct i915_page_directory * const pd = ppgtt->base.pd;
        struct i915_page_table *unused;
        u32 pde;
        int ret;

        ret = setup_scratch_page(vm, __GFP_HIGHMEM);
        if (ret)
                return ret;

        vm->scratch_pte = vm->pte_encode(vm->scratch_page.daddr,
                                         I915_CACHE_NONE,
                                         PTE_READ_ONLY);

        vm->scratch_pt = alloc_pt(vm);
        if (IS_ERR(vm->scratch_pt)) {
                cleanup_scratch_page(vm);
                return PTR_ERR(vm->scratch_pt);
        }

        gen6_initialize_pt(vm, vm->scratch_pt);

        gen6_for_all_pdes(unused, pd, pde)
                pd->entry[pde] = vm->scratch_pt;

        return 0;
}

static void gen6_ppgtt_free_scratch(struct i915_address_space *vm)
{
        free_pt(vm, vm->scratch_pt);
        cleanup_scratch_page(vm);
}

static void gen6_ppgtt_free_pd(struct gen6_ppgtt *ppgtt)
{
        struct i915_page_directory * const pd = ppgtt->base.pd;
        struct i915_page_table *pt;
        u32 pde;

        gen6_for_all_pdes(pt, pd, pde)
                if (pt != ppgtt->base.vm.scratch_pt)
                        free_pt(&ppgtt->base.vm, pt);
}

struct gen6_ppgtt_cleanup_work {
        struct work_struct base;
        struct i915_vma *vma;
};

static void gen6_ppgtt_cleanup_work(struct work_struct *wrk)
{
        struct gen6_ppgtt_cleanup_work *work =
                container_of(wrk, typeof(*work), base);
        /* Side note, vma->vm is the GGTT not the ppgtt we just destroyed! */
        struct drm_i915_private *i915 = work->vma->vm->i915;

        mutex_lock(&i915->drm.struct_mutex);
        i915_vma_destroy(work->vma);
        mutex_unlock(&i915->drm.struct_mutex);

        kfree(work);
}

static int nop_set_pages(struct i915_vma *vma)
{
        return -ENODEV;
}

static void nop_clear_pages(struct i915_vma *vma)
{
}

static int nop_bind(struct i915_vma *vma,
                    enum i915_cache_level cache_level,
                    u32 unused)
{
        return -ENODEV;
}

static void nop_unbind(struct i915_vma *vma)
{
}

static const struct i915_vma_ops nop_vma_ops = {
        .set_pages = nop_set_pages,
        .clear_pages = nop_clear_pages,
        .bind_vma = nop_bind,
        .unbind_vma = nop_unbind,
};

static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
{
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
        struct gen6_ppgtt_cleanup_work *work = ppgtt->work;

        /* FIXME remove the struct_mutex to bring the locking under control */
        INIT_WORK(&work->base, gen6_ppgtt_cleanup_work);
        work->vma = ppgtt->vma;
        work->vma->ops = &nop_vma_ops;
        schedule_work(&work->base);

        gen6_ppgtt_free_pd(ppgtt);
        gen6_ppgtt_free_scratch(vm);
        kfree(ppgtt->base.pd);
}

static int pd_vma_set_pages(struct i915_vma *vma)
{
        vma->pages = ERR_PTR(-ENODEV);
        return 0;
}

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

        vma->pages = NULL;
}

static int pd_vma_bind(struct i915_vma *vma,
                       enum i915_cache_level cache_level,
                       u32 unused)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vma->vm);
        struct gen6_ppgtt *ppgtt = vma->private;
        u32 ggtt_offset = i915_ggtt_offset(vma) / I915_GTT_PAGE_SIZE;
        struct i915_page_table *pt;
        unsigned int pde;

        ppgtt->base.pd->base.ggtt_offset = ggtt_offset * sizeof(gen6_pte_t);
        ppgtt->pd_addr = (gen6_pte_t __iomem *)ggtt->gsm + ggtt_offset;

        gen6_for_all_pdes(pt, ppgtt->base.pd, pde)
                gen6_write_pde(ppgtt, pde, pt);

        mark_tlbs_dirty(&ppgtt->base);
        gen6_ggtt_invalidate(ppgtt->base.vm.i915);

        return 0;
}

static void pd_vma_unbind(struct i915_vma *vma)
{
        struct gen6_ppgtt *ppgtt = vma->private;
        struct i915_page_directory * const pd = ppgtt->base.pd;
        struct i915_page_table * const scratch_pt = ppgtt->base.vm.scratch_pt;
        struct i915_page_table *pt;
        unsigned int pde;

        if (!ppgtt->scan_for_unused_pt)
                return;

        /* Free all no longer used page tables */
        gen6_for_all_pdes(pt, ppgtt->base.pd, pde) {
                if (atomic_read(&pt->used) || pt == scratch_pt)
                        continue;

                free_pt(&ppgtt->base.vm, pt);
                pd->entry[pde] = scratch_pt;
        }

        ppgtt->scan_for_unused_pt = false;
}

static const struct i915_vma_ops pd_vma_ops = {
        .set_pages = pd_vma_set_pages,
        .clear_pages = pd_vma_clear_pages,
        .bind_vma = pd_vma_bind,
        .unbind_vma = pd_vma_unbind,
};

static struct i915_vma *pd_vma_create(struct gen6_ppgtt *ppgtt, int size)
{
        struct drm_i915_private *i915 = ppgtt->base.vm.i915;
        struct i915_ggtt *ggtt = &i915->ggtt;
        struct i915_vma *vma;

        GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
        GEM_BUG_ON(size > ggtt->vm.total);

        vma = i915_vma_alloc();
        if (!vma)
                return ERR_PTR(-ENOMEM);

        i915_active_init(i915, &vma->active, NULL);
        INIT_ACTIVE_REQUEST(&vma->last_fence);

        vma->vm = &ggtt->vm;
        vma->ops = &pd_vma_ops;
        vma->private = ppgtt;

        vma->size = size;
        vma->fence_size = size;
        vma->flags = I915_VMA_GGTT;
        vma->ggtt_view.type = I915_GGTT_VIEW_ROTATED; /* prevent fencing */

        INIT_LIST_HEAD(&vma->obj_link);
        INIT_LIST_HEAD(&vma->closed_link);

        mutex_lock(&vma->vm->mutex);
        list_add(&vma->vm_link, &vma->vm->unbound_list);
        mutex_unlock(&vma->vm->mutex);

        return vma;
}

int gen6_ppgtt_pin(struct i915_ppgtt *base)
{
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(base);
        int err;

        GEM_BUG_ON(ppgtt->base.vm.closed);

        /*
         * Workaround the limited maximum vma->pin_count and the aliasing_ppgtt
         * which will be pinned into every active context.
         * (When vma->pin_count becomes atomic, I expect we will naturally
         * need a larger, unpacked, type and kill this redundancy.)
         */
        if (ppgtt->pin_count++)
                return 0;

        /*
         * PPGTT PDEs reside in the GGTT and consists of 512 entries. The
         * allocator works in address space sizes, so it's multiplied by page
         * size. We allocate at the top of the GTT to avoid fragmentation.
         */
        err = i915_vma_pin(ppgtt->vma,
                           0, GEN6_PD_ALIGN,
                           PIN_GLOBAL | PIN_HIGH);
        if (err)
                goto unpin;

        return 0;

unpin:
        ppgtt->pin_count = 0;
        return err;
}

void gen6_ppgtt_unpin(struct i915_ppgtt *base)
{
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(base);

        GEM_BUG_ON(!ppgtt->pin_count);
        if (--ppgtt->pin_count)
                return;

        i915_vma_unpin(ppgtt->vma);
}

void gen6_ppgtt_unpin_all(struct i915_ppgtt *base)
{
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(base);

        if (!ppgtt->pin_count)
                return;

        ppgtt->pin_count = 0;
        i915_vma_unpin(ppgtt->vma);
}

static struct i915_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
{
        struct i915_ggtt * const ggtt = &i915->ggtt;
        struct gen6_ppgtt *ppgtt;
        int err;

        ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
        if (!ppgtt)
                return ERR_PTR(-ENOMEM);

        ppgtt_init(i915, &ppgtt->base);

        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;
        ppgtt->base.vm.cleanup = gen6_ppgtt_cleanup;

        ppgtt->base.vm.pte_encode = ggtt->vm.pte_encode;

        ppgtt->work = kmalloc(sizeof(*ppgtt->work), GFP_KERNEL);
        if (!ppgtt->work) {
                err = -ENOMEM;
                goto err_free;
        }

        ppgtt->base.pd = __alloc_pd();
        if (!ppgtt->base.pd) {
                err = -ENOMEM;
                goto err_work;
        }

        err = gen6_ppgtt_init_scratch(ppgtt);
        if (err)
                goto err_pd;

        ppgtt->vma = pd_vma_create(ppgtt, GEN6_PD_SIZE);
        if (IS_ERR(ppgtt->vma)) {
                err = PTR_ERR(ppgtt->vma);
                goto err_scratch;
        }

        return &ppgtt->base;

err_scratch:
        gen6_ppgtt_free_scratch(&ppgtt->base.vm);
err_pd:
        kfree(ppgtt->base.pd);
err_work:
        kfree(ppgtt->work);
err_free:
        kfree(ppgtt);
        return ERR_PTR(err);
}

static void gtt_write_workarounds(struct drm_i915_private *dev_priv)
{
        /* 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(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_BDW);
        else if (IS_CHERRYVIEW(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_CHV);
        else if (IS_GEN9_LP(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_BXT);
        else if (INTEL_GEN(dev_priv) >= 9)
                I915_WRITE(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(dev_priv, I915_GTT_PAGE_SIZE_64K) &&
            INTEL_GEN(dev_priv) <= 10)
                I915_WRITE(GEN8_GAMW_ECO_DEV_RW_IA,
                           I915_READ(GEN8_GAMW_ECO_DEV_RW_IA) |
                           GAMW_ECO_ENABLE_64K_IPS_FIELD);
}

int i915_ppgtt_init_hw(struct drm_i915_private *dev_priv)
{
        gtt_write_workarounds(dev_priv);

        if (IS_GEN(dev_priv, 6))
                gen6_ppgtt_enable(dev_priv);
        else if (IS_GEN(dev_priv, 7))
                gen7_ppgtt_enable(dev_priv);

        return 0;
}

static struct i915_ppgtt *
__ppgtt_create(struct drm_i915_private *i915)
{
        if (INTEL_GEN(i915) < 8)
                return gen6_ppgtt_create(i915);
        else
                return gen8_ppgtt_create(i915);
}

struct i915_ppgtt *
i915_ppgtt_create(struct drm_i915_private *i915)
{
        struct i915_ppgtt *ppgtt;

        ppgtt = __ppgtt_create(i915);
        if (IS_ERR(ppgtt))
                return ppgtt;

        trace_i915_ppgtt_create(&ppgtt->vm);

        return ppgtt;
}

static void ppgtt_destroy_vma(struct i915_address_space *vm)
{
        struct list_head *phases[] = {
                &vm->bound_list,
                &vm->unbound_list,
                NULL,
        }, **phase;

        vm->closed = true;
        for (phase = phases; *phase; phase++) {
                struct i915_vma *vma, *vn;

                list_for_each_entry_safe(vma, vn, *phase, vm_link)
                        i915_vma_destroy(vma);
        }
}

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);

        ppgtt_destroy_vma(vm);

        GEM_BUG_ON(!list_empty(&vm->bound_list));
        GEM_BUG_ON(!list_empty(&vm->unbound_list));

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

        kfree(vm);
}

/* Certain Gen5 chipsets require require idling the GPU before
 * unmapping anything from the GTT when VT-d is enabled.
 */
static bool needs_idle_maps(struct drm_i915_private *dev_priv)
{
        /* Query intel_iommu to see if we need the workaround. Presumably that
         * was loaded first.
         */
        return IS_GEN(dev_priv, 5) && IS_MOBILE(dev_priv) && intel_vtd_active();
}

void i915_gem_suspend_gtt_mappings(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;

        /* Don't bother messing with faults pre GEN6 as we have little
         * documentation supporting that it's a good idea.
         */
        if (INTEL_GEN(dev_priv) < 6)
                return;

        i915_check_and_clear_faults(dev_priv);

        ggtt->vm.clear_range(&ggtt->vm, 0, ggtt->vm.total);

        i915_ggtt_invalidate(dev_priv);
}

int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
                               struct sg_table *pages)
{
        do {
                if (dma_map_sg_attrs(&obj->base.dev->pdev->dev,
                                     pages->sgl, pages->nents,
                                     PCI_DMA_BIDIRECTIONAL,
                                     DMA_ATTR_NO_WARN))
                        return 0;

                /*
                 * If the DMA remap fails, one cause can be that we have
                 * too many objects pinned in a small remapping table,
                 * such as swiotlb. Incrementally purge all other objects and
                 * try again - if there are no more pages to remove from
                 * the DMA remapper, i915_gem_shrink will return 0.
                 */
                GEM_BUG_ON(obj->mm.pages == pages);
        } while (i915_gem_shrink(to_i915(obj->base.dev),
                                 obj->base.size >> PAGE_SHIFT, NULL,
                                 I915_SHRINK_BOUND |
                                 I915_SHRINK_UNBOUND));

        return -ENOSPC;
}

static void gen8_set_pte(void __iomem *addr, gen8_pte_t pte)
{
        writeq(pte, addr);
}

static void gen8_ggtt_insert_page(struct i915_address_space *vm,
                                  dma_addr_t addr,
                                  u64 offset,
                                  enum i915_cache_level level,
                                  u32 unused)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        gen8_pte_t __iomem *pte =
                (gen8_pte_t __iomem *)ggtt->gsm + offset / I915_GTT_PAGE_SIZE;

        gen8_set_pte(pte, gen8_pte_encode(addr, level, 0));

        ggtt->invalidate(vm->i915);
}

static void gen8_ggtt_insert_entries(struct i915_address_space *vm,
                                     struct i915_vma *vma,
                                     enum i915_cache_level level,
                                     u32 flags)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        struct sgt_iter sgt_iter;
        gen8_pte_t __iomem *gtt_entries;
        const gen8_pte_t pte_encode = gen8_pte_encode(0, level, 0);
        dma_addr_t addr;

        /*
         * Note that we ignore PTE_READ_ONLY here. The caller must be careful
         * not to allow the user to override access to a read only page.
         */

        gtt_entries = (gen8_pte_t __iomem *)ggtt->gsm;
        gtt_entries += vma->node.start / I915_GTT_PAGE_SIZE;
        for_each_sgt_dma(addr, sgt_iter, vma->pages)
                gen8_set_pte(gtt_entries++, pte_encode | addr);

        /*
         * We want to flush the TLBs only after we're certain all the PTE
         * updates have finished.
         */
        ggtt->invalidate(vm->i915);
}

static void gen6_ggtt_insert_page(struct i915_address_space *vm,
                                  dma_addr_t addr,
                                  u64 offset,
                                  enum i915_cache_level level,
                                  u32 flags)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        gen6_pte_t __iomem *pte =
                (gen6_pte_t __iomem *)ggtt->gsm + offset / I915_GTT_PAGE_SIZE;

        iowrite32(vm->pte_encode(addr, level, flags), pte);

        ggtt->invalidate(vm->i915);
}

/*
 * Binds an object into the global gtt with the specified cache level. The object
 * will be accessible to the GPU via commands whose operands reference offsets
 * within the global GTT as well as accessible by the GPU through the GMADR
 * mapped BAR (dev_priv->mm.gtt->gtt).
 */
static void gen6_ggtt_insert_entries(struct i915_address_space *vm,
                                     struct i915_vma *vma,
                                     enum i915_cache_level level,
                                     u32 flags)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        gen6_pte_t __iomem *entries = (gen6_pte_t __iomem *)ggtt->gsm;
        unsigned int i = vma->node.start / I915_GTT_PAGE_SIZE;
        struct sgt_iter iter;
        dma_addr_t addr;
        for_each_sgt_dma(addr, iter, vma->pages)
                iowrite32(vm->pte_encode(addr, level, flags), &entries[i++]);

        /*
         * We want to flush the TLBs only after we're certain all the PTE
         * updates have finished.
         */
        ggtt->invalidate(vm->i915);
}

static void nop_clear_range(struct i915_address_space *vm,
                            u64 start, u64 length)
{
}

static void gen8_ggtt_clear_range(struct i915_address_space *vm,
                                  u64 start, u64 length)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        unsigned first_entry = start / I915_GTT_PAGE_SIZE;
        unsigned num_entries = length / I915_GTT_PAGE_SIZE;
        const gen8_pte_t scratch_pte = vm->scratch_pte;
        gen8_pte_t __iomem *gtt_base =
                (gen8_pte_t __iomem *)ggtt->gsm + first_entry;
        const int max_entries = ggtt_total_entries(ggtt) - first_entry;
        int i;

        if (WARN(num_entries > max_entries,
                 "First entry = %d; Num entries = %d (max=%d)\n",
                 first_entry, num_entries, max_entries))
                num_entries = max_entries;

        for (i = 0; i < num_entries; i++)
                gen8_set_pte(&gtt_base[i], scratch_pte);
}

static void bxt_vtd_ggtt_wa(struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = vm->i915;

        /*
         * Make sure the internal GAM fifo has been cleared of all GTT
         * writes before exiting stop_machine(). This guarantees that
         * any aperture accesses waiting to start in another process
         * cannot back up behind the GTT writes causing a hang.
         * The register can be any arbitrary GAM register.
         */
        POSTING_READ(GFX_FLSH_CNTL_GEN6);
}

struct insert_page {
        struct i915_address_space *vm;
        dma_addr_t addr;
        u64 offset;
        enum i915_cache_level level;
};

static int bxt_vtd_ggtt_insert_page__cb(void *_arg)
{
        struct insert_page *arg = _arg;

        gen8_ggtt_insert_page(arg->vm, arg->addr, arg->offset, arg->level, 0);
        bxt_vtd_ggtt_wa(arg->vm);

        return 0;
}

static void bxt_vtd_ggtt_insert_page__BKL(struct i915_address_space *vm,
                                          dma_addr_t addr,
                                          u64 offset,
                                          enum i915_cache_level level,
                                          u32 unused)
{
        struct insert_page arg = { vm, addr, offset, level };

        stop_machine(bxt_vtd_ggtt_insert_page__cb, &arg, NULL);
}

struct insert_entries {
        struct i915_address_space *vm;
        struct i915_vma *vma;
        enum i915_cache_level level;
        u32 flags;
};

static int bxt_vtd_ggtt_insert_entries__cb(void *_arg)
{
        struct insert_entries *arg = _arg;

        gen8_ggtt_insert_entries(arg->vm, arg->vma, arg->level, arg->flags);
        bxt_vtd_ggtt_wa(arg->vm);

        return 0;
}

static void bxt_vtd_ggtt_insert_entries__BKL(struct i915_address_space *vm,
                                             struct i915_vma *vma,
                                             enum i915_cache_level level,
                                             u32 flags)
{
        struct insert_entries arg = { vm, vma, level, flags };

        stop_machine(bxt_vtd_ggtt_insert_entries__cb, &arg, NULL);
}

struct clear_range {
        struct i915_address_space *vm;
        u64 start;
        u64 length;
};

static int bxt_vtd_ggtt_clear_range__cb(void *_arg)
{
        struct clear_range *arg = _arg;

        gen8_ggtt_clear_range(arg->vm, arg->start, arg->length);
        bxt_vtd_ggtt_wa(arg->vm);

        return 0;
}

static void bxt_vtd_ggtt_clear_range__BKL(struct i915_address_space *vm,
                                          u64 start,
                                          u64 length)
{
        struct clear_range arg = { vm, start, length };

        stop_machine(bxt_vtd_ggtt_clear_range__cb, &arg, NULL);
}

static void gen6_ggtt_clear_range(struct i915_address_space *vm,
                                  u64 start, u64 length)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        unsigned first_entry = start / I915_GTT_PAGE_SIZE;
        unsigned num_entries = length / I915_GTT_PAGE_SIZE;
        gen6_pte_t scratch_pte, __iomem *gtt_base =
                (gen6_pte_t __iomem *)ggtt->gsm + first_entry;
        const int max_entries = ggtt_total_entries(ggtt) - first_entry;
        int i;

        if (WARN(num_entries > max_entries,
                 "First entry = %d; Num entries = %d (max=%d)\n",
                 first_entry, num_entries, max_entries))
                num_entries = max_entries;

        scratch_pte = vm->scratch_pte;

        for (i = 0; i < num_entries; i++)
                iowrite32(scratch_pte, &gtt_base[i]);
}

static void i915_ggtt_insert_page(struct i915_address_space *vm,
                                  dma_addr_t addr,
                                  u64 offset,
                                  enum i915_cache_level cache_level,
                                  u32 unused)
{
        unsigned int flags = (cache_level == I915_CACHE_NONE) ?
                AGP_USER_MEMORY : AGP_USER_CACHED_MEMORY;

        intel_gtt_insert_page(addr, offset >> PAGE_SHIFT, flags);
}

static void i915_ggtt_insert_entries(struct i915_address_space *vm,
                                     struct i915_vma *vma,
                                     enum i915_cache_level cache_level,
                                     u32 unused)
{
        unsigned int flags = (cache_level == I915_CACHE_NONE) ?
                AGP_USER_MEMORY : AGP_USER_CACHED_MEMORY;

        intel_gtt_insert_sg_entries(vma->pages, vma->node.start >> PAGE_SHIFT,
                                    flags);
}

static void i915_ggtt_clear_range(struct i915_address_space *vm,
                                  u64 start, u64 length)
{
        intel_gtt_clear_range(start >> PAGE_SHIFT, length >> PAGE_SHIFT);
}

static int ggtt_bind_vma(struct i915_vma *vma,
                         enum i915_cache_level cache_level,
                         u32 flags)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        struct drm_i915_gem_object *obj = vma->obj;
        intel_wakeref_t wakeref;
        u32 pte_flags;

        /* Applicable to VLV (gen8+ do not support RO in the GGTT) */
        pte_flags = 0;
        if (i915_gem_object_is_readonly(obj))
                pte_flags |= PTE_READ_ONLY;

        with_intel_runtime_pm(&i915->runtime_pm, wakeref)
                vma->vm->insert_entries(vma->vm, vma, cache_level, pte_flags);

        vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;

        /*
         * Without aliasing PPGTT there's no difference between
         * GLOBAL/LOCAL_BIND, it's all the same ptes. Hence unconditionally
         * upgrade to both bound if we bind either to avoid double-binding.
         */
        vma->flags |= I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;

        return 0;
}

static void ggtt_unbind_vma(struct i915_vma *vma)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        intel_wakeref_t wakeref;

        with_intel_runtime_pm(&i915->runtime_pm, wakeref)
                vma->vm->clear_range(vma->vm, vma->node.start, vma->size);
}

static int aliasing_gtt_bind_vma(struct i915_vma *vma,
                                 enum i915_cache_level cache_level,
                                 u32 flags)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        u32 pte_flags;
        int ret;

        /* Currently applicable only to VLV */
        pte_flags = 0;
        if (i915_gem_object_is_readonly(vma->obj))
                pte_flags |= PTE_READ_ONLY;

        if (flags & I915_VMA_LOCAL_BIND) {
                struct i915_ppgtt *appgtt = i915->mm.aliasing_ppgtt;

                if (!(vma->flags & I915_VMA_LOCAL_BIND)) {
                        ret = appgtt->vm.allocate_va_range(&appgtt->vm,
                                                           vma->node.start,
                                                           vma->size);
                        if (ret)
                                return ret;
                }

                appgtt->vm.insert_entries(&appgtt->vm, vma, cache_level,
                                          pte_flags);
        }

        if (flags & I915_VMA_GLOBAL_BIND) {
                intel_wakeref_t wakeref;

                with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
                        vma->vm->insert_entries(vma->vm, vma,
                                                cache_level, pte_flags);
                }
        }

        return 0;
}

static void aliasing_gtt_unbind_vma(struct i915_vma *vma)
{
        struct drm_i915_private *i915 = vma->vm->i915;

        if (vma->flags & I915_VMA_GLOBAL_BIND) {
                struct i915_address_space *vm = vma->vm;
                intel_wakeref_t wakeref;

                with_intel_runtime_pm(&i915->runtime_pm, wakeref)
                        vm->clear_range(vm, vma->node.start, vma->size);
        }

        if (vma->flags & I915_VMA_LOCAL_BIND) {
                struct i915_address_space *vm = &i915->mm.aliasing_ppgtt->vm;

                vm->clear_range(vm, vma->node.start, vma->size);
        }
}

void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
                               struct sg_table *pages)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        struct device *kdev = &dev_priv->drm.pdev->dev;
        struct i915_ggtt *ggtt = &dev_priv->ggtt;

        if (unlikely(ggtt->do_idle_maps)) {
                if (i915_gem_wait_for_idle(dev_priv, 0, MAX_SCHEDULE_TIMEOUT)) {
                        DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");
                        /* Wait a bit, in hopes it avoids the hang */
                        udelay(10);
                }
        }

        dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL);
}

static int ggtt_set_pages(struct i915_vma *vma)
{
        int ret;

        GEM_BUG_ON(vma->pages);

        ret = i915_get_ggtt_vma_pages(vma);
        if (ret)
                return ret;

        vma->page_sizes = vma->obj->mm.page_sizes;

        return 0;
}

static void i915_gtt_color_adjust(const struct drm_mm_node *node,
                                  unsigned long color,
                                  u64 *start,
                                  u64 *end)
{
        if (node->allocated && node->color != color)
                *start += I915_GTT_PAGE_SIZE;

        /* Also leave a space between the unallocated reserved node after the
         * GTT and any objects within the GTT, i.e. we use the color adjustment
         * to insert a guard page to prevent prefetches crossing over the
         * GTT boundary.
         */
        node = list_next_entry(node, node_list);
        if (node->color != color)
                *end -= I915_GTT_PAGE_SIZE;
}

static int init_aliasing_ppgtt(struct drm_i915_private *i915)
{
        struct i915_ggtt *ggtt = &i915->ggtt;
        struct i915_ppgtt *ppgtt;
        int err;

        ppgtt = i915_ppgtt_create(i915);
        if (IS_ERR(ppgtt))
                return PTR_ERR(ppgtt);

        if (GEM_WARN_ON(ppgtt->vm.total < ggtt->vm.total)) {
                err = -ENODEV;
                goto err_ppgtt;
        }

        /*
         * Note we only pre-allocate as far as the end of the global
         * GTT. On 48b / 4-level page-tables, the difference is very,
         * very significant! We have to preallocate as GVT/vgpu does
         * not like the page directory disappearing.
         */
        err = ppgtt->vm.allocate_va_range(&ppgtt->vm, 0, ggtt->vm.total);
        if (err)
                goto err_ppgtt;

        i915->mm.aliasing_ppgtt = ppgtt;

        GEM_BUG_ON(ggtt->vm.vma_ops.bind_vma != ggtt_bind_vma);
        ggtt->vm.vma_ops.bind_vma = aliasing_gtt_bind_vma;

        GEM_BUG_ON(ggtt->vm.vma_ops.unbind_vma != ggtt_unbind_vma);
        ggtt->vm.vma_ops.unbind_vma = aliasing_gtt_unbind_vma;

        return 0;

err_ppgtt:
        i915_vm_put(&ppgtt->vm);
        return err;
}

static void fini_aliasing_ppgtt(struct drm_i915_private *i915)
{
        struct i915_ggtt *ggtt = &i915->ggtt;
        struct i915_ppgtt *ppgtt;

        ppgtt = fetch_and_zero(&i915->mm.aliasing_ppgtt);
        if (!ppgtt)
                return;

        i915_vm_put(&ppgtt->vm);

        ggtt->vm.vma_ops.bind_vma   = ggtt_bind_vma;
        ggtt->vm.vma_ops.unbind_vma = ggtt_unbind_vma;
}

static int ggtt_reserve_guc_top(struct i915_ggtt *ggtt)
{
        u64 size;
        int ret;

        if (!USES_GUC(ggtt->vm.i915))
                return 0;

        GEM_BUG_ON(ggtt->vm.total <= GUC_GGTT_TOP);
        size = ggtt->vm.total - GUC_GGTT_TOP;

        ret = i915_gem_gtt_reserve(&ggtt->vm, &ggtt->uc_fw, size,
                                   GUC_GGTT_TOP, I915_COLOR_UNEVICTABLE,
                                   PIN_NOEVICT);
        if (ret)
                DRM_DEBUG_DRIVER("Failed to reserve top of GGTT for GuC\n");

        return ret;
}

static void ggtt_release_guc_top(struct i915_ggtt *ggtt)
{
        if (drm_mm_node_allocated(&ggtt->uc_fw))
                drm_mm_remove_node(&ggtt->uc_fw);
}

int i915_gem_init_ggtt(struct drm_i915_private *dev_priv)
{
        /* Let GEM Manage all of the aperture.
         *
         * However, leave one page at the end still bound to the scratch page.
         * There are a number of places where the hardware apparently prefetches
         * past the end of the object, and we've seen multiple hangs with the
         * GPU head pointer stuck in a batchbuffer bound at the last page of the
         * aperture.  One page should be enough to keep any prefetching inside
         * of the aperture.
         */
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        unsigned long hole_start, hole_end;
        struct drm_mm_node *entry;
        int ret;

        /*
         * GuC requires all resources that we're sharing with it to be placed in
         * non-WOPCM memory. If GuC is not present or not in use we still need a
         * small bias as ring wraparound at offset 0 sometimes hangs. No idea
         * why.
         */
        ggtt->pin_bias = max_t(u32, I915_GTT_PAGE_SIZE,
                               intel_wopcm_guc_size(&dev_priv->wopcm));

        ret = intel_vgt_balloon(dev_priv);
        if (ret)
                return ret;

        /* Reserve a mappable slot for our lockless error capture */
        ret = drm_mm_insert_node_in_range(&ggtt->vm.mm, &ggtt->error_capture,
                                          PAGE_SIZE, 0, I915_COLOR_UNEVICTABLE,
                                          0, ggtt->mappable_end,
                                          DRM_MM_INSERT_LOW);
        if (ret)
                return ret;

        /*
         * The upper portion of the GuC address space has a sizeable hole
         * (several MB) that is inaccessible by GuC. Reserve this range within
         * GGTT as it can comfortably hold GuC/HuC firmware images.
         */
        ret = ggtt_reserve_guc_top(ggtt);
        if (ret)
                goto err_reserve;

        /* Clear any non-preallocated blocks */
        drm_mm_for_each_hole(entry, &ggtt->vm.mm, hole_start, hole_end) {
                DRM_DEBUG_KMS("clearing unused GTT space: [%lx, %lx]\n",
                              hole_start, hole_end);
                ggtt->vm.clear_range(&ggtt->vm, hole_start,
                                     hole_end - hole_start);
        }

        /* And finally clear the reserved guard page */
        ggtt->vm.clear_range(&ggtt->vm, ggtt->vm.total - PAGE_SIZE, PAGE_SIZE);

        if (INTEL_PPGTT(dev_priv) == INTEL_PPGTT_ALIASING) {
                ret = init_aliasing_ppgtt(dev_priv);
                if (ret)
                        goto err_appgtt;
        }

        return 0;

err_appgtt:
        ggtt_release_guc_top(ggtt);
err_reserve:
        drm_mm_remove_node(&ggtt->error_capture);
        return ret;
}

/**
 * i915_ggtt_cleanup_hw - Clean up GGTT hardware initialization
 * @dev_priv: i915 device
 */
void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct i915_vma *vma, *vn;
        struct pagevec *pvec;

        ggtt->vm.closed = true;

        mutex_lock(&dev_priv->drm.struct_mutex);
        fini_aliasing_ppgtt(dev_priv);

        list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link)
                WARN_ON(i915_vma_unbind(vma));

        if (drm_mm_node_allocated(&ggtt->error_capture))
                drm_mm_remove_node(&ggtt->error_capture);

        ggtt_release_guc_top(ggtt);

        if (drm_mm_initialized(&ggtt->vm.mm)) {
                intel_vgt_deballoon(dev_priv);
                i915_address_space_fini(&ggtt->vm);
        }

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

        pvec = &dev_priv->mm.wc_stash.pvec;
        if (pvec->nr) {
                set_pages_array_wb(pvec->pages, pvec->nr);
                __pagevec_release(pvec);
        }

        mutex_unlock(&dev_priv->drm.struct_mutex);

        arch_phys_wc_del(ggtt->mtrr);
        io_mapping_fini(&ggtt->iomap);

        i915_gem_cleanup_stolen(dev_priv);
}

static unsigned int gen6_get_total_gtt_size(u16 snb_gmch_ctl)
{
        snb_gmch_ctl >>= SNB_GMCH_GGMS_SHIFT;
        snb_gmch_ctl &= SNB_GMCH_GGMS_MASK;
        return snb_gmch_ctl << 20;
}

static unsigned int gen8_get_total_gtt_size(u16 bdw_gmch_ctl)
{
        bdw_gmch_ctl >>= BDW_GMCH_GGMS_SHIFT;
        bdw_gmch_ctl &= BDW_GMCH_GGMS_MASK;
        if (bdw_gmch_ctl)
                bdw_gmch_ctl = 1 << bdw_gmch_ctl;

#ifdef CONFIG_X86_32
        /* Limit 32b platforms to a 2GB GGTT: 4 << 20 / pte size * I915_GTT_PAGE_SIZE */
        if (bdw_gmch_ctl > 4)
                bdw_gmch_ctl = 4;
#endif

        return bdw_gmch_ctl << 20;
}

static unsigned int chv_get_total_gtt_size(u16 gmch_ctrl)
{
        gmch_ctrl >>= SNB_GMCH_GGMS_SHIFT;
        gmch_ctrl &= SNB_GMCH_GGMS_MASK;

        if (gmch_ctrl)
                return 1 << (20 + gmch_ctrl);

        return 0;
}

static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size)
{
        struct drm_i915_private *dev_priv = ggtt->vm.i915;
        struct pci_dev *pdev = dev_priv->drm.pdev;
        phys_addr_t phys_addr;
        int ret;

        /* For Modern GENs the PTEs and register space are split in the BAR */
        phys_addr = pci_resource_start(pdev, 0) + pci_resource_len(pdev, 0) / 2;

        /*
         * On BXT+/CNL+ writes larger than 64 bit to the GTT pagetable range
         * will be dropped. For WC mappings in general we have 64 byte burst
         * writes when the WC buffer is flushed, so we can't use it, but have to