GNU Linux-libre 6.8.7-gnu

[releases.git] / arch / arm64 / kvm / mmu.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
 */

#include <linux/mman.h>
#include <linux/kvm_host.h>
#include <linux/io.h>
#include <linux/hugetlb.h>
#include <linux/sched/signal.h>
#include <trace/events/kvm.h>
#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_pgtable.h>
#include <asm/kvm_ras.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/virt.h>

#include "trace.h"

static struct kvm_pgtable *hyp_pgtable;
static DEFINE_MUTEX(kvm_hyp_pgd_mutex);

static unsigned long __ro_after_init hyp_idmap_start;
static unsigned long __ro_after_init hyp_idmap_end;
static phys_addr_t __ro_after_init hyp_idmap_vector;

static unsigned long __ro_after_init io_map_base;

static phys_addr_t __stage2_range_addr_end(phys_addr_t addr, phys_addr_t end,
                                           phys_addr_t size)
{
        phys_addr_t boundary = ALIGN_DOWN(addr + size, size);

        return (boundary - 1 < end - 1) ? boundary : end;
}

static phys_addr_t stage2_range_addr_end(phys_addr_t addr, phys_addr_t end)
{
        phys_addr_t size = kvm_granule_size(KVM_PGTABLE_MIN_BLOCK_LEVEL);

        return __stage2_range_addr_end(addr, end, size);
}

/*
 * Release kvm_mmu_lock periodically if the memory region is large. Otherwise,
 * we may see kernel panics with CONFIG_DETECT_HUNG_TASK,
 * CONFIG_LOCKUP_DETECTOR, CONFIG_LOCKDEP. Additionally, holding the lock too
 * long will also starve other vCPUs. We have to also make sure that the page
 * tables are not freed while we released the lock.
 */
static int stage2_apply_range(struct kvm_s2_mmu *mmu, phys_addr_t addr,
                              phys_addr_t end,
                              int (*fn)(struct kvm_pgtable *, u64, u64),
                              bool resched)
{
        struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
        int ret;
        u64 next;

        do {
                struct kvm_pgtable *pgt = mmu->pgt;
                if (!pgt)
                        return -EINVAL;

                next = stage2_range_addr_end(addr, end);
                ret = fn(pgt, addr, next - addr);
                if (ret)
                        break;

                if (resched && next != end)
                        cond_resched_rwlock_write(&kvm->mmu_lock);
        } while (addr = next, addr != end);

        return ret;
}

#define stage2_apply_range_resched(mmu, addr, end, fn)                  \
        stage2_apply_range(mmu, addr, end, fn, true)

/*
 * Get the maximum number of page-tables pages needed to split a range
 * of blocks into PAGE_SIZE PTEs. It assumes the range is already
 * mapped at level 2, or at level 1 if allowed.
 */
static int kvm_mmu_split_nr_page_tables(u64 range)
{
        int n = 0;

        if (KVM_PGTABLE_MIN_BLOCK_LEVEL < 2)
                n += DIV_ROUND_UP(range, PUD_SIZE);
        n += DIV_ROUND_UP(range, PMD_SIZE);
        return n;
}

static bool need_split_memcache_topup_or_resched(struct kvm *kvm)
{
        struct kvm_mmu_memory_cache *cache;
        u64 chunk_size, min;

        if (need_resched() || rwlock_needbreak(&kvm->mmu_lock))
                return true;

        chunk_size = kvm->arch.mmu.split_page_chunk_size;
        min = kvm_mmu_split_nr_page_tables(chunk_size);
        cache = &kvm->arch.mmu.split_page_cache;
        return kvm_mmu_memory_cache_nr_free_objects(cache) < min;
}

static int kvm_mmu_split_huge_pages(struct kvm *kvm, phys_addr_t addr,
                                    phys_addr_t end)
{
        struct kvm_mmu_memory_cache *cache;
        struct kvm_pgtable *pgt;
        int ret, cache_capacity;
        u64 next, chunk_size;

        lockdep_assert_held_write(&kvm->mmu_lock);

        chunk_size = kvm->arch.mmu.split_page_chunk_size;
        cache_capacity = kvm_mmu_split_nr_page_tables(chunk_size);

        if (chunk_size == 0)
                return 0;

        cache = &kvm->arch.mmu.split_page_cache;

        do {
                if (need_split_memcache_topup_or_resched(kvm)) {
                        write_unlock(&kvm->mmu_lock);
                        cond_resched();
                        /* Eager page splitting is best-effort. */
                        ret = __kvm_mmu_topup_memory_cache(cache,
                                                           cache_capacity,
                                                           cache_capacity);
                        write_lock(&kvm->mmu_lock);
                        if (ret)
                                break;
                }

                pgt = kvm->arch.mmu.pgt;
                if (!pgt)
                        return -EINVAL;

                next = __stage2_range_addr_end(addr, end, chunk_size);
                ret = kvm_pgtable_stage2_split(pgt, addr, next - addr, cache);
                if (ret)
                        break;
        } while (addr = next, addr != end);

        return ret;
}

static bool memslot_is_logging(struct kvm_memory_slot *memslot)
{
        return memslot->dirty_bitmap && !(memslot->flags & KVM_MEM_READONLY);
}

/**
 * kvm_arch_flush_remote_tlbs() - flush all VM TLB entries for v7/8
 * @kvm:        pointer to kvm structure.
 *
 * Interface to HYP function to flush all VM TLB entries
 */
int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
{
        kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu);
        return 0;
}

int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
                                      gfn_t gfn, u64 nr_pages)
{
        kvm_tlb_flush_vmid_range(&kvm->arch.mmu,
                                gfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
        return 0;
}

static bool kvm_is_device_pfn(unsigned long pfn)
{
        return !pfn_is_map_memory(pfn);
}

static void *stage2_memcache_zalloc_page(void *arg)
{
        struct kvm_mmu_memory_cache *mc = arg;
        void *virt;

        /* Allocated with __GFP_ZERO, so no need to zero */
        virt = kvm_mmu_memory_cache_alloc(mc);
        if (virt)
                kvm_account_pgtable_pages(virt, 1);
        return virt;
}

static void *kvm_host_zalloc_pages_exact(size_t size)
{
        return alloc_pages_exact(size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
}

static void *kvm_s2_zalloc_pages_exact(size_t size)
{
        void *virt = kvm_host_zalloc_pages_exact(size);

        if (virt)
                kvm_account_pgtable_pages(virt, (size >> PAGE_SHIFT));
        return virt;
}

static void kvm_s2_free_pages_exact(void *virt, size_t size)
{
        kvm_account_pgtable_pages(virt, -(size >> PAGE_SHIFT));
        free_pages_exact(virt, size);
}

static struct kvm_pgtable_mm_ops kvm_s2_mm_ops;

static void stage2_free_unlinked_table_rcu_cb(struct rcu_head *head)
{
        struct page *page = container_of(head, struct page, rcu_head);
        void *pgtable = page_to_virt(page);
        s8 level = page_private(page);

        kvm_pgtable_stage2_free_unlinked(&kvm_s2_mm_ops, pgtable, level);
}

static void stage2_free_unlinked_table(void *addr, s8 level)
{
        struct page *page = virt_to_page(addr);

        set_page_private(page, (unsigned long)level);
        call_rcu(&page->rcu_head, stage2_free_unlinked_table_rcu_cb);
}

static void kvm_host_get_page(void *addr)
{
        get_page(virt_to_page(addr));
}

static void kvm_host_put_page(void *addr)
{
        put_page(virt_to_page(addr));
}

static void kvm_s2_put_page(void *addr)
{
        struct page *p = virt_to_page(addr);
        /* Dropping last refcount, the page will be freed */
        if (page_count(p) == 1)
                kvm_account_pgtable_pages(addr, -1);
        put_page(p);
}

static int kvm_host_page_count(void *addr)
{
        return page_count(virt_to_page(addr));
}

static phys_addr_t kvm_host_pa(void *addr)
{
        return __pa(addr);
}

static void *kvm_host_va(phys_addr_t phys)
{
        return __va(phys);
}

static void clean_dcache_guest_page(void *va, size_t size)
{
        __clean_dcache_guest_page(va, size);
}

static void invalidate_icache_guest_page(void *va, size_t size)
{
        __invalidate_icache_guest_page(va, size);
}

/*
 * Unmapping vs dcache management:
 *
 * If a guest maps certain memory pages as uncached, all writes will
 * bypass the data cache and go directly to RAM.  However, the CPUs
 * can still speculate reads (not writes) and fill cache lines with
 * data.
 *
 * Those cache lines will be *clean* cache lines though, so a
 * clean+invalidate operation is equivalent to an invalidate
 * operation, because no cache lines are marked dirty.
 *
 * Those clean cache lines could be filled prior to an uncached write
 * by the guest, and the cache coherent IO subsystem would therefore
 * end up writing old data to disk.
 *
 * This is why right after unmapping a page/section and invalidating
 * the corresponding TLBs, we flush to make sure the IO subsystem will
 * never hit in the cache.
 *
 * This is all avoided on systems that have ARM64_HAS_STAGE2_FWB, as
 * we then fully enforce cacheability of RAM, no matter what the guest
 * does.
 */
/**
 * unmap_stage2_range -- Clear stage2 page table entries to unmap a range
 * @mmu:   The KVM stage-2 MMU pointer
 * @start: The intermediate physical base address of the range to unmap
 * @size:  The size of the area to unmap
 * @may_block: Whether or not we are permitted to block
 *
 * Clear a range of stage-2 mappings, lowering the various ref-counts.  Must
 * be called while holding mmu_lock (unless for freeing the stage2 pgd before
 * destroying the VM), otherwise another faulting VCPU may come in and mess
 * with things behind our backs.
 */
static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size,
                                 bool may_block)
{
        struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
        phys_addr_t end = start + size;

        lockdep_assert_held_write(&kvm->mmu_lock);
        WARN_ON(size & ~PAGE_MASK);
        WARN_ON(stage2_apply_range(mmu, start, end, kvm_pgtable_stage2_unmap,
                                   may_block));
}

static void unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size)
{
        __unmap_stage2_range(mmu, start, size, true);
}

static void stage2_flush_memslot(struct kvm *kvm,
                                 struct kvm_memory_slot *memslot)
{
        phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
        phys_addr_t end = addr + PAGE_SIZE * memslot->npages;

        stage2_apply_range_resched(&kvm->arch.mmu, addr, end, kvm_pgtable_stage2_flush);
}

/**
 * stage2_flush_vm - Invalidate cache for pages mapped in stage 2
 * @kvm: The struct kvm pointer
 *
 * Go through the stage 2 page tables and invalidate any cache lines
 * backing memory already mapped to the VM.
 */
static void stage2_flush_vm(struct kvm *kvm)
{
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;
        int idx, bkt;

        idx = srcu_read_lock(&kvm->srcu);
        write_lock(&kvm->mmu_lock);

        slots = kvm_memslots(kvm);
        kvm_for_each_memslot(memslot, bkt, slots)
                stage2_flush_memslot(kvm, memslot);

        write_unlock(&kvm->mmu_lock);
        srcu_read_unlock(&kvm->srcu, idx);
}

/**
 * free_hyp_pgds - free Hyp-mode page tables
 */
void __init free_hyp_pgds(void)
{
        mutex_lock(&kvm_hyp_pgd_mutex);
        if (hyp_pgtable) {
                kvm_pgtable_hyp_destroy(hyp_pgtable);
                kfree(hyp_pgtable);
                hyp_pgtable = NULL;
        }
        mutex_unlock(&kvm_hyp_pgd_mutex);
}

static bool kvm_host_owns_hyp_mappings(void)
{
        if (is_kernel_in_hyp_mode())
                return false;

        if (static_branch_likely(&kvm_protected_mode_initialized))
                return false;

        /*
         * This can happen at boot time when __create_hyp_mappings() is called
         * after the hyp protection has been enabled, but the static key has
         * not been flipped yet.
         */
        if (!hyp_pgtable && is_protected_kvm_enabled())
                return false;

        WARN_ON(!hyp_pgtable);

        return true;
}

int __create_hyp_mappings(unsigned long start, unsigned long size,
                          unsigned long phys, enum kvm_pgtable_prot prot)
{
        int err;

        if (WARN_ON(!kvm_host_owns_hyp_mappings()))
                return -EINVAL;

        mutex_lock(&kvm_hyp_pgd_mutex);
        err = kvm_pgtable_hyp_map(hyp_pgtable, start, size, phys, prot);
        mutex_unlock(&kvm_hyp_pgd_mutex);

        return err;
}

static phys_addr_t kvm_kaddr_to_phys(void *kaddr)
{
        if (!is_vmalloc_addr(kaddr)) {
                BUG_ON(!virt_addr_valid(kaddr));
                return __pa(kaddr);
        } else {
                return page_to_phys(vmalloc_to_page(kaddr)) +
                       offset_in_page(kaddr);
        }
}

struct hyp_shared_pfn {
        u64 pfn;
        int count;
        struct rb_node node;
};

static DEFINE_MUTEX(hyp_shared_pfns_lock);
static struct rb_root hyp_shared_pfns = RB_ROOT;

static struct hyp_shared_pfn *find_shared_pfn(u64 pfn, struct rb_node ***node,
                                              struct rb_node **parent)
{
        struct hyp_shared_pfn *this;

        *node = &hyp_shared_pfns.rb_node;
        *parent = NULL;
        while (**node) {
                this = container_of(**node, struct hyp_shared_pfn, node);
                *parent = **node;
                if (this->pfn < pfn)
                        *node = &((**node)->rb_left);
                else if (this->pfn > pfn)
                        *node = &((**node)->rb_right);
                else
                        return this;
        }

        return NULL;
}

static int share_pfn_hyp(u64 pfn)
{
        struct rb_node **node, *parent;
        struct hyp_shared_pfn *this;
        int ret = 0;

        mutex_lock(&hyp_shared_pfns_lock);
        this = find_shared_pfn(pfn, &node, &parent);
        if (this) {
                this->count++;
                goto unlock;
        }

        this = kzalloc(sizeof(*this), GFP_KERNEL);
        if (!this) {
                ret = -ENOMEM;
                goto unlock;
        }

        this->pfn = pfn;
        this->count = 1;
        rb_link_node(&this->node, parent, node);
        rb_insert_color(&this->node, &hyp_shared_pfns);
        ret = kvm_call_hyp_nvhe(__pkvm_host_share_hyp, pfn, 1);
unlock:
        mutex_unlock(&hyp_shared_pfns_lock);

        return ret;
}

static int unshare_pfn_hyp(u64 pfn)
{
        struct rb_node **node, *parent;
        struct hyp_shared_pfn *this;
        int ret = 0;

        mutex_lock(&hyp_shared_pfns_lock);
        this = find_shared_pfn(pfn, &node, &parent);
        if (WARN_ON(!this)) {
                ret = -ENOENT;
                goto unlock;
        }

        this->count--;
        if (this->count)
                goto unlock;

        rb_erase(&this->node, &hyp_shared_pfns);
        kfree(this);
        ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1);
unlock:
        mutex_unlock(&hyp_shared_pfns_lock);

        return ret;
}

int kvm_share_hyp(void *from, void *to)
{
        phys_addr_t start, end, cur;
        u64 pfn;
        int ret;

        if (is_kernel_in_hyp_mode())
                return 0;

        /*
         * The share hcall maps things in the 'fixed-offset' region of the hyp
         * VA space, so we can only share physically contiguous data-structures
         * for now.
         */
        if (is_vmalloc_or_module_addr(from) || is_vmalloc_or_module_addr(to))
                return -EINVAL;

        if (kvm_host_owns_hyp_mappings())
                return create_hyp_mappings(from, to, PAGE_HYP);

        start = ALIGN_DOWN(__pa(from), PAGE_SIZE);
        end = PAGE_ALIGN(__pa(to));
        for (cur = start; cur < end; cur += PAGE_SIZE) {
                pfn = __phys_to_pfn(cur);
                ret = share_pfn_hyp(pfn);
                if (ret)
                        return ret;
        }

        return 0;
}

void kvm_unshare_hyp(void *from, void *to)
{
        phys_addr_t start, end, cur;
        u64 pfn;

        if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from)
                return;

        start = ALIGN_DOWN(__pa(from), PAGE_SIZE);
        end = PAGE_ALIGN(__pa(to));
        for (cur = start; cur < end; cur += PAGE_SIZE) {
                pfn = __phys_to_pfn(cur);
                WARN_ON(unshare_pfn_hyp(pfn));
        }
}

/**
 * create_hyp_mappings - duplicate a kernel virtual address range in Hyp mode
 * @from:       The virtual kernel start address of the range
 * @to:         The virtual kernel end address of the range (exclusive)
 * @prot:       The protection to be applied to this range
 *
 * The same virtual address as the kernel virtual address is also used
 * in Hyp-mode mapping (modulo HYP_PAGE_OFFSET) to the same underlying
 * physical pages.
 */
int create_hyp_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
{
        phys_addr_t phys_addr;
        unsigned long virt_addr;
        unsigned long start = kern_hyp_va((unsigned long)from);
        unsigned long end = kern_hyp_va((unsigned long)to);

        if (is_kernel_in_hyp_mode())
                return 0;

        if (!kvm_host_owns_hyp_mappings())
                return -EPERM;

        start = start & PAGE_MASK;
        end = PAGE_ALIGN(end);

        for (virt_addr = start; virt_addr < end; virt_addr += PAGE_SIZE) {
                int err;

                phys_addr = kvm_kaddr_to_phys(from + virt_addr - start);
                err = __create_hyp_mappings(virt_addr, PAGE_SIZE, phys_addr,
                                            prot);
                if (err)
                        return err;
        }

        return 0;
}

static int __hyp_alloc_private_va_range(unsigned long base)
{
        lockdep_assert_held(&kvm_hyp_pgd_mutex);

        if (!PAGE_ALIGNED(base))
                return -EINVAL;

        /*
         * Verify that BIT(VA_BITS - 1) hasn't been flipped by
         * allocating the new area, as it would indicate we've
         * overflowed the idmap/IO address range.
         */
        if ((base ^ io_map_base) & BIT(VA_BITS - 1))
                return -ENOMEM;

        io_map_base = base;

        return 0;
}

/**
 * hyp_alloc_private_va_range - Allocates a private VA range.
 * @size:       The size of the VA range to reserve.
 * @haddr:      The hypervisor virtual start address of the allocation.
 *
 * The private virtual address (VA) range is allocated below io_map_base
 * and aligned based on the order of @size.
 *
 * Return: 0 on success or negative error code on failure.
 */
int hyp_alloc_private_va_range(size_t size, unsigned long *haddr)
{
        unsigned long base;
        int ret = 0;

        mutex_lock(&kvm_hyp_pgd_mutex);

        /*
         * This assumes that we have enough space below the idmap
         * page to allocate our VAs. If not, the check in
         * __hyp_alloc_private_va_range() will kick. A potential
         * alternative would be to detect that overflow and switch
         * to an allocation above the idmap.
         *
         * The allocated size is always a multiple of PAGE_SIZE.
         */
        size = PAGE_ALIGN(size);
        base = io_map_base - size;
        ret = __hyp_alloc_private_va_range(base);

        mutex_unlock(&kvm_hyp_pgd_mutex);

        if (!ret)
                *haddr = base;

        return ret;
}

static int __create_hyp_private_mapping(phys_addr_t phys_addr, size_t size,
                                        unsigned long *haddr,
                                        enum kvm_pgtable_prot prot)
{
        unsigned long addr;
        int ret = 0;

        if (!kvm_host_owns_hyp_mappings()) {
                addr = kvm_call_hyp_nvhe(__pkvm_create_private_mapping,
                                         phys_addr, size, prot);
                if (IS_ERR_VALUE(addr))
                        return addr;
                *haddr = addr;

                return 0;
        }

        size = PAGE_ALIGN(size + offset_in_page(phys_addr));
        ret = hyp_alloc_private_va_range(size, &addr);
        if (ret)
                return ret;

        ret = __create_hyp_mappings(addr, size, phys_addr, prot);
        if (ret)
                return ret;

        *haddr = addr + offset_in_page(phys_addr);
        return ret;
}

int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr)
{
        unsigned long base;
        size_t size;
        int ret;

        mutex_lock(&kvm_hyp_pgd_mutex);
        /*
         * Efficient stack verification using the PAGE_SHIFT bit implies
         * an alignment of our allocation on the order of the size.
         */
        size = PAGE_SIZE * 2;
        base = ALIGN_DOWN(io_map_base - size, size);

        ret = __hyp_alloc_private_va_range(base);

        mutex_unlock(&kvm_hyp_pgd_mutex);

        if (ret) {
                kvm_err("Cannot allocate hyp stack guard page\n");
                return ret;
        }

        /*
         * Since the stack grows downwards, map the stack to the page
         * at the higher address and leave the lower guard page
         * unbacked.
         *
         * Any valid stack address now has the PAGE_SHIFT bit as 1
         * and addresses corresponding to the guard page have the
         * PAGE_SHIFT bit as 0 - this is used for overflow detection.
         */
        ret = __create_hyp_mappings(base + PAGE_SIZE, PAGE_SIZE, phys_addr,
                                    PAGE_HYP);
        if (ret)
                kvm_err("Cannot map hyp stack\n");

        *haddr = base + size;

        return ret;
}

/**
 * create_hyp_io_mappings - Map IO into both kernel and HYP
 * @phys_addr:  The physical start address which gets mapped
 * @size:       Size of the region being mapped
 * @kaddr:      Kernel VA for this mapping
 * @haddr:      HYP VA for this mapping
 */
int create_hyp_io_mappings(phys_addr_t phys_addr, size_t size,
                           void __iomem **kaddr,
                           void __iomem **haddr)
{
        unsigned long addr;
        int ret;

        if (is_protected_kvm_enabled())
                return -EPERM;

        *kaddr = ioremap(phys_addr, size);
        if (!*kaddr)
                return -ENOMEM;

        if (is_kernel_in_hyp_mode()) {
                *haddr = *kaddr;
                return 0;
        }

        ret = __create_hyp_private_mapping(phys_addr, size,
                                           &addr, PAGE_HYP_DEVICE);
        if (ret) {
                iounmap(*kaddr);
                *kaddr = NULL;
                *haddr = NULL;
                return ret;
        }

        *haddr = (void __iomem *)addr;
        return 0;
}

/**
 * create_hyp_exec_mappings - Map an executable range into HYP
 * @phys_addr:  The physical start address which gets mapped
 * @size:       Size of the region being mapped
 * @haddr:      HYP VA for this mapping
 */
int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
                             void **haddr)
{
        unsigned long addr;
        int ret;

        BUG_ON(is_kernel_in_hyp_mode());

        ret = __create_hyp_private_mapping(phys_addr, size,
                                           &addr, PAGE_HYP_EXEC);
        if (ret) {
                *haddr = NULL;
                return ret;
        }

        *haddr = (void *)addr;
        return 0;
}

static struct kvm_pgtable_mm_ops kvm_user_mm_ops = {
        /* We shouldn't need any other callback to walk the PT */
        .phys_to_virt           = kvm_host_va,
};

static int get_user_mapping_size(struct kvm *kvm, u64 addr)
{
        struct kvm_pgtable pgt = {
                .pgd            = (kvm_pteref_t)kvm->mm->pgd,
                .ia_bits        = vabits_actual,
                .start_level    = (KVM_PGTABLE_LAST_LEVEL -
                                   CONFIG_PGTABLE_LEVELS + 1),
                .mm_ops         = &kvm_user_mm_ops,
        };
        unsigned long flags;
        kvm_pte_t pte = 0;      /* Keep GCC quiet... */
        s8 level = S8_MAX;
        int ret;

        /*
         * Disable IRQs so that we hazard against a concurrent
         * teardown of the userspace page tables (which relies on
         * IPI-ing threads).
         */
        local_irq_save(flags);
        ret = kvm_pgtable_get_leaf(&pgt, addr, &pte, &level);
        local_irq_restore(flags);

        if (ret)
                return ret;

        /*
         * Not seeing an error, but not updating level? Something went
         * deeply wrong...
         */
        if (WARN_ON(level > KVM_PGTABLE_LAST_LEVEL))
                return -EFAULT;
        if (WARN_ON(level < KVM_PGTABLE_FIRST_LEVEL))
                return -EFAULT;

        /* Oops, the userspace PTs are gone... Replay the fault */
        if (!kvm_pte_valid(pte))
                return -EAGAIN;

        return BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level));
}

static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
        .zalloc_page            = stage2_memcache_zalloc_page,
        .zalloc_pages_exact     = kvm_s2_zalloc_pages_exact,
        .free_pages_exact       = kvm_s2_free_pages_exact,
        .free_unlinked_table    = stage2_free_unlinked_table,
        .get_page               = kvm_host_get_page,
        .put_page               = kvm_s2_put_page,
        .page_count             = kvm_host_page_count,
        .phys_to_virt           = kvm_host_va,
        .virt_to_phys           = kvm_host_pa,
        .dcache_clean_inval_poc = clean_dcache_guest_page,
        .icache_inval_pou       = invalidate_icache_guest_page,
};

/**
 * kvm_init_stage2_mmu - Initialise a S2 MMU structure
 * @kvm:        The pointer to the KVM structure
 * @mmu:        The pointer to the s2 MMU structure
 * @type:       The machine type of the virtual machine
 *
 * Allocates only the stage-2 HW PGD level table(s).
 * Note we don't need locking here as this is only called when the VM is
 * created, which can only be done once.
 */
int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long type)
{
        u32 kvm_ipa_limit = get_kvm_ipa_limit();
        int cpu, err;
        struct kvm_pgtable *pgt;
        u64 mmfr0, mmfr1;
        u32 phys_shift;

        if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
                return -EINVAL;

        phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
        if (is_protected_kvm_enabled()) {
                phys_shift = kvm_ipa_limit;
        } else if (phys_shift) {
                if (phys_shift > kvm_ipa_limit ||
                    phys_shift < ARM64_MIN_PARANGE_BITS)
                        return -EINVAL;
        } else {
                phys_shift = KVM_PHYS_SHIFT;
                if (phys_shift > kvm_ipa_limit) {
                        pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
                                     current->comm);
                        return -EINVAL;
                }
        }

        mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
        mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
        mmu->vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);

        if (mmu->pgt != NULL) {
                kvm_err("kvm_arch already initialized?\n");
                return -EINVAL;
        }

        pgt = kzalloc(sizeof(*pgt), GFP_KERNEL_ACCOUNT);
        if (!pgt)
                return -ENOMEM;

        mmu->arch = &kvm->arch;
        err = kvm_pgtable_stage2_init(pgt, mmu, &kvm_s2_mm_ops);
        if (err)
                goto out_free_pgtable;

        mmu->last_vcpu_ran = alloc_percpu(typeof(*mmu->last_vcpu_ran));
        if (!mmu->last_vcpu_ran) {
                err = -ENOMEM;
                goto out_destroy_pgtable;
        }

        for_each_possible_cpu(cpu)
                *per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1;

         /* The eager page splitting is disabled by default */
        mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT;
        mmu->split_page_cache.gfp_zero = __GFP_ZERO;

        mmu->pgt = pgt;
        mmu->pgd_phys = __pa(pgt->pgd);
        return 0;

out_destroy_pgtable:
        kvm_pgtable_stage2_destroy(pgt);
out_free_pgtable:
        kfree(pgt);
        return err;
}

void kvm_uninit_stage2_mmu(struct kvm *kvm)
{
        kvm_free_stage2_pgd(&kvm->arch.mmu);
        kvm_mmu_free_memory_cache(&kvm->arch.mmu.split_page_cache);
}

static void stage2_unmap_memslot(struct kvm *kvm,
                                 struct kvm_memory_slot *memslot)
{
        hva_t hva = memslot->userspace_addr;
        phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
        phys_addr_t size = PAGE_SIZE * memslot->npages;
        hva_t reg_end = hva + size;

        /*
         * A memory region could potentially cover multiple VMAs, and any holes
         * between them, so iterate over all of them to find out if we should
         * unmap any of them.
         *
         *     +--------------------------------------------+
         * +---------------+----------------+   +----------------+
         * |   : VMA 1     |      VMA 2     |   |    VMA 3  :    |
         * +---------------+----------------+   +----------------+
         *     |               memory region                |
         *     +--------------------------------------------+
         */
        do {
                struct vm_area_struct *vma;
                hva_t vm_start, vm_end;

                vma = find_vma_intersection(current->mm, hva, reg_end);
                if (!vma)
                        break;

                /*
                 * Take the intersection of this VMA with the memory region
                 */
                vm_start = max(hva, vma->vm_start);
                vm_end = min(reg_end, vma->vm_end);

                if (!(vma->vm_flags & VM_PFNMAP)) {
                        gpa_t gpa = addr + (vm_start - memslot->userspace_addr);
                        unmap_stage2_range(&kvm->arch.mmu, gpa, vm_end - vm_start);
                }
                hva = vm_end;
        } while (hva < reg_end);
}

/**
 * stage2_unmap_vm - Unmap Stage-2 RAM mappings
 * @kvm: The struct kvm pointer
 *
 * Go through the memregions and unmap any regular RAM
 * backing memory already mapped to the VM.
 */
void stage2_unmap_vm(struct kvm *kvm)
{
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;
        int idx, bkt;

        idx = srcu_read_lock(&kvm->srcu);
        mmap_read_lock(current->mm);
        write_lock(&kvm->mmu_lock);

        slots = kvm_memslots(kvm);
        kvm_for_each_memslot(memslot, bkt, slots)
                stage2_unmap_memslot(kvm, memslot);

        write_unlock(&kvm->mmu_lock);
        mmap_read_unlock(current->mm);
        srcu_read_unlock(&kvm->srcu, idx);
}

void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
{
        struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
        struct kvm_pgtable *pgt = NULL;

        write_lock(&kvm->mmu_lock);
        pgt = mmu->pgt;
        if (pgt) {
                mmu->pgd_phys = 0;
                mmu->pgt = NULL;
                free_percpu(mmu->last_vcpu_ran);
        }
        write_unlock(&kvm->mmu_lock);

        if (pgt) {
                kvm_pgtable_stage2_destroy(pgt);
                kfree(pgt);
        }
}

static void hyp_mc_free_fn(void *addr, void *unused)
{
        free_page((unsigned long)addr);
}

static void *hyp_mc_alloc_fn(void *unused)
{
        return (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
}

void free_hyp_memcache(struct kvm_hyp_memcache *mc)
{
        if (is_protected_kvm_enabled())
                __free_hyp_memcache(mc, hyp_mc_free_fn,
                                    kvm_host_va, NULL);
}

int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages)
{
        if (!is_protected_kvm_enabled())
                return 0;

        return __topup_hyp_memcache(mc, min_pages, hyp_mc_alloc_fn,
                                    kvm_host_pa, NULL);
}

/**
 * kvm_phys_addr_ioremap - map a device range to guest IPA
 *
 * @kvm:        The KVM pointer
 * @guest_ipa:  The IPA at which to insert the mapping
 * @pa:         The physical address of the device
 * @size:       The size of the mapping
 * @writable:   Whether or not to create a writable mapping
 */
int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
                          phys_addr_t pa, unsigned long size, bool writable)
{
        phys_addr_t addr;
        int ret = 0;
        struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
        struct kvm_s2_mmu *mmu = &kvm->arch.mmu;
        struct kvm_pgtable *pgt = mmu->pgt;
        enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
                                     KVM_PGTABLE_PROT_R |
                                     (writable ? KVM_PGTABLE_PROT_W : 0);

        if (is_protected_kvm_enabled())
                return -EPERM;

        size += offset_in_page(guest_ipa);
        guest_ipa &= PAGE_MASK;

        for (addr = guest_ipa; addr < guest_ipa + size; addr += PAGE_SIZE) {
                ret = kvm_mmu_topup_memory_cache(&cache,
                                                 kvm_mmu_cache_min_pages(mmu));
                if (ret)
                        break;

                write_lock(&kvm->mmu_lock);
                ret = kvm_pgtable_stage2_map(pgt, addr, PAGE_SIZE, pa, prot,
                                             &cache, 0);
                write_unlock(&kvm->mmu_lock);
                if (ret)
                        break;

                pa += PAGE_SIZE;
        }

        kvm_mmu_free_memory_cache(&cache);
        return ret;
}

/**
 * stage2_wp_range() - write protect stage2 memory region range
 * @mmu:        The KVM stage-2 MMU pointer
 * @addr:       Start address of range
 * @end:        End address of range
 */
static void stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
{
        stage2_apply_range_resched(mmu, addr, end, kvm_pgtable_stage2_wrprotect);
}

/**
 * kvm_mmu_wp_memory_region() - write protect stage 2 entries for memory slot
 * @kvm:        The KVM pointer
 * @slot:       The memory slot to write protect
 *
 * Called to start logging dirty pages after memory region
 * KVM_MEM_LOG_DIRTY_PAGES operation is called. After this function returns
 * all present PUD, PMD and PTEs are write protected in the memory region.
 * Afterwards read of dirty page log can be called.
 *
 * Acquires kvm_mmu_lock. Called with kvm->slots_lock mutex acquired,
 * serializing operations for VM memory regions.
 */
static void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
{
        struct kvm_memslots *slots = kvm_memslots(kvm);
        struct kvm_memory_slot *memslot = id_to_memslot(slots, slot);
        phys_addr_t start, end;

        if (WARN_ON_ONCE(!memslot))
                return;

        start = memslot->base_gfn << PAGE_SHIFT;
        end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;

        write_lock(&kvm->mmu_lock);
        stage2_wp_range(&kvm->arch.mmu, start, end);
        write_unlock(&kvm->mmu_lock);
        kvm_flush_remote_tlbs_memslot(kvm, memslot);
}

/**
 * kvm_mmu_split_memory_region() - split the stage 2 blocks into PAGE_SIZE
 *                                 pages for memory slot
 * @kvm:        The KVM pointer
 * @slot:       The memory slot to split
 *
 * Acquires kvm->mmu_lock. Called with kvm->slots_lock mutex acquired,
 * serializing operations for VM memory regions.
 */
static void kvm_mmu_split_memory_region(struct kvm *kvm, int slot)
{
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;
        phys_addr_t start, end;

        lockdep_assert_held(&kvm->slots_lock);

        slots = kvm_memslots(kvm);
        memslot = id_to_memslot(slots, slot);

        start = memslot->base_gfn << PAGE_SHIFT;
        end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;

        write_lock(&kvm->mmu_lock);
        kvm_mmu_split_huge_pages(kvm, start, end);
        write_unlock(&kvm->mmu_lock);
}

/*
 * kvm_arch_mmu_enable_log_dirty_pt_masked() - enable dirty logging for selected pages.
 * @kvm:        The KVM pointer
 * @slot:       The memory slot associated with mask
 * @gfn_offset: The gfn offset in memory slot
 * @mask:       The mask of pages at offset 'gfn_offset' in this memory
 *              slot to enable dirty logging on
 *
 * Writes protect selected pages to enable dirty logging, and then
 * splits them to PAGE_SIZE. Caller must acquire kvm->mmu_lock.
 */
void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
                struct kvm_memory_slot *slot,
                gfn_t gfn_offset, unsigned long mask)
{
        phys_addr_t base_gfn = slot->base_gfn + gfn_offset;
        phys_addr_t start = (base_gfn +  __ffs(mask)) << PAGE_SHIFT;
        phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;

        lockdep_assert_held_write(&kvm->mmu_lock);

        stage2_wp_range(&kvm->arch.mmu, start, end);

        /*
         * Eager-splitting is done when manual-protect is set.  We
         * also check for initially-all-set because we can avoid
         * eager-splitting if initially-all-set is false.
         * Initially-all-set equal false implies that huge-pages were
         * already split when enabling dirty logging: no need to do it
         * again.
         */
        if (kvm_dirty_log_manual_protect_and_init_set(kvm))
                kvm_mmu_split_huge_pages(kvm, start, end);
}

static void kvm_send_hwpoison_signal(unsigned long address, short lsb)
{
        send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, current);
}

static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
                                               unsigned long hva,
                                               unsigned long map_size)
{
        gpa_t gpa_start;
        hva_t uaddr_start, uaddr_end;
        size_t size;

        /* The memslot and the VMA are guaranteed to be aligned to PAGE_SIZE */
        if (map_size == PAGE_SIZE)
                return true;

        size = memslot->npages * PAGE_SIZE;

        gpa_start = memslot->base_gfn << PAGE_SHIFT;

        uaddr_start = memslot->userspace_addr;
        uaddr_end = uaddr_start + size;

        /*
         * Pages belonging to memslots that don't have the same alignment
         * within a PMD/PUD for userspace and IPA cannot be mapped with stage-2
         * PMD/PUD entries, because we'll end up mapping the wrong pages.
         *
         * Consider a layout like the following:
         *
         *    memslot->userspace_addr:
         *    +-----+--------------------+--------------------+---+
         *    |abcde|fgh  Stage-1 block  |    Stage-1 block tv|xyz|
         *    +-----+--------------------+--------------------+---+
         *
         *    memslot->base_gfn << PAGE_SHIFT:
         *      +---+--------------------+--------------------+-----+
         *      |abc|def  Stage-2 block  |    Stage-2 block   |tvxyz|
         *      +---+--------------------+--------------------+-----+
         *
         * If we create those stage-2 blocks, we'll end up with this incorrect
         * mapping:
         *   d -> f
         *   e -> g
         *   f -> h
         */
        if ((gpa_start & (map_size - 1)) != (uaddr_start & (map_size - 1)))
                return false;

        /*
         * Next, let's make sure we're not trying to map anything not covered
         * by the memslot. This means we have to prohibit block size mappings
         * for the beginning and end of a non-block aligned and non-block sized
         * memory slot (illustrated by the head and tail parts of the
         * userspace view above containing pages 'abcde' and 'xyz',
         * respectively).
         *
         * Note that it doesn't matter if we do the check using the
         * userspace_addr or the base_gfn, as both are equally aligned (per
         * the check above) and equally sized.
         */
        return (hva & ~(map_size - 1)) >= uaddr_start &&
               (hva & ~(map_size - 1)) + map_size <= uaddr_end;
}

/*
 * Check if the given hva is backed by a transparent huge page (THP) and
 * whether it can be mapped using block mapping in stage2. If so, adjust
 * the stage2 PFN and IPA accordingly. Only PMD_SIZE THPs are currently
 * supported. This will need to be updated to support other THP sizes.
 *
 * Returns the size of the mapping.
 */
static long
transparent_hugepage_adjust(struct kvm *kvm, struct kvm_memory_slot *memslot,
                            unsigned long hva, kvm_pfn_t *pfnp,
                            phys_addr_t *ipap)
{
        kvm_pfn_t pfn = *pfnp;

        /*
         * Make sure the adjustment is done only for THP pages. Also make
         * sure that the HVA and IPA are sufficiently aligned and that the
         * block map is contained within the memslot.
         */
        if (fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE)) {
                int sz = get_user_mapping_size(kvm, hva);

                if (sz < 0)
                        return sz;

                if (sz < PMD_SIZE)
                        return PAGE_SIZE;

                *ipap &= PMD_MASK;
                pfn &= ~(PTRS_PER_PMD - 1);
                *pfnp = pfn;

                return PMD_SIZE;
        }

        /* Use page mapping if we cannot use block mapping. */
        return PAGE_SIZE;
}

static int get_vma_page_shift(struct vm_area_struct *vma, unsigned long hva)
{
        unsigned long pa;

        if (is_vm_hugetlb_page(vma) && !(vma->vm_flags & VM_PFNMAP))
                return huge_page_shift(hstate_vma(vma));

        if (!(vma->vm_flags & VM_PFNMAP))
                return PAGE_SHIFT;

        VM_BUG_ON(is_vm_hugetlb_page(vma));

        pa = (vma->vm_pgoff << PAGE_SHIFT) + (hva - vma->vm_start);

#ifndef __PAGETABLE_PMD_FOLDED
        if ((hva & (PUD_SIZE - 1)) == (pa & (PUD_SIZE - 1)) &&
            ALIGN_DOWN(hva, PUD_SIZE) >= vma->vm_start &&
            ALIGN(hva, PUD_SIZE) <= vma->vm_end)
                return PUD_SHIFT;
#endif

        if ((hva & (PMD_SIZE - 1)) == (pa & (PMD_SIZE - 1)) &&
            ALIGN_DOWN(hva, PMD_SIZE) >= vma->vm_start &&
            ALIGN(hva, PMD_SIZE) <= vma->vm_end)
                return PMD_SHIFT;

        return PAGE_SHIFT;
}

/*
 * The page will be mapped in stage 2 as Normal Cacheable, so the VM will be
 * able to see the page's tags and therefore they must be initialised first. If
 * PG_mte_tagged is set, tags have already been initialised.
 *
 * The race in the test/set of the PG_mte_tagged flag is handled by:
 * - preventing VM_SHARED mappings in a memslot with MTE preventing two VMs
 *   racing to santise the same page
 * - mmap_lock protects between a VM faulting a page in and the VMM performing
 *   an mprotect() to add VM_MTE
 */
static void sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,
                              unsigned long size)
{
        unsigned long i, nr_pages = size >> PAGE_SHIFT;
        struct page *page = pfn_to_page(pfn);

        if (!kvm_has_mte(kvm))
                return;

        for (i = 0; i < nr_pages; i++, page++) {
                if (try_page_mte_tagging(page)) {
                        mte_clear_page_tags(page_address(page));
                        set_page_mte_tagged(page);
                }
        }
}

static bool kvm_vma_mte_allowed(struct vm_area_struct *vma)
{
        return vma->vm_flags & VM_MTE_ALLOWED;
}

static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
                          struct kvm_memory_slot *memslot, unsigned long hva,
                          bool fault_is_perm)
{
        int ret = 0;
        bool write_fault, writable, force_pte = false;
        bool exec_fault, mte_allowed;
        bool device = false;
        unsigned long mmu_seq;
        struct kvm *kvm = vcpu->kvm;
        struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
        struct vm_area_struct *vma;
        short vma_shift;
        gfn_t gfn;
        kvm_pfn_t pfn;
        bool logging_active = memslot_is_logging(memslot);
        long vma_pagesize, fault_granule;
        enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
        struct kvm_pgtable *pgt;

        if (fault_is_perm)
                fault_granule = kvm_vcpu_trap_get_perm_fault_granule(vcpu);
        write_fault = kvm_is_write_fault(vcpu);
        exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu);
        VM_BUG_ON(write_fault && exec_fault);

        if (fault_is_perm && !write_fault && !exec_fault) {
                kvm_err("Unexpected L2 read permission error\n");
                return -EFAULT;
        }

        /*
         * Permission faults just need to update the existing leaf entry,
         * and so normally don't require allocations from the memcache. The
         * only exception to this is when dirty logging is enabled at runtime
         * and a write fault needs to collapse a block entry into a table.
         */
        if (!fault_is_perm || (logging_active && write_fault)) {
                ret = kvm_mmu_topup_memory_cache(memcache,
                                                 kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu));
                if (ret)
                        return ret;
        }

        /*
         * Let's check if we will get back a huge page backed by hugetlbfs, or
         * get block mapping for device MMIO region.
         */
        mmap_read_lock(current->mm);
        vma = vma_lookup(current->mm, hva);
        if (unlikely(!vma)) {
                kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
                mmap_read_unlock(current->mm);
                return -EFAULT;
        }

        /*
         * logging_active is guaranteed to never be true for VM_PFNMAP
         * memslots.
         */
        if (logging_active) {
                force_pte = true;
                vma_shift = PAGE_SHIFT;
        } else {
                vma_shift = get_vma_page_shift(vma, hva);
        }

        switch (vma_shift) {
#ifndef __PAGETABLE_PMD_FOLDED
        case PUD_SHIFT:
                if (fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
                        break;
                fallthrough;
#endif
        case CONT_PMD_SHIFT:
                vma_shift = PMD_SHIFT;
                fallthrough;
        case PMD_SHIFT:
                if (fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE))
                        break;
                fallthrough;
        case CONT_PTE_SHIFT:
                vma_shift = PAGE_SHIFT;
                force_pte = true;
                fallthrough;
        case PAGE_SHIFT:
                break;
        default:
                WARN_ONCE(1, "Unknown vma_shift %d", vma_shift);
        }

        vma_pagesize = 1UL << vma_shift;
        if (vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE)
                fault_ipa &= ~(vma_pagesize - 1);

        gfn = fault_ipa >> PAGE_SHIFT;
        mte_allowed = kvm_vma_mte_allowed(vma);

        /* Don't use the VMA after the unlock -- it may have vanished */
        vma = NULL;

        /*
         * Read mmu_invalidate_seq so that KVM can detect if the results of
         * vma_lookup() or __gfn_to_pfn_memslot() become stale prior to
         * acquiring kvm->mmu_lock.
         *
         * Rely on mmap_read_unlock() for an implicit smp_rmb(), which pairs
         * with the smp_wmb() in kvm_mmu_invalidate_end().
         */
        mmu_seq = vcpu->kvm->mmu_invalidate_seq;
        mmap_read_unlock(current->mm);

        pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL,
                                   write_fault, &writable, NULL);
        if (pfn == KVM_PFN_ERR_HWPOISON) {
                kvm_send_hwpoison_signal(hva, vma_shift);
                return 0;
        }
        if (is_error_noslot_pfn(pfn))
                return -EFAULT;

        if (kvm_is_device_pfn(pfn)) {
                /*
                 * If the page was identified as device early by looking at
                 * the VMA flags, vma_pagesize is already representing the
                 * largest quantity we can map.  If instead it was mapped
                 * via gfn_to_pfn_prot(), vma_pagesize is set to PAGE_SIZE
                 * and must not be upgraded.
                 *
                 * In both cases, we don't let transparent_hugepage_adjust()
                 * change things at the last minute.
                 */
                device = true;
        } else if (logging_active && !write_fault) {
                /*
                 * Only actually map the page as writable if this was a write
                 * fault.
                 */
                writable = false;
        }

        if (exec_fault && device)
                return -ENOEXEC;

        read_lock(&kvm->mmu_lock);
        pgt = vcpu->arch.hw_mmu->pgt;
        if (mmu_invalidate_retry(kvm, mmu_seq))
                goto out_unlock;

        /*
         * If we are not forced to use page mapping, check if we are
         * backed by a THP and thus use block mapping if possible.
         */
        if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) {
                if (fault_is_perm && fault_granule > PAGE_SIZE)
                        vma_pagesize = fault_granule;
                else
                        vma_pagesize = transparent_hugepage_adjust(kvm, memslot,
                                                                   hva, &pfn,
                                                                   &fault_ipa);

                if (vma_pagesize < 0) {
                        ret = vma_pagesize;
                        goto out_unlock;
                }
        }

        if (!fault_is_perm && !device && kvm_has_mte(kvm)) {
                /* Check the VMM hasn't introduced a new disallowed VMA */
                if (mte_allowed) {
                        sanitise_mte_tags(kvm, pfn, vma_pagesize);
                } else {
                        ret = -EFAULT;
                        goto out_unlock;
                }
        }

        if (writable)
                prot |= KVM_PGTABLE_PROT_W;

        if (exec_fault)
                prot |= KVM_PGTABLE_PROT_X;

        if (device)
                prot |= KVM_PGTABLE_PROT_DEVICE;
        else if (cpus_have_final_cap(ARM64_HAS_CACHE_DIC))
                prot |= KVM_PGTABLE_PROT_X;

        /*
         * Under the premise of getting a FSC_PERM fault, we just need to relax
         * permissions only if vma_pagesize equals fault_granule. Otherwise,
         * kvm_pgtable_stage2_map() should be called to change block size.
         */
        if (fault_is_perm && vma_pagesize == fault_granule)
                ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot);
        else
                ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize,
                                             __pfn_to_phys(pfn), prot,
                                             memcache,
                                             KVM_PGTABLE_WALK_HANDLE_FAULT |
                                             KVM_PGTABLE_WALK_SHARED);

        /* Mark the page dirty only if the fault is handled successfully */
        if (writable && !ret) {
                kvm_set_pfn_dirty(pfn);
                mark_page_dirty_in_slot(kvm, memslot, gfn);
        }

out_unlock:
        read_unlock(&kvm->mmu_lock);
        kvm_release_pfn_clean(pfn);
        return ret != -EAGAIN ? ret : 0;
}

/* Resolve the access fault by making the page young again. */
static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
{
        kvm_pte_t pte;
        struct kvm_s2_mmu *mmu;

        trace_kvm_access_fault(fault_ipa);

        read_lock(&vcpu->kvm->mmu_lock);
        mmu = vcpu->arch.hw_mmu;
        pte = kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa);
        read_unlock(&vcpu->kvm->mmu_lock);

        if (kvm_pte_valid(pte))
                kvm_set_pfn_accessed(kvm_pte_to_pfn(pte));
}

/**
 * kvm_handle_guest_abort - handles all 2nd stage aborts
 * @vcpu:       the VCPU pointer
 *
 * Any abort that gets to the host is almost guaranteed to be caused by a
 * missing second stage translation table entry, which can mean that either the
 * guest simply needs more memory and we must allocate an appropriate page or it
 * can mean that the guest tried to access I/O memory, which is emulated by user
 * space. The distinction is based on the IPA causing the fault and whether this
 * memory region has been registered as standard RAM by user space.
 */
int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
{
        unsigned long esr;
        phys_addr_t fault_ipa;
        struct kvm_memory_slot *memslot;
        unsigned long hva;
        bool is_iabt, write_fault, writable;
        gfn_t gfn;
        int ret, idx;

        esr = kvm_vcpu_get_esr(vcpu);

        fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
        is_iabt = kvm_vcpu_trap_is_iabt(vcpu);

        if (esr_fsc_is_translation_fault(esr)) {
                /* Beyond sanitised PARange (which is the IPA limit) */
                if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) {
                        kvm_inject_size_fault(vcpu);
                        return 1;
                }

                /* Falls between the IPA range and the PARange? */
                if (fault_ipa >= BIT_ULL(vcpu->arch.hw_mmu->pgt->ia_bits)) {
                        fault_ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);

                        if (is_iabt)
                                kvm_inject_pabt(vcpu, fault_ipa);
                        else
                                kvm_inject_dabt(vcpu, fault_ipa);
                        return 1;
                }
        }

        /* Synchronous External Abort? */
        if (kvm_vcpu_abt_issea(vcpu)) {
                /*
                 * For RAS the host kernel may handle this abort.
                 * There is no need to pass the error into the guest.
                 */
                if (kvm_handle_guest_sea(fault_ipa, kvm_vcpu_get_esr(vcpu)))
                        kvm_inject_vabt(vcpu);

                return 1;
        }

        trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),
                              kvm_vcpu_get_hfar(vcpu), fault_ipa);

        /* Check the stage-2 fault is trans. fault or write fault */
        if (!esr_fsc_is_translation_fault(esr) &&
            !esr_fsc_is_permission_fault(esr) &&
            !esr_fsc_is_access_flag_fault(esr)) {
                kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n",
                        kvm_vcpu_trap_get_class(vcpu),
                        (unsigned long)kvm_vcpu_trap_get_fault(vcpu),
                        (unsigned long)kvm_vcpu_get_esr(vcpu));
                return -EFAULT;
        }

        idx = srcu_read_lock(&vcpu->kvm->srcu);

        gfn = fault_ipa >> PAGE_SHIFT;
        memslot = gfn_to_memslot(vcpu->kvm, gfn);
        hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
        write_fault = kvm_is_write_fault(vcpu);
        if (kvm_is_error_hva(hva) || (write_fault && !writable)) {
                /*
                 * The guest has put either its instructions or its page-tables
                 * somewhere it shouldn't have. Userspace won't be able to do
                 * anything about this (there's no syndrome for a start), so
                 * re-inject the abort back into the guest.
                 */
                if (is_iabt) {
                        ret = -ENOEXEC;
                        goto out;
                }

                if (kvm_vcpu_abt_iss1tw(vcpu)) {
                        kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
                        ret = 1;
                        goto out_unlock;
                }

                /*
                 * Check for a cache maintenance operation. Since we
                 * ended-up here, we know it is outside of any memory
                 * slot. But we can't find out if that is for a device,
                 * or if the guest is just being stupid. The only thing
                 * we know for sure is that this range cannot be cached.
                 *
                 * So let's assume that the guest is just being
                 * cautious, and skip the instruction.
                 */
                if (kvm_is_error_hva(hva) && kvm_vcpu_dabt_is_cm(vcpu)) {
                        kvm_incr_pc(vcpu);
                        ret = 1;
                        goto out_unlock;
                }

                /*
                 * The IPA is reported as [MAX:12], so we need to
                 * complement it with the bottom 12 bits from the
                 * faulting VA. This is always 12 bits, irrespective
                 * of the page size.
                 */
                fault_ipa |= kvm_vcpu_get_hfar(vcpu) & ((1 << 12) - 1);
                ret = io_mem_abort(vcpu, fault_ipa);
                goto out_unlock;
        }

        /* Userspace should not be able to register out-of-bounds IPAs */
        VM_BUG_ON(fault_ipa >= kvm_phys_size(vcpu->arch.hw_mmu));

        if (esr_fsc_is_access_flag_fault(esr)) {
                handle_access_fault(vcpu, fault_ipa);
                ret = 1;
                goto out_unlock;
        }

        ret = user_mem_abort(vcpu, fault_ipa, memslot, hva,
                             esr_fsc_is_permission_fault(esr));
        if (ret == 0)
                ret = 1;
out:
        if (ret == -ENOEXEC) {
                kvm_inject_pabt(vcpu, kvm_vcpu_get_hfar(vcpu));
                ret = 1;
        }
out_unlock:
        srcu_read_unlock(&vcpu->kvm->srcu, idx);
        return ret;
}

bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
{
        if (!kvm->arch.mmu.pgt)
                return false;

        __unmap_stage2_range(&kvm->arch.mmu, range->start << PAGE_SHIFT,
                             (range->end - range->start) << PAGE_SHIFT,
                             range->may_block);

        return false;
}

bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
        kvm_pfn_t pfn = pte_pfn(range->arg.pte);

        if (!kvm->arch.mmu.pgt)
                return false;

        WARN_ON(range->end - range->start != 1);

        /*
         * If the page isn't tagged, defer to user_mem_abort() for sanitising
         * the MTE tags. The S2 pte should have been unmapped by
         * mmu_notifier_invalidate_range_end().
         */
        if (kvm_has_mte(kvm) && !page_mte_tagged(pfn_to_page(pfn)))
                return false;

        /*
         * We've moved a page around, probably through CoW, so let's treat
         * it just like a translation fault and the map handler will clean
         * the cache to the PoC.
         *
         * The MMU notifiers will have unmapped a huge PMD before calling
         * ->change_pte() (which in turn calls kvm_set_spte_gfn()) and
         * therefore we never need to clear out a huge PMD through this
         * calling path and a memcache is not required.
         */
        kvm_pgtable_stage2_map(kvm->arch.mmu.pgt, range->start << PAGE_SHIFT,
                               PAGE_SIZE, __pfn_to_phys(pfn),
                               KVM_PGTABLE_PROT_R, NULL, 0);

        return false;
}

bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
        u64 size = (range->end - range->start) << PAGE_SHIFT;

        if (!kvm->arch.mmu.pgt)
                return false;

        return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt,
                                                   range->start << PAGE_SHIFT,
                                                   size, true);
}

bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
        u64 size = (range->end - range->start) << PAGE_SHIFT;

        if (!kvm->arch.mmu.pgt)
                return false;

        return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt,
                                                   range->start << PAGE_SHIFT,
                                                   size, false);
}

phys_addr_t kvm_mmu_get_httbr(void)
{
        return __pa(hyp_pgtable->pgd);
}

phys_addr_t kvm_get_idmap_vector(void)
{
        return hyp_idmap_vector;
}

static int kvm_map_idmap_text(void)
{
        unsigned long size = hyp_idmap_end - hyp_idmap_start;
        int err = __create_hyp_mappings(hyp_idmap_start, size, hyp_idmap_start,
                                        PAGE_HYP_EXEC);
        if (err)
                kvm_err("Failed to idmap %lx-%lx\n",
                        hyp_idmap_start, hyp_idmap_end);

        return err;
}

static void *kvm_hyp_zalloc_page(void *arg)
{
        return (void *)get_zeroed_page(GFP_KERNEL);
}

static struct kvm_pgtable_mm_ops kvm_hyp_mm_ops = {
        .zalloc_page            = kvm_hyp_zalloc_page,
        .get_page               = kvm_host_get_page,
        .put_page               = kvm_host_put_page,
        .phys_to_virt           = kvm_host_va,
        .virt_to_phys           = kvm_host_pa,
};

int __init kvm_mmu_init(u32 *hyp_va_bits)
{
        int err;
        u32 idmap_bits;
        u32 kernel_bits;

        hyp_idmap_start = __pa_symbol(__hyp_idmap_text_start);
        hyp_idmap_start = ALIGN_DOWN(hyp_idmap_start, PAGE_SIZE);
        hyp_idmap_end = __pa_symbol(__hyp_idmap_text_end);
        hyp_idmap_end = ALIGN(hyp_idmap_end, PAGE_SIZE);
        hyp_idmap_vector = __pa_symbol(__kvm_hyp_init);

        /*
         * We rely on the linker script to ensure at build time that the HYP
         * init code does not cross a page boundary.
         */
        BUG_ON((hyp_idmap_start ^ (hyp_idmap_end - 1)) & PAGE_MASK);

        /*
         * The ID map may be configured to use an extended virtual address
         * range. This is only the case if system RAM is out of range for the
         * currently configured page size and VA_BITS_MIN, in which case we will
         * also need the extended virtual range for the HYP ID map, or we won't
         * be able to enable the EL2 MMU.
         *
         * However, in some cases the ID map may be configured for fewer than
         * the number of VA bits used by the regular kernel stage 1. This
         * happens when VA_BITS=52 and the kernel image is placed in PA space
         * below 48 bits.
         *
         * At EL2, there is only one TTBR register, and we can't switch between
         * translation tables *and* update TCR_EL2.T0SZ at the same time. Bottom
         * line: we need to use the extended range with *both* our translation
         * tables.
         *
         * So use the maximum of the idmap VA bits and the regular kernel stage
         * 1 VA bits to assure that the hypervisor can both ID map its code page
         * and map any kernel memory.
         */
        idmap_bits = 64 - ((idmap_t0sz & TCR_T0SZ_MASK) >> TCR_T0SZ_OFFSET);
        kernel_bits = vabits_actual;
        *hyp_va_bits = max(idmap_bits, kernel_bits);

        kvm_debug("Using %u-bit virtual addresses at EL2\n", *hyp_va_bits);
        kvm_debug("IDMAP page: %lx\n", hyp_idmap_start);
        kvm_debug("HYP VA range: %lx:%lx\n",
                  kern_hyp_va(PAGE_OFFSET),
                  kern_hyp_va((unsigned long)high_memory - 1));

        if (hyp_idmap_start >= kern_hyp_va(PAGE_OFFSET) &&
            hyp_idmap_start <  kern_hyp_va((unsigned long)high_memory - 1) &&
            hyp_idmap_start != (unsigned long)__hyp_idmap_text_start) {
                /*
                 * The idmap page is intersecting with the VA space,
                 * it is not safe to continue further.
                 */
                kvm_err("IDMAP intersecting with HYP VA, unable to continue\n");
                err = -EINVAL;
                goto out;
        }

        hyp_pgtable = kzalloc(sizeof(*hyp_pgtable), GFP_KERNEL);
        if (!hyp_pgtable) {
                kvm_err("Hyp mode page-table not allocated\n");
                err = -ENOMEM;
                goto out;
        }

        err = kvm_pgtable_hyp_init(hyp_pgtable, *hyp_va_bits, &kvm_hyp_mm_ops);
        if (err)
                goto out_free_pgtable;

        err = kvm_map_idmap_text();
        if (err)
                goto out_destroy_pgtable;

        io_map_base = hyp_idmap_start;
        return 0;

out_destroy_pgtable:
        kvm_pgtable_hyp_destroy(hyp_pgtable);
out_free_pgtable:
        kfree(hyp_pgtable);
        hyp_pgtable = NULL;
out:
        return err;
}

void kvm_arch_commit_memory_region(struct kvm *kvm,
                                   struct kvm_memory_slot *old,
                                   const struct kvm_memory_slot *new,
                                   enum kvm_mr_change change)
{
        bool log_dirty_pages = new && new->flags & KVM_MEM_LOG_DIRTY_PAGES;

        /*
         * At this point memslot has been committed and there is an
         * allocated dirty_bitmap[], dirty pages will be tracked while the
         * memory slot is write protected.
         */
        if (log_dirty_pages) {

                if (change == KVM_MR_DELETE)
                        return;

                /*
                 * Huge and normal pages are write-protected and split
                 * on either of these two cases:
                 *
                 * 1. with initial-all-set: gradually with CLEAR ioctls,
                 */
                if (kvm_dirty_log_manual_protect_and_init_set(kvm))
                        return;
                /*
                 * or
                 * 2. without initial-all-set: all in one shot when
                 *    enabling dirty logging.
                 */
                kvm_mmu_wp_memory_region(kvm, new->id);
                kvm_mmu_split_memory_region(kvm, new->id);
        } else {
                /*
                 * Free any leftovers from the eager page splitting cache. Do
                 * this when deleting, moving, disabling dirty logging, or
                 * creating the memslot (a nop). Doing it for deletes makes
                 * sure we don't leak memory, and there's no need to keep the
                 * cache around for any of the other cases.
                 */
                kvm_mmu_free_memory_cache(&kvm->arch.mmu.split_page_cache);
        }
}

int kvm_arch_prepare_memory_region(struct kvm *kvm,
                                   const struct kvm_memory_slot *old,
                                   struct kvm_memory_slot *new,
                                   enum kvm_mr_change change)
{
        hva_t hva, reg_end;
        int ret = 0;

        if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&
                        change != KVM_MR_FLAGS_ONLY)
                return 0;

        /*
         * Prevent userspace from creating a memory region outside of the IPA
         * space addressable by the KVM guest IPA space.
         */
        if ((new->base_gfn + new->npages) > (kvm_phys_size(&kvm->arch.mmu) >> PAGE_SHIFT))
                return -EFAULT;

        hva = new->userspace_addr;
        reg_end = hva + (new->npages << PAGE_SHIFT);

        mmap_read_lock(current->mm);
        /*
         * A memory region could potentially cover multiple VMAs, and any holes
         * between them, so iterate over all of them.
         *
         *     +--------------------------------------------+
         * +---------------+----------------+   +----------------+
         * |   : VMA 1     |      VMA 2     |   |    VMA 3  :    |
         * +---------------+----------------+   +----------------+
         *     |               memory region                |
         *     +--------------------------------------------+
         */
        do {
                struct vm_area_struct *vma;

                vma = find_vma_intersection(current->mm, hva, reg_end);
                if (!vma)
                        break;

                if (kvm_has_mte(kvm) && !kvm_vma_mte_allowed(vma)) {
                        ret = -EINVAL;
                        break;
                }

                if (vma->vm_flags & VM_PFNMAP) {
                        /* IO region dirty page logging not allowed */
                        if (new->flags & KVM_MEM_LOG_DIRTY_PAGES) {
                                ret = -EINVAL;
                                break;
                        }
                }
                hva = min(reg_end, vma->vm_end);
        } while (hva < reg_end);

        mmap_read_unlock(current->mm);
        return ret;
}

void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
{
}

void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
{
}

void kvm_arch_flush_shadow_all(struct kvm *kvm)
{
        kvm_uninit_stage2_mmu(kvm);
}

void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
                                   struct kvm_memory_slot *slot)
{
        gpa_t gpa = slot->base_gfn << PAGE_SHIFT;
        phys_addr_t size = slot->npages << PAGE_SHIFT;

        write_lock(&kvm->mmu_lock);
        unmap_stage2_range(&kvm->arch.mmu, gpa, size);
        write_unlock(&kvm->mmu_lock);
}

/*
 * See note at ARMv7 ARM B1.14.4 (TL;DR: S/W ops are not easily virtualized).
 *
 * Main problems:
 * - S/W ops are local to a CPU (not broadcast)
 * - We have line migration behind our back (speculation)
 * - System caches don't support S/W at all (damn!)
 *
 * In the face of the above, the best we can do is to try and convert
 * S/W ops to VA ops. Because the guest is not allowed to infer the
 * S/W to PA mapping, it can only use S/W to nuke the whole cache,
 * which is a rather good thing for us.
 *
 * Also, it is only used when turning caches on/off ("The expected
 * usage of the cache maintenance instructions that operate by set/way
 * is associated with the cache maintenance instructions associated
 * with the powerdown and powerup of caches, if this is required by
 * the implementation.").
 *
 * We use the following policy:
 *
 * - If we trap a S/W operation, we enable VM trapping to detect
 *   caches being turned on/off, and do a full clean.
 *
 * - We flush the caches on both caches being turned on and off.
 *
 * - Once the caches are enabled, we stop trapping VM ops.
 */
void kvm_set_way_flush(struct kvm_vcpu *vcpu)
{
        unsigned long hcr = *vcpu_hcr(vcpu);

        /*
         * If this is the first time we do a S/W operation
         * (i.e. HCR_TVM not set) flush the whole memory, and set the
         * VM trapping.
         *
         * Otherwise, rely on the VM trapping to wait for the MMU +
         * Caches to be turned off. At that point, we'll be able to
         * clean the caches again.
         */
        if (!(hcr & HCR_TVM)) {
                trace_kvm_set_way_flush(*vcpu_pc(vcpu),
                                        vcpu_has_cache_enabled(vcpu));
                stage2_flush_vm(vcpu->kvm);
                *vcpu_hcr(vcpu) = hcr | HCR_TVM;
        }
}

void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled)
{
        bool now_enabled = vcpu_has_cache_enabled(vcpu);

        /*
         * If switching the MMU+caches on, need to invalidate the caches.
         * If switching it off, need to clean the caches.
         * Clean + invalidate does the trick always.
         */
        if (now_enabled != was_enabled)
                stage2_flush_vm(vcpu->kvm);

        /* Caches are now on, stop trapping VM ops (until a S/W op) */
        if (now_enabled)
                *vcpu_hcr(vcpu) &= ~HCR_TVM;

        trace_kvm_toggle_cache(*vcpu_pc(vcpu), was_enabled, now_enabled);
}