fs: common implementation of file type

[linux.git] / virt / kvm / arm / mmu.c

/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#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_mmio.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/virt.h>
#include <asm/system_misc.h>

#include "trace.h"

static pgd_t *boot_hyp_pgd;
static pgd_t *hyp_pgd;
static pgd_t *merged_hyp_pgd;
static DEFINE_MUTEX(kvm_hyp_pgd_mutex);

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

static unsigned long io_map_base;

#define hyp_pgd_order get_order(PTRS_PER_PGD * sizeof(pgd_t))

#define KVM_S2PTE_FLAG_IS_IOMAP         (1UL << 0)
#define KVM_S2_FLAG_LOGGING_ACTIVE      (1UL << 1)

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

/**
 * kvm_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
 */
void kvm_flush_remote_tlbs(struct kvm *kvm)
{
        kvm_call_hyp(__kvm_tlb_flush_vmid, kvm);
}

static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
{
        kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, kvm, ipa);
}

/*
 * D-Cache management functions. They take the page table entries by
 * value, as they are flushing the cache using the kernel mapping (or
 * kmap on 32bit).
 */
static void kvm_flush_dcache_pte(pte_t pte)
{
        __kvm_flush_dcache_pte(pte);
}

static void kvm_flush_dcache_pmd(pmd_t pmd)
{
        __kvm_flush_dcache_pmd(pmd);
}

static void kvm_flush_dcache_pud(pud_t pud)
{
        __kvm_flush_dcache_pud(pud);
}

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

/**
 * stage2_dissolve_pmd() - clear and flush huge PMD entry
 * @kvm:        pointer to kvm structure.
 * @addr:       IPA
 * @pmd:        pmd pointer for IPA
 *
 * Function clears a PMD entry, flushes addr 1st and 2nd stage TLBs. Marks all
 * pages in the range dirty.
 */
static void stage2_dissolve_pmd(struct kvm *kvm, phys_addr_t addr, pmd_t *pmd)
{
        if (!pmd_thp_or_huge(*pmd))
                return;

        pmd_clear(pmd);
        kvm_tlb_flush_vmid_ipa(kvm, addr);
        put_page(virt_to_page(pmd));
}

/**
 * stage2_dissolve_pud() - clear and flush huge PUD entry
 * @kvm:        pointer to kvm structure.
 * @addr:       IPA
 * @pud:        pud pointer for IPA
 *
 * Function clears a PUD entry, flushes addr 1st and 2nd stage TLBs. Marks all
 * pages in the range dirty.
 */
static void stage2_dissolve_pud(struct kvm *kvm, phys_addr_t addr, pud_t *pudp)
{
        if (!stage2_pud_huge(kvm, *pudp))
                return;

        stage2_pud_clear(kvm, pudp);
        kvm_tlb_flush_vmid_ipa(kvm, addr);
        put_page(virt_to_page(pudp));
}

static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
                                  int min, int max)
{
        void *page;

        BUG_ON(max > KVM_NR_MEM_OBJS);
        if (cache->nobjs >= min)
                return 0;
        while (cache->nobjs < max) {
                page = (void *)__get_free_page(PGALLOC_GFP);
                if (!page)
                        return -ENOMEM;
                cache->objects[cache->nobjs++] = page;
        }
        return 0;
}

static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
{
        while (mc->nobjs)
                free_page((unsigned long)mc->objects[--mc->nobjs]);
}

static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
{
        void *p;

        BUG_ON(!mc || !mc->nobjs);
        p = mc->objects[--mc->nobjs];
        return p;
}

static void clear_stage2_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
{
        pud_t *pud_table __maybe_unused = stage2_pud_offset(kvm, pgd, 0UL);
        stage2_pgd_clear(kvm, pgd);
        kvm_tlb_flush_vmid_ipa(kvm, addr);
        stage2_pud_free(kvm, pud_table);
        put_page(virt_to_page(pgd));
}

static void clear_stage2_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
{
        pmd_t *pmd_table __maybe_unused = stage2_pmd_offset(kvm, pud, 0);
        VM_BUG_ON(stage2_pud_huge(kvm, *pud));
        stage2_pud_clear(kvm, pud);
        kvm_tlb_flush_vmid_ipa(kvm, addr);
        stage2_pmd_free(kvm, pmd_table);
        put_page(virt_to_page(pud));
}

static void clear_stage2_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
{
        pte_t *pte_table = pte_offset_kernel(pmd, 0);
        VM_BUG_ON(pmd_thp_or_huge(*pmd));
        pmd_clear(pmd);
        kvm_tlb_flush_vmid_ipa(kvm, addr);
        pte_free_kernel(NULL, pte_table);
        put_page(virt_to_page(pmd));
}

static inline void kvm_set_pte(pte_t *ptep, pte_t new_pte)
{
        WRITE_ONCE(*ptep, new_pte);
        dsb(ishst);
}

static inline void kvm_set_pmd(pmd_t *pmdp, pmd_t new_pmd)
{
        WRITE_ONCE(*pmdp, new_pmd);
        dsb(ishst);
}

static inline void kvm_pmd_populate(pmd_t *pmdp, pte_t *ptep)
{
        kvm_set_pmd(pmdp, kvm_mk_pmd(ptep));
}

static inline void kvm_pud_populate(pud_t *pudp, pmd_t *pmdp)
{
        WRITE_ONCE(*pudp, kvm_mk_pud(pmdp));
        dsb(ishst);
}

static inline void kvm_pgd_populate(pgd_t *pgdp, pud_t *pudp)
{
        WRITE_ONCE(*pgdp, kvm_mk_pgd(pudp));
        dsb(ishst);
}

/*
 * 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 call kvm_flush_dcache_p*() 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.
 */
static void unmap_stage2_ptes(struct kvm *kvm, pmd_t *pmd,
                       phys_addr_t addr, phys_addr_t end)
{
        phys_addr_t start_addr = addr;
        pte_t *pte, *start_pte;

        start_pte = pte = pte_offset_kernel(pmd, addr);
        do {
                if (!pte_none(*pte)) {
                        pte_t old_pte = *pte;

                        kvm_set_pte(pte, __pte(0));
                        kvm_tlb_flush_vmid_ipa(kvm, addr);

                        /* No need to invalidate the cache for device mappings */
                        if (!kvm_is_device_pfn(pte_pfn(old_pte)))
                                kvm_flush_dcache_pte(old_pte);

                        put_page(virt_to_page(pte));
                }
        } while (pte++, addr += PAGE_SIZE, addr != end);

        if (stage2_pte_table_empty(kvm, start_pte))
                clear_stage2_pmd_entry(kvm, pmd, start_addr);
}

static void unmap_stage2_pmds(struct kvm *kvm, pud_t *pud,
                       phys_addr_t addr, phys_addr_t end)
{
        phys_addr_t next, start_addr = addr;
        pmd_t *pmd, *start_pmd;

        start_pmd = pmd = stage2_pmd_offset(kvm, pud, addr);
        do {
                next = stage2_pmd_addr_end(kvm, addr, end);
                if (!pmd_none(*pmd)) {
                        if (pmd_thp_or_huge(*pmd)) {
                                pmd_t old_pmd = *pmd;

                                pmd_clear(pmd);
                                kvm_tlb_flush_vmid_ipa(kvm, addr);

                                kvm_flush_dcache_pmd(old_pmd);

                                put_page(virt_to_page(pmd));
                        } else {
                                unmap_stage2_ptes(kvm, pmd, addr, next);
                        }
                }
        } while (pmd++, addr = next, addr != end);

        if (stage2_pmd_table_empty(kvm, start_pmd))
                clear_stage2_pud_entry(kvm, pud, start_addr);
}

static void unmap_stage2_puds(struct kvm *kvm, pgd_t *pgd,
                       phys_addr_t addr, phys_addr_t end)
{
        phys_addr_t next, start_addr = addr;
        pud_t *pud, *start_pud;

        start_pud = pud = stage2_pud_offset(kvm, pgd, addr);
        do {
                next = stage2_pud_addr_end(kvm, addr, end);
                if (!stage2_pud_none(kvm, *pud)) {
                        if (stage2_pud_huge(kvm, *pud)) {
                                pud_t old_pud = *pud;

                                stage2_pud_clear(kvm, pud);
                                kvm_tlb_flush_vmid_ipa(kvm, addr);
                                kvm_flush_dcache_pud(old_pud);
                                put_page(virt_to_page(pud));
                        } else {
                                unmap_stage2_pmds(kvm, pud, addr, next);
                        }
                }
        } while (pud++, addr = next, addr != end);

        if (stage2_pud_table_empty(kvm, start_pud))
                clear_stage2_pgd_entry(kvm, pgd, start_addr);
}

/**
 * unmap_stage2_range -- Clear stage2 page table entries to unmap a range
 * @kvm:   The VM pointer
 * @start: The intermediate physical base address of the range to unmap
 * @size:  The size of the area to unmap
 *
 * 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 *kvm, phys_addr_t start, u64 size)
{
        pgd_t *pgd;
        phys_addr_t addr = start, end = start + size;
        phys_addr_t next;

        assert_spin_locked(&kvm->mmu_lock);
        WARN_ON(size & ~PAGE_MASK);

        pgd = kvm->arch.pgd + stage2_pgd_index(kvm, addr);
        do {
                /*
                 * Make sure the page table is still active, as another thread
                 * could have possibly freed the page table, while we released
                 * the lock.
                 */
                if (!READ_ONCE(kvm->arch.pgd))
                        break;
                next = stage2_pgd_addr_end(kvm, addr, end);
                if (!stage2_pgd_none(kvm, *pgd))
                        unmap_stage2_puds(kvm, pgd, addr, next);
                /*
                 * If the range is too large, release the kvm->mmu_lock
                 * to prevent starvation and lockup detector warnings.
                 */
                if (next != end)
                        cond_resched_lock(&kvm->mmu_lock);
        } while (pgd++, addr = next, addr != end);
}

static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
                              phys_addr_t addr, phys_addr_t end)
{
        pte_t *pte;

        pte = pte_offset_kernel(pmd, addr);
        do {
                if (!pte_none(*pte) && !kvm_is_device_pfn(pte_pfn(*pte)))
                        kvm_flush_dcache_pte(*pte);
        } while (pte++, addr += PAGE_SIZE, addr != end);
}

static void stage2_flush_pmds(struct kvm *kvm, pud_t *pud,
                              phys_addr_t addr, phys_addr_t end)
{
        pmd_t *pmd;
        phys_addr_t next;

        pmd = stage2_pmd_offset(kvm, pud, addr);
        do {
                next = stage2_pmd_addr_end(kvm, addr, end);
                if (!pmd_none(*pmd)) {
                        if (pmd_thp_or_huge(*pmd))
                                kvm_flush_dcache_pmd(*pmd);
                        else
                                stage2_flush_ptes(kvm, pmd, addr, next);
                }
        } while (pmd++, addr = next, addr != end);
}

static void stage2_flush_puds(struct kvm *kvm, pgd_t *pgd,
                              phys_addr_t addr, phys_addr_t end)
{
        pud_t *pud;
        phys_addr_t next;

        pud = stage2_pud_offset(kvm, pgd, addr);
        do {
                next = stage2_pud_addr_end(kvm, addr, end);
                if (!stage2_pud_none(kvm, *pud)) {
                        if (stage2_pud_huge(kvm, *pud))
                                kvm_flush_dcache_pud(*pud);
                        else
                                stage2_flush_pmds(kvm, pud, addr, next);
                }
        } while (pud++, addr = next, addr != end);
}

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;
        phys_addr_t next;
        pgd_t *pgd;

        pgd = kvm->arch.pgd + stage2_pgd_index(kvm, addr);
        do {
                next = stage2_pgd_addr_end(kvm, addr, end);
                if (!stage2_pgd_none(kvm, *pgd))
                        stage2_flush_puds(kvm, pgd, addr, next);
        } while (pgd++, addr = next, addr != end);
}

/**
 * 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;

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

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

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

static void clear_hyp_pgd_entry(pgd_t *pgd)
{
        pud_t *pud_table __maybe_unused = pud_offset(pgd, 0UL);
        pgd_clear(pgd);
        pud_free(NULL, pud_table);
        put_page(virt_to_page(pgd));
}

static void clear_hyp_pud_entry(pud_t *pud)
{
        pmd_t *pmd_table __maybe_unused = pmd_offset(pud, 0);
        VM_BUG_ON(pud_huge(*pud));
        pud_clear(pud);
        pmd_free(NULL, pmd_table);
        put_page(virt_to_page(pud));
}

static void clear_hyp_pmd_entry(pmd_t *pmd)
{
        pte_t *pte_table = pte_offset_kernel(pmd, 0);
        VM_BUG_ON(pmd_thp_or_huge(*pmd));
        pmd_clear(pmd);
        pte_free_kernel(NULL, pte_table);
        put_page(virt_to_page(pmd));
}

static void unmap_hyp_ptes(pmd_t *pmd, phys_addr_t addr, phys_addr_t end)
{
        pte_t *pte, *start_pte;

        start_pte = pte = pte_offset_kernel(pmd, addr);
        do {
                if (!pte_none(*pte)) {
                        kvm_set_pte(pte, __pte(0));
                        put_page(virt_to_page(pte));
                }
        } while (pte++, addr += PAGE_SIZE, addr != end);

        if (hyp_pte_table_empty(start_pte))
                clear_hyp_pmd_entry(pmd);
}

static void unmap_hyp_pmds(pud_t *pud, phys_addr_t addr, phys_addr_t end)
{
        phys_addr_t next;
        pmd_t *pmd, *start_pmd;

        start_pmd = pmd = pmd_offset(pud, addr);
        do {
                next = pmd_addr_end(addr, end);
                /* Hyp doesn't use huge pmds */
                if (!pmd_none(*pmd))
                        unmap_hyp_ptes(pmd, addr, next);
        } while (pmd++, addr = next, addr != end);

        if (hyp_pmd_table_empty(start_pmd))
                clear_hyp_pud_entry(pud);
}

static void unmap_hyp_puds(pgd_t *pgd, phys_addr_t addr, phys_addr_t end)
{
        phys_addr_t next;
        pud_t *pud, *start_pud;

        start_pud = pud = pud_offset(pgd, addr);
        do {
                next = pud_addr_end(addr, end);
                /* Hyp doesn't use huge puds */
                if (!pud_none(*pud))
                        unmap_hyp_pmds(pud, addr, next);
        } while (pud++, addr = next, addr != end);

        if (hyp_pud_table_empty(start_pud))
                clear_hyp_pgd_entry(pgd);
}

static unsigned int kvm_pgd_index(unsigned long addr, unsigned int ptrs_per_pgd)
{
        return (addr >> PGDIR_SHIFT) & (ptrs_per_pgd - 1);
}

static void __unmap_hyp_range(pgd_t *pgdp, unsigned long ptrs_per_pgd,
                              phys_addr_t start, u64 size)
{
        pgd_t *pgd;
        phys_addr_t addr = start, end = start + size;
        phys_addr_t next;

        /*
         * We don't unmap anything from HYP, except at the hyp tear down.
         * Hence, we don't have to invalidate the TLBs here.
         */
        pgd = pgdp + kvm_pgd_index(addr, ptrs_per_pgd);
        do {
                next = pgd_addr_end(addr, end);
                if (!pgd_none(*pgd))
                        unmap_hyp_puds(pgd, addr, next);
        } while (pgd++, addr = next, addr != end);
}

static void unmap_hyp_range(pgd_t *pgdp, phys_addr_t start, u64 size)
{
        __unmap_hyp_range(pgdp, PTRS_PER_PGD, start, size);
}

static void unmap_hyp_idmap_range(pgd_t *pgdp, phys_addr_t start, u64 size)
{
        __unmap_hyp_range(pgdp, __kvm_idmap_ptrs_per_pgd(), start, size);
}

/**
 * free_hyp_pgds - free Hyp-mode page tables
 *
 * Assumes hyp_pgd is a page table used strictly in Hyp-mode and
 * therefore contains either mappings in the kernel memory area (above
 * PAGE_OFFSET), or device mappings in the idmap range.
 *
 * boot_hyp_pgd should only map the idmap range, and is only used in
 * the extended idmap case.
 */
void free_hyp_pgds(void)
{
        pgd_t *id_pgd;

        mutex_lock(&kvm_hyp_pgd_mutex);

        id_pgd = boot_hyp_pgd ? boot_hyp_pgd : hyp_pgd;

        if (id_pgd) {
                /* In case we never called hyp_mmu_init() */
                if (!io_map_base)
                        io_map_base = hyp_idmap_start;
                unmap_hyp_idmap_range(id_pgd, io_map_base,
                                      hyp_idmap_start + PAGE_SIZE - io_map_base);
        }

        if (boot_hyp_pgd) {
                free_pages((unsigned long)boot_hyp_pgd, hyp_pgd_order);
                boot_hyp_pgd = NULL;
        }

        if (hyp_pgd) {
                unmap_hyp_range(hyp_pgd, kern_hyp_va(PAGE_OFFSET),
                                (uintptr_t)high_memory - PAGE_OFFSET);

                free_pages((unsigned long)hyp_pgd, hyp_pgd_order);
                hyp_pgd = NULL;
        }
        if (merged_hyp_pgd) {
                clear_page(merged_hyp_pgd);
                free_page((unsigned long)merged_hyp_pgd);
                merged_hyp_pgd = NULL;
        }

        mutex_unlock(&kvm_hyp_pgd_mutex);
}

static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start,
                                    unsigned long end, unsigned long pfn,
                                    pgprot_t prot)
{
        pte_t *pte;
        unsigned long addr;

        addr = start;
        do {
                pte = pte_offset_kernel(pmd, addr);
                kvm_set_pte(pte, kvm_pfn_pte(pfn, prot));
                get_page(virt_to_page(pte));
                pfn++;
        } while (addr += PAGE_SIZE, addr != end);
}

static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start,
                                   unsigned long end, unsigned long pfn,
                                   pgprot_t prot)
{
        pmd_t *pmd;
        pte_t *pte;
        unsigned long addr, next;

        addr = start;
        do {
                pmd = pmd_offset(pud, addr);

                BUG_ON(pmd_sect(*pmd));

                if (pmd_none(*pmd)) {
                        pte = pte_alloc_one_kernel(NULL);
                        if (!pte) {
                                kvm_err("Cannot allocate Hyp pte\n");
                                return -ENOMEM;
                        }
                        kvm_pmd_populate(pmd, pte);
                        get_page(virt_to_page(pmd));
                }

                next = pmd_addr_end(addr, end);

                create_hyp_pte_mappings(pmd, addr, next, pfn, prot);
                pfn += (next - addr) >> PAGE_SHIFT;
        } while (addr = next, addr != end);

        return 0;
}

static int create_hyp_pud_mappings(pgd_t *pgd, unsigned long start,
                                   unsigned long end, unsigned long pfn,
                                   pgprot_t prot)
{
        pud_t *pud;
        pmd_t *pmd;
        unsigned long addr, next;
        int ret;

        addr = start;
        do {
                pud = pud_offset(pgd, addr);

                if (pud_none_or_clear_bad(pud)) {
                        pmd = pmd_alloc_one(NULL, addr);
                        if (!pmd) {
                                kvm_err("Cannot allocate Hyp pmd\n");
                                return -ENOMEM;
                        }
                        kvm_pud_populate(pud, pmd);
                        get_page(virt_to_page(pud));
                }

                next = pud_addr_end(addr, end);
                ret = create_hyp_pmd_mappings(pud, addr, next, pfn, prot);
                if (ret)
                        return ret;
                pfn += (next - addr) >> PAGE_SHIFT;
        } while (addr = next, addr != end);

        return 0;
}

static int __create_hyp_mappings(pgd_t *pgdp, unsigned long ptrs_per_pgd,
                                 unsigned long start, unsigned long end,
                                 unsigned long pfn, pgprot_t prot)
{
        pgd_t *pgd;
        pud_t *pud;
        unsigned long addr, next;
        int err = 0;

        mutex_lock(&kvm_hyp_pgd_mutex);
        addr = start & PAGE_MASK;
        end = PAGE_ALIGN(end);
        do {
                pgd = pgdp + kvm_pgd_index(addr, ptrs_per_pgd);

                if (pgd_none(*pgd)) {
                        pud = pud_alloc_one(NULL, addr);
                        if (!pud) {
                                kvm_err("Cannot allocate Hyp pud\n");
                                err = -ENOMEM;
                                goto out;
                        }
                        kvm_pgd_populate(pgd, pud);
                        get_page(virt_to_page(pgd));
                }

                next = pgd_addr_end(addr, end);
                err = create_hyp_pud_mappings(pgd, addr, next, pfn, prot);
                if (err)
                        goto out;
                pfn += (next - addr) >> PAGE_SHIFT;
        } while (addr = next, addr != end);
out:
        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);
        }
}

/**
 * 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, pgprot_t 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;

        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(hyp_pgd, PTRS_PER_PGD,
                                            virt_addr, virt_addr + PAGE_SIZE,
                                            __phys_to_pfn(phys_addr),
                                            prot);
                if (err)
                        return err;
        }

        return 0;
}

static int __create_hyp_private_mapping(phys_addr_t phys_addr, size_t size,
                                        unsigned long *haddr, pgprot_t prot)
{
        pgd_t *pgd = hyp_pgd;
        unsigned long base;
        int ret = 0;

        mutex_lock(&kvm_hyp_pgd_mutex);

        /*
         * This assumes that we we have enough space below the idmap
         * page to allocate our VAs. If not, the check below 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 + offset_in_page(phys_addr));
        base = io_map_base - size;

        /*
         * 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))
                ret = -ENOMEM;
        else
                io_map_base = base;

        mutex_unlock(&kvm_hyp_pgd_mutex);

        if (ret)
                goto out;

        if (__kvm_cpu_uses_extended_idmap())
                pgd = boot_hyp_pgd;

        ret = __create_hyp_mappings(pgd, __kvm_idmap_ptrs_per_pgd(),
                                    base, base + size,
                                    __phys_to_pfn(phys_addr), prot);
        if (ret)
                goto out;

        *haddr = base + offset_in_page(phys_addr);

out:
        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;

        *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;
}

/**
 * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
 * @kvm:        The KVM struct pointer for the VM.
 *
 * Allocates only the stage-2 HW PGD level table(s) (can support either full
 * 40-bit input addresses or limited to 32-bit input addresses). Clears the
 * allocated pages.
 *
 * 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_alloc_stage2_pgd(struct kvm *kvm)
{
        pgd_t *pgd;

        if (kvm->arch.pgd != NULL) {
                kvm_err("kvm_arch already initialized?\n");
                return -EINVAL;
        }

        /* Allocate the HW PGD, making sure that each page gets its own refcount */
        pgd = alloc_pages_exact(stage2_pgd_size(kvm), GFP_KERNEL | __GFP_ZERO);
        if (!pgd)
                return -ENOMEM;

        kvm->arch.pgd = pgd;
        return 0;
}

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 = find_vma(current->mm, hva);
                hva_t vm_start, vm_end;

                if (!vma || vma->vm_start >= reg_end)
                        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, 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 reguler 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;

        idx = srcu_read_lock(&kvm->srcu);
        down_read(&current->mm->mmap_sem);
        spin_lock(&kvm->mmu_lock);

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

        spin_unlock(&kvm->mmu_lock);
        up_read(&current->mm->mmap_sem);
        srcu_read_unlock(&kvm->srcu, idx);
}

/**
 * kvm_free_stage2_pgd - free all stage-2 tables
 * @kvm:        The KVM struct pointer for the VM.
 *
 * Walks the level-1 page table pointed to by kvm->arch.pgd and frees all
 * underlying level-2 and level-3 tables before freeing the actual level-1 table
 * and setting the struct pointer to NULL.
 */
void kvm_free_stage2_pgd(struct kvm *kvm)
{
        void *pgd = NULL;

        spin_lock(&kvm->mmu_lock);
        if (kvm->arch.pgd) {
                unmap_stage2_range(kvm, 0, kvm_phys_size(kvm));
                pgd = READ_ONCE(kvm->arch.pgd);
                kvm->arch.pgd = NULL;
        }
        spin_unlock(&kvm->mmu_lock);

        /* Free the HW pgd, one page at a time */
        if (pgd)
                free_pages_exact(pgd, stage2_pgd_size(kvm));
}

static pud_t *stage2_get_pud(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
                             phys_addr_t addr)
{
        pgd_t *pgd;
        pud_t *pud;

        pgd = kvm->arch.pgd + stage2_pgd_index(kvm, addr);
        if (stage2_pgd_none(kvm, *pgd)) {
                if (!cache)
                        return NULL;
                pud = mmu_memory_cache_alloc(cache);
                stage2_pgd_populate(kvm, pgd, pud);
                get_page(virt_to_page(pgd));
        }

        return stage2_pud_offset(kvm, pgd, addr);
}

static pmd_t *stage2_get_pmd(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
                             phys_addr_t addr)
{
        pud_t *pud;
        pmd_t *pmd;

        pud = stage2_get_pud(kvm, cache, addr);
        if (!pud || stage2_pud_huge(kvm, *pud))
                return NULL;

        if (stage2_pud_none(kvm, *pud)) {
                if (!cache)
                        return NULL;
                pmd = mmu_memory_cache_alloc(cache);
                stage2_pud_populate(kvm, pud, pmd);
                get_page(virt_to_page(pud));
        }

        return stage2_pmd_offset(kvm, pud, addr);
}

static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
                               *cache, phys_addr_t addr, const pmd_t *new_pmd)
{
        pmd_t *pmd, old_pmd;

        pmd = stage2_get_pmd(kvm, cache, addr);
        VM_BUG_ON(!pmd);

        old_pmd = *pmd;
        if (pmd_present(old_pmd)) {
                /*
                 * Multiple vcpus faulting on the same PMD entry, can
                 * lead to them sequentially updating the PMD with the
                 * same value. Following the break-before-make
                 * (pmd_clear() followed by tlb_flush()) process can
                 * hinder forward progress due to refaults generated
                 * on missing translations.
                 *
                 * Skip updating the page table if the entry is
                 * unchanged.
                 */
                if (pmd_val(old_pmd) == pmd_val(*new_pmd))
                        return 0;

                /*
                 * Mapping in huge pages should only happen through a
                 * fault.  If a page is merged into a transparent huge
                 * page, the individual subpages of that huge page
                 * should be unmapped through MMU notifiers before we
                 * get here.
                 *
                 * Merging of CompoundPages is not supported; they
                 * should become splitting first, unmapped, merged,
                 * and mapped back in on-demand.
                 */
                VM_BUG_ON(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd));

                pmd_clear(pmd);
                kvm_tlb_flush_vmid_ipa(kvm, addr);
        } else {
                get_page(virt_to_page(pmd));
        }

        kvm_set_pmd(pmd, *new_pmd);
        return 0;
}

static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
                               phys_addr_t addr, const pud_t *new_pudp)
{
        pud_t *pudp, old_pud;

        pudp = stage2_get_pud(kvm, cache, addr);
        VM_BUG_ON(!pudp);

        old_pud = *pudp;

        /*
         * A large number of vcpus faulting on the same stage 2 entry,
         * can lead to a refault due to the
         * stage2_pud_clear()/tlb_flush(). Skip updating the page
         * tables if there is no change.
         */
        if (pud_val(old_pud) == pud_val(*new_pudp))
                return 0;

        if (stage2_pud_present(kvm, old_pud)) {
                stage2_pud_clear(kvm, pudp);
                kvm_tlb_flush_vmid_ipa(kvm, addr);
        } else {
                get_page(virt_to_page(pudp));
        }

        kvm_set_pud(pudp, *new_pudp);
        return 0;
}

/*
 * stage2_get_leaf_entry - walk the stage2 VM page tables and return
 * true if a valid and present leaf-entry is found. A pointer to the
 * leaf-entry is returned in the appropriate level variable - pudpp,
 * pmdpp, ptepp.
 */
static bool stage2_get_leaf_entry(struct kvm *kvm, phys_addr_t addr,
                                  pud_t **pudpp, pmd_t **pmdpp, pte_t **ptepp)
{
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;

        *pudpp = NULL;
        *pmdpp = NULL;
        *ptepp = NULL;

        pudp = stage2_get_pud(kvm, NULL, addr);
        if (!pudp || stage2_pud_none(kvm, *pudp) || !stage2_pud_present(kvm, *pudp))
                return false;

        if (stage2_pud_huge(kvm, *pudp)) {
                *pudpp = pudp;
                return true;
        }

        pmdp = stage2_pmd_offset(kvm, pudp, addr);
        if (!pmdp || pmd_none(*pmdp) || !pmd_present(*pmdp))
                return false;

        if (pmd_thp_or_huge(*pmdp)) {
                *pmdpp = pmdp;
                return true;
        }

        ptep = pte_offset_kernel(pmdp, addr);
        if (!ptep || pte_none(*ptep) || !pte_present(*ptep))
                return false;

        *ptepp = ptep;
        return true;
}

static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)
{
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;
        bool found;

        found = stage2_get_leaf_entry(kvm, addr, &pudp, &pmdp, &ptep);
        if (!found)
                return false;

        if (pudp)
                return kvm_s2pud_exec(pudp);
        else if (pmdp)
                return kvm_s2pmd_exec(pmdp);
        else
                return kvm_s2pte_exec(ptep);
}

static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
                          phys_addr_t addr, const pte_t *new_pte,
                          unsigned long flags)
{
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte, old_pte;
        bool iomap = flags & KVM_S2PTE_FLAG_IS_IOMAP;
        bool logging_active = flags & KVM_S2_FLAG_LOGGING_ACTIVE;

        VM_BUG_ON(logging_active && !cache);

        /* Create stage-2 page table mapping - Levels 0 and 1 */
        pud = stage2_get_pud(kvm, cache, addr);
        if (!pud) {
                /*
                 * Ignore calls from kvm_set_spte_hva for unallocated
                 * address ranges.
                 */
                return 0;
        }

        /*
         * While dirty page logging - dissolve huge PUD, then continue
         * on to allocate page.
         */
        if (logging_active)
                stage2_dissolve_pud(kvm, addr, pud);

        if (stage2_pud_none(kvm, *pud)) {
                if (!cache)
                        return 0; /* ignore calls from kvm_set_spte_hva */
                pmd = mmu_memory_cache_alloc(cache);
                stage2_pud_populate(kvm, pud, pmd);
                get_page(virt_to_page(pud));
        }

        pmd = stage2_pmd_offset(kvm, pud, addr);
        if (!pmd) {
                /*
                 * Ignore calls from kvm_set_spte_hva for unallocated
                 * address ranges.
                 */
                return 0;
        }

        /*
         * While dirty page logging - dissolve huge PMD, then continue on to
         * allocate page.
         */
        if (logging_active)
                stage2_dissolve_pmd(kvm, addr, pmd);

        /* Create stage-2 page mappings - Level 2 */
        if (pmd_none(*pmd)) {
                if (!cache)
                        return 0; /* ignore calls from kvm_set_spte_hva */
                pte = mmu_memory_cache_alloc(cache);
                kvm_pmd_populate(pmd, pte);
                get_page(virt_to_page(pmd));
        }

        pte = pte_offset_kernel(pmd, addr);

        if (iomap && pte_present(*pte))
                return -EFAULT;

        /* Create 2nd stage page table mapping - Level 3 */
        old_pte = *pte;
        if (pte_present(old_pte)) {
                /* Skip page table update if there is no change */
                if (pte_val(old_pte) == pte_val(*new_pte))
                        return 0;

                kvm_set_pte(pte, __pte(0));
                kvm_tlb_flush_vmid_ipa(kvm, addr);
        } else {
                get_page(virt_to_page(pte));
        }

        kvm_set_pte(pte, *new_pte);
        return 0;
}

#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static int stage2_ptep_test_and_clear_young(pte_t *pte)
{
        if (pte_young(*pte)) {
                *pte = pte_mkold(*pte);
                return 1;
        }
        return 0;
}
#else
static int stage2_ptep_test_and_clear_young(pte_t *pte)
{
        return __ptep_test_and_clear_young(pte);
}
#endif

static int stage2_pmdp_test_and_clear_young(pmd_t *pmd)
{
        return stage2_ptep_test_and_clear_young((pte_t *)pmd);
}

static int stage2_pudp_test_and_clear_young(pud_t *pud)
{
        return stage2_ptep_test_and_clear_young((pte_t *)pud);
}

/**
 * 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
 */
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, end;
        int ret = 0;
        unsigned long pfn;
        struct kvm_mmu_memory_cache cache = { 0, };

        end = (guest_ipa + size + PAGE_SIZE - 1) & PAGE_MASK;
        pfn = __phys_to_pfn(pa);

        for (addr = guest_ipa; addr < end; addr += PAGE_SIZE) {
                pte_t pte = kvm_pfn_pte(pfn, PAGE_S2_DEVICE);

                if (writable)
                        pte = kvm_s2pte_mkwrite(pte);

                ret = mmu_topup_memory_cache(&cache,
                                             kvm_mmu_cache_min_pages(kvm),
                                             KVM_NR_MEM_OBJS);
                if (ret)
                        goto out;
                spin_lock(&kvm->mmu_lock);
                ret = stage2_set_pte(kvm, &cache, addr, &pte,
                                                KVM_S2PTE_FLAG_IS_IOMAP);
                spin_unlock(&kvm->mmu_lock);
                if (ret)
                        goto out;

                pfn++;
        }

out:
        mmu_free_memory_cache(&cache);
        return ret;
}

static bool transparent_hugepage_adjust(kvm_pfn_t *pfnp, phys_addr_t *ipap)
{
        kvm_pfn_t pfn = *pfnp;
        gfn_t gfn = *ipap >> PAGE_SHIFT;
        struct page *page = pfn_to_page(pfn);

        /*
         * PageTransCompoundMap() returns true for THP and
         * hugetlbfs. Make sure the adjustment is done only for THP
         * pages.
         */
        if (!PageHuge(page) && PageTransCompoundMap(page)) {
                unsigned long mask;
                /*
                 * The address we faulted on is backed by a transparent huge
                 * page.  However, because we map the compound huge page and
                 * not the individual tail page, we need to transfer the
                 * refcount to the head page.  We have to be careful that the
                 * THP doesn't start to split while we are adjusting the
                 * refcounts.
                 *
                 * We are sure this doesn't happen, because mmu_notifier_retry
                 * was successful and we are holding the mmu_lock, so if this
                 * THP is trying to split, it will be blocked in the mmu
                 * notifier before touching any of the pages, specifically
                 * before being able to call __split_huge_page_refcount().
                 *
                 * We can therefore safely transfer the refcount from PG_tail
                 * to PG_head and switch the pfn from a tail page to the head
                 * page accordingly.
                 */
                mask = PTRS_PER_PMD - 1;
                VM_BUG_ON((gfn & mask) != (pfn & mask));
                if (pfn & mask) {
                        *ipap &= PMD_MASK;
                        kvm_release_pfn_clean(pfn);
                        pfn &= ~mask;
                        kvm_get_pfn(pfn);
                        *pfnp = pfn;
                }

                return true;
        }

        return false;
}

static bool kvm_is_write_fault(struct kvm_vcpu *vcpu)
{
        if (kvm_vcpu_trap_is_iabt(vcpu))
                return false;

        return kvm_vcpu_dabt_iswrite(vcpu);
}

/**
 * stage2_wp_ptes - write protect PMD range
 * @pmd:        pointer to pmd entry
 * @addr:       range start address
 * @end:        range end address
 */
static void stage2_wp_ptes(pmd_t *pmd, phys_addr_t addr, phys_addr_t end)
{
        pte_t *pte;

        pte = pte_offset_kernel(pmd, addr);
        do {
                if (!pte_none(*pte)) {
                        if (!kvm_s2pte_readonly(pte))
                                kvm_set_s2pte_readonly(pte);
                }
        } while (pte++, addr += PAGE_SIZE, addr != end);
}

/**
 * stage2_wp_pmds - write protect PUD range
 * kvm:         kvm instance for the VM
 * @pud:        pointer to pud entry
 * @addr:       range start address
 * @end:        range end address
 */
static void stage2_wp_pmds(struct kvm *kvm, pud_t *pud,
                           phys_addr_t addr, phys_addr_t end)
{
        pmd_t *pmd;
        phys_addr_t next;

        pmd = stage2_pmd_offset(kvm, pud, addr);

        do {
                next = stage2_pmd_addr_end(kvm, addr, end);
                if (!pmd_none(*pmd)) {
                        if (pmd_thp_or_huge(*pmd)) {
                                if (!kvm_s2pmd_readonly(pmd))
                                        kvm_set_s2pmd_readonly(pmd);
                        } else {
                                stage2_wp_ptes(pmd, addr, next);
                        }
                }
        } while (pmd++, addr = next, addr != end);
}

/**
  * stage2_wp_puds - write protect PGD range
  * @pgd:       pointer to pgd entry
  * @addr:      range start address
  * @end:       range end address
  *
  * Process PUD entries, for a huge PUD we cause a panic.
  */
static void  stage2_wp_puds(struct kvm *kvm, pgd_t *pgd,
                            phys_addr_t addr, phys_addr_t end)
{
        pud_t *pud;
        phys_addr_t next;

        pud = stage2_pud_offset(kvm, pgd, addr);
        do {
                next = stage2_pud_addr_end(kvm, addr, end);
                if (!stage2_pud_none(kvm, *pud)) {
                        if (stage2_pud_huge(kvm, *pud)) {
                                if (!kvm_s2pud_readonly(pud))
                                        kvm_set_s2pud_readonly(pud);
                        } else {
                                stage2_wp_pmds(kvm, pud, addr, next);
                        }
                }
        } while (pud++, addr = next, addr != end);
}

/**
 * stage2_wp_range() - write protect stage2 memory region range
 * @kvm:        The KVM pointer
 * @addr:       Start address of range
 * @end:        End address of range
 */
static void stage2_wp_range(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
{
        pgd_t *pgd;
        phys_addr_t next;

        pgd = kvm->arch.pgd + stage2_pgd_index(kvm, addr);
        do {
                /*
                 * 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.
                 */
                cond_resched_lock(&kvm->mmu_lock);
                if (!READ_ONCE(kvm->arch.pgd))
                        break;
                next = stage2_pgd_addr_end(kvm, addr, end);
                if (stage2_pgd_present(kvm, *pgd))
                        stage2_wp_puds(kvm, pgd, addr, next);
        } while (pgd++, addr = next, addr != end);
}

/**
 * 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.
 */
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 = memslot->base_gfn << PAGE_SHIFT;
        phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;

        spin_lock(&kvm->mmu_lock);
        stage2_wp_range(kvm, start, end);
        spin_unlock(&kvm->mmu_lock);
        kvm_flush_remote_tlbs(kvm);
}

/**
 * kvm_mmu_write_protect_pt_masked() - write protect dirty pages
 * @kvm:        The KVM pointer
 * @slot:       The memory slot associated with mask
 * @gfn_offset: The gfn offset in memory slot
 * @mask:       The mask of dirty pages at offset 'gfn_offset' in this memory
 *              slot to be write protected
 *
 * Walks bits set in mask write protects the associated pte's. Caller must
 * acquire kvm_mmu_lock.
 */
static void kvm_mmu_write_protect_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;

        stage2_wp_range(kvm, start, end);
}

/*
 * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected
 * dirty pages.
 *
 * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to
 * enable dirty logging for them.
 */
void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
                struct kvm_memory_slot *slot,
                gfn_t gfn_offset, unsigned long mask)
{
        kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
}

static void clean_dcache_guest_page(kvm_pfn_t pfn, unsigned long size)
{
        __clean_dcache_guest_page(pfn, size);
}

static void invalidate_icache_guest_page(kvm_pfn_t pfn, unsigned long size)
{
        __invalidate_icache_guest_page(pfn, size);
}

static void kvm_send_hwpoison_signal(unsigned long address,
                                     struct vm_area_struct *vma)
{
        short lsb;

        if (is_vm_hugetlb_page(vma))
                lsb = huge_page_shift(hstate_vma(vma));
        else
                lsb = PAGE_SHIFT;

        send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, current);
}

static bool fault_supports_stage2_pmd_mappings(struct kvm_memory_slot *memslot,
                                               unsigned long hva)
{
        gpa_t gpa_start, gpa_end;
        hva_t uaddr_start, uaddr_end;
        size_t size;

        size = memslot->npages * PAGE_SIZE;

        gpa_start = memslot->base_gfn << PAGE_SHIFT;
        gpa_end = gpa_start + size;

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

        /*
         * Pages belonging to memslots that don't have the same alignment
         * within a PMD for userspace and IPA cannot be mapped with stage-2
         * PMD entries, because we'll end up mapping the wrong pages.
         *
         * Consider a layout like the following:
         *
         *    memslot->userspace_addr:
         *    +-----+--------------------+--------------------+---+
         *    |abcde|fgh  Stage-1 PMD    |    Stage-1 PMD   tv|xyz|
         *    +-----+--------------------+--------------------+---+
         *
         *    memslot->base_gfn << PAGE_SIZE:
         *      +---+--------------------+--------------------+-----+
         *      |abc|def  Stage-2 PMD    |    Stage-2 PMD     |tvxyz|
         *      +---+--------------------+--------------------+-----+
         *
         * If we create those stage-2 PMDs, we'll end up with this incorrect
         * mapping:
         *   d -> f
         *   e -> g
         *   f -> h
         */
        if ((gpa_start & ~S2_PMD_MASK) != (uaddr_start & ~S2_PMD_MASK))
                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 PMD size mappings
         * for the beginning and end of a non-PMD aligned and non-PMD 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 & S2_PMD_MASK) >= uaddr_start &&
               (hva & S2_PMD_MASK) + S2_PMD_SIZE <= uaddr_end;
}

static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
                          struct kvm_memory_slot *memslot, unsigned long hva,
                          unsigned long fault_status)
{
        int ret;
        bool write_fault, writable, force_pte = false;
        bool exec_fault, needs_exec;
        unsigned long mmu_seq;
        gfn_t gfn = fault_ipa >> PAGE_SHIFT;
        struct kvm *kvm = vcpu->kvm;
        struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
        struct vm_area_struct *vma;
        kvm_pfn_t pfn;
        pgprot_t mem_type = PAGE_S2;
        bool logging_active = memslot_is_logging(memslot);
        unsigned long vma_pagesize, flags = 0;

        write_fault = kvm_is_write_fault(vcpu);
        exec_fault = kvm_vcpu_trap_is_iabt(vcpu);
        VM_BUG_ON(write_fault && exec_fault);

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

        if (!fault_supports_stage2_pmd_mappings(memslot, hva))
                force_pte = true;

        if (logging_active)
                force_pte = true;

        /* Let's check if we will get back a huge page backed by hugetlbfs */
        down_read(&current->mm->mmap_sem);
        vma = find_vma_intersection(current->mm, hva, hva + 1);
        if (unlikely(!vma)) {
                kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
                up_read(&current->mm->mmap_sem);
                return -EFAULT;
        }

        vma_pagesize = vma_kernel_pagesize(vma);
        /*
         * PUD level may not exist for a VM but PMD is guaranteed to
         * exist.
         */
        if ((vma_pagesize == PMD_SIZE ||
             (vma_pagesize == PUD_SIZE && kvm_stage2_has_pud(kvm))) &&
            !force_pte) {
                gfn = (fault_ipa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
        }
        up_read(&current->mm->mmap_sem);

        /* We need minimum second+third level pages */
        ret = mmu_topup_memory_cache(memcache, kvm_mmu_cache_min_pages(kvm),
                                     KVM_NR_MEM_OBJS);
        if (ret)
                return ret;

        mmu_seq = vcpu->kvm->mmu_notifier_seq;
        /*
         * Ensure the read of mmu_notifier_seq happens before we call
         * gfn_to_pfn_prot (which calls get_user_pages), so that we don't risk
         * the page we just got a reference to gets unmapped before we have a
         * chance to grab the mmu_lock, which ensure that if the page gets
         * unmapped afterwards, the call to kvm_unmap_hva will take it away
         * from us again properly. This smp_rmb() interacts with the smp_wmb()
         * in kvm_mmu_notifier_invalidate_<page|range_end>.
         */
        smp_rmb();

        pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writable);
        if (pfn == KVM_PFN_ERR_HWPOISON) {
                kvm_send_hwpoison_signal(hva, vma);
                return 0;
        }
        if (is_error_noslot_pfn(pfn))
                return -EFAULT;

        if (kvm_is_device_pfn(pfn)) {
                mem_type = PAGE_S2_DEVICE;
                flags |= KVM_S2PTE_FLAG_IS_IOMAP;
        } else if (logging_active) {
                /*
                 * Faults on pages in a memslot with logging enabled
                 * should not be mapped with huge pages (it introduces churn
                 * and performance degradation), so force a pte mapping.
                 */
                flags |= KVM_S2_FLAG_LOGGING_ACTIVE;

                /*
                 * Only actually map the page as writable if this was a write
                 * fault.
                 */
                if (!write_fault)
                        writable = false;
        }

        spin_lock(&kvm->mmu_lock);
        if (mmu_notifier_retry(kvm, mmu_seq))
                goto out_unlock;

        if (vma_pagesize == PAGE_SIZE && !force_pte) {
                /*
                 * Only PMD_SIZE transparent hugepages(THP) are
                 * currently supported. This code will need to be
                 * updated to support other THP sizes.
                 */
                if (transparent_hugepage_adjust(&pfn, &fault_ipa))
                        vma_pagesize = PMD_SIZE;
        }

        if (writable)
                kvm_set_pfn_dirty(pfn);

        if (fault_status != FSC_PERM)
                clean_dcache_guest_page(pfn, vma_pagesize);

        if (exec_fault)
                invalidate_icache_guest_page(pfn, vma_pagesize);

        /*
         * If we took an execution fault we have made the
         * icache/dcache coherent above and should now let the s2
         * mapping be executable.
         *
         * Write faults (!exec_fault && FSC_PERM) are orthogonal to
         * execute permissions, and we preserve whatever we have.
         */
        needs_exec = exec_fault ||
                (fault_status == FSC_PERM && stage2_is_exec(kvm, fault_ipa));

        if (vma_pagesize == PUD_SIZE) {
                pud_t new_pud = kvm_pfn_pud(pfn, mem_type);

                new_pud = kvm_pud_mkhuge(new_pud);
                if (writable)
                        new_pud = kvm_s2pud_mkwrite(new_pud);

                if (needs_exec)
                        new_pud = kvm_s2pud_mkexec(new_pud);

                ret = stage2_set_pud_huge(kvm, memcache, fault_ipa, &new_pud);
        } else if (vma_pagesize == PMD_SIZE) {
                pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);

                new_pmd = kvm_pmd_mkhuge(new_pmd);

                if (writable)
                        new_pmd = kvm_s2pmd_mkwrite(new_pmd);

                if (needs_exec)
                        new_pmd = kvm_s2pmd_mkexec(new_pmd);

                ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
        } else {
                pte_t new_pte = kvm_pfn_pte(pfn, mem_type);

                if (writable) {
                        new_pte = kvm_s2pte_mkwrite(new_pte);
                        mark_page_dirty(kvm, gfn);
                }

                if (needs_exec)
                        new_pte = kvm_s2pte_mkexec(new_pte);

                ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, flags);
        }

out_unlock:
        spin_unlock(&kvm->mmu_lock);
        kvm_set_pfn_accessed(pfn);
        kvm_release_pfn_clean(pfn);
        return ret;
}

/*
 * Resolve the access fault by making the page young again.
 * Note that because the faulting entry is guaranteed not to be
 * cached in the TLB, we don't need to invalidate anything.
 * Only the HW Access Flag updates are supported for Stage 2 (no DBM),
 * so there is no need for atomic (pte|pmd)_mkyoung operations.
 */
static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
{
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
        kvm_pfn_t pfn;
        bool pfn_valid = false;

        trace_kvm_access_fault(fault_ipa);

        spin_lock(&vcpu->kvm->mmu_lock);

        if (!stage2_get_leaf_entry(vcpu->kvm, fault_ipa, &pud, &pmd, &pte))
                goto out;

        if (pud) {              /* HugeTLB */
                *pud = kvm_s2pud_mkyoung(*pud);
                pfn = kvm_pud_pfn(*pud);
                pfn_valid = true;
        } else  if (pmd) {      /* THP, HugeTLB */
                *pmd = pmd_mkyoung(*pmd);
                pfn = pmd_pfn(*pmd);
                pfn_valid = true;
        } else {
                *pte = pte_mkyoung(*pte);       /* Just a page... */
                pfn = pte_pfn(*pte);
                pfn_valid = true;
        }

out:
        spin_unlock(&vcpu->kvm->mmu_lock);
        if (pfn_valid)
                kvm_set_pfn_accessed(pfn);
}

/**
 * kvm_handle_guest_abort - handles all 2nd stage aborts
 * @vcpu:       the VCPU pointer
 * @run:        the kvm_run structure
 *
 * 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, struct kvm_run *run)
{
        unsigned long fault_status;
        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;

        fault_status = kvm_vcpu_trap_get_fault_type(vcpu);

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

        /* Synchronous External Abort? */
        if (kvm_vcpu_dabt_isextabt(vcpu)) {
                /*
                 * For RAS the host kernel may handle this abort.
                 * There is no need to pass the error into the guest.
                 */
                if (!handle_guest_sea(fault_ipa, kvm_vcpu_get_hsr(vcpu)))
                        return 1;

                if (unlikely(!is_iabt)) {
                        kvm_inject_vabt(vcpu);
                        return 1;
                }
        }

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

        /* Check the stage-2 fault is trans. fault or write fault */
        if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
            fault_status != FSC_ACCESS) {
                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_hsr(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)) {
                if (is_iabt) {
                        /* Prefetch Abort on I/O address */
                        kvm_inject_pabt(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_vcpu_dabt_is_cm(vcpu)) {
                        kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(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, run, 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->kvm));

        if (fault_status == FSC_ACCESS) {
                handle_access_fault(vcpu, fault_ipa);
                ret = 1;
                goto out_unlock;
        }

        ret = user_mem_abort(vcpu, fault_ipa, memslot, hva, fault_status);
        if (ret == 0)
                ret = 1;
out_unlock:
        srcu_read_unlock(&vcpu->kvm->srcu, idx);
        return ret;
}

static int handle_hva_to_gpa(struct kvm *kvm,
                             unsigned long start,
                             unsigned long end,
                             int (*handler)(struct kvm *kvm,
                                            gpa_t gpa, u64 size,
                                            void *data),
                             void *data)
{
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;
        int ret = 0;

        slots = kvm_memslots(kvm);

        /* we only care about the pages that the guest sees */
        kvm_for_each_memslot(memslot, slots) {
                unsigned long hva_start, hva_end;
                gfn_t gpa;

                hva_start = max(start, memslot->userspace_addr);
                hva_end = min(end, memslot->userspace_addr +
                                        (memslot->npages << PAGE_SHIFT));
                if (hva_start >= hva_end)
                        continue;

                gpa = hva_to_gfn_memslot(hva_start, memslot) << PAGE_SHIFT;
                ret |= handler(kvm, gpa, (u64)(hva_end - hva_start), data);
        }

        return ret;
}

static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data)
{
        unmap_stage2_range(kvm, gpa, size);
        return 0;
}

int kvm_unmap_hva_range(struct kvm *kvm,
                        unsigned long start, unsigned long end)
{
        if (!kvm->arch.pgd)
                return 0;

        trace_kvm_unmap_hva_range(start, end);
        handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL);
        return 0;
}

static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data)
{
        pte_t *pte = (pte_t *)data;

        WARN_ON(size != PAGE_SIZE);
        /*
         * We can always call stage2_set_pte with KVM_S2PTE_FLAG_LOGGING_ACTIVE
         * flag clear because MMU notifiers will have unmapped a huge PMD before
         * calling ->change_pte() (which in turn calls kvm_set_spte_hva()) and
         * therefore stage2_set_pte() never needs to clear out a huge PMD
         * through this calling path.
         */
        stage2_set_pte(kvm, NULL, gpa, pte, 0);
        return 0;
}


int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
{
        unsigned long end = hva + PAGE_SIZE;
        kvm_pfn_t pfn = pte_pfn(pte);
        pte_t stage2_pte;

        if (!kvm->arch.pgd)
                return 0;

        trace_kvm_set_spte_hva(hva);

        /*
         * We've moved a page around, probably through CoW, so let's treat it
         * just like a translation fault and clean the cache to the PoC.
         */
        clean_dcache_guest_page(pfn, PAGE_SIZE);
        stage2_pte = kvm_pfn_pte(pfn, PAGE_S2);
        handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &stage2_pte);

        return 0;
}

static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data)
{
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
        if (!stage2_get_leaf_entry(kvm, gpa, &pud, &pmd, &pte))
                return 0;

        if (pud)
                return stage2_pudp_test_and_clear_young(pud);
        else if (pmd)
                return stage2_pmdp_test_and_clear_young(pmd);
        else
                return stage2_ptep_test_and_clear_young(pte);
}

static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data)
{
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
        if (!stage2_get_leaf_entry(kvm, gpa, &pud, &pmd, &pte))
                return 0;

        if (pud)
                return kvm_s2pud_young(*pud);
        else if (pmd)
                return pmd_young(*pmd);
        else
                return pte_young(*pte);
}

int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
{
        if (!kvm->arch.pgd)
                return 0;
        trace_kvm_age_hva(start, end);
        return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL);
}

int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
{
        if (!kvm->arch.pgd)
                return 0;
        trace_kvm_test_age_hva(hva);
        return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL);
}

void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
        mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
}

phys_addr_t kvm_mmu_get_httbr(void)
{
        if (__kvm_cpu_uses_extended_idmap())
                return virt_to_phys(merged_hyp_pgd);
        else
                return virt_to_phys(hyp_pgd);
}

phys_addr_t kvm_get_idmap_vector(void)
{
        return hyp_idmap_vector;
}

static int kvm_map_idmap_text(pgd_t *pgd)
{
        int err;

        /* Create the idmap in the boot page tables */
        err =   __create_hyp_mappings(pgd, __kvm_idmap_ptrs_per_pgd(),
                                      hyp_idmap_start, hyp_idmap_end,
                                      __phys_to_pfn(hyp_idmap_start),
                                      PAGE_HYP_EXEC);
        if (err)
                kvm_err("Failed to idmap %lx-%lx\n",
                        hyp_idmap_start, hyp_idmap_end);

        return err;
}

int kvm_mmu_init(void)
{
        int err;

        hyp_idmap_start = kvm_virt_to_phys(__hyp_idmap_text_start);
        hyp_idmap_start = ALIGN_DOWN(hyp_idmap_start, PAGE_SIZE);
        hyp_idmap_end = kvm_virt_to_phys(__hyp_idmap_text_end);
        hyp_idmap_end = ALIGN(hyp_idmap_end, PAGE_SIZE);
        hyp_idmap_vector = kvm_virt_to_phys(__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);

        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_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, hyp_pgd_order);
        if (!hyp_pgd) {
                kvm_err("Hyp mode PGD not allocated\n");
                err = -ENOMEM;
                goto out;
        }

        if (__kvm_cpu_uses_extended_idmap()) {
                boot_hyp_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                                         hyp_pgd_order);
                if (!boot_hyp_pgd) {
                        kvm_err("Hyp boot PGD not allocated\n");
                        err = -ENOMEM;
                        goto out;
                }

                err = kvm_map_idmap_text(boot_hyp_pgd);
                if (err)
                        goto out;

                merged_hyp_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
                if (!merged_hyp_pgd) {
                        kvm_err("Failed to allocate extra HYP pgd\n");
                        goto out;
                }
                __kvm_extend_hypmap(boot_hyp_pgd, hyp_pgd, merged_hyp_pgd,
                                    hyp_idmap_start);
        } else {
                err = kvm_map_idmap_text(hyp_pgd);
                if (err)
                        goto out;
        }

        io_map_base = hyp_idmap_start;
        return 0;
out:
        free_hyp_pgds();
        return err;
}

void kvm_arch_commit_memory_region(struct kvm *kvm,
                                   const struct kvm_userspace_memory_region *mem,
                                   const struct kvm_memory_slot *old,
                                   const struct kvm_memory_slot *new,
                                   enum kvm_mr_change change)
{
        /*
         * At this point memslot has been committed and there is an
         * allocated dirty_bitmap[], dirty pages will be be tracked while the
         * memory slot is write protected.
         */
        if (change != KVM_MR_DELETE && mem->flags & KVM_MEM_LOG_DIRTY_PAGES)
                kvm_mmu_wp_memory_region(kvm, mem->slot);
}

int kvm_arch_prepare_memory_region(struct kvm *kvm,
                                   struct kvm_memory_slot *memslot,
                                   const struct kvm_userspace_memory_region *mem,
                                   enum kvm_mr_change change)
{
        hva_t hva = mem->userspace_addr;
        hva_t reg_end = hva + mem->memory_size;
        bool writable = !(mem->flags & KVM_MEM_READONLY);
        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 (memslot->base_gfn + memslot->npages >=
            (kvm_phys_size(kvm) >> PAGE_SHIFT))
                return -EFAULT;

        down_read(&current->mm->mmap_sem);
        /*
         * A memory region could potentially cover multiple VMAs, and any holes
         * between them, so iterate over all of them to find out if we can map
         * any of them right now.
         *
         *     +--------------------------------------------+
         * +---------------+----------------+   +----------------+
         * |   : VMA 1     |      VMA 2     |   |    VMA 3  :    |
         * +---------------+----------------+   +----------------+
         *     |               memory region                |
         *     +--------------------------------------------+
         */
        do {
                struct vm_area_struct *vma = find_vma(current->mm, hva);
                hva_t vm_start, vm_end;

                if (!vma || vma->vm_start >= reg_end)
                        break;

                /*
                 * Mapping a read-only VMA is only allowed if the
                 * memory region is configured as read-only.
                 */
                if (writable && !(vma->vm_flags & VM_WRITE)) {
                        ret = -EPERM;
                        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 = mem->guest_phys_addr +
                                    (vm_start - mem->userspace_addr);
                        phys_addr_t pa;

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

                        /* IO region dirty page logging not allowed */
                        if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) {
                                ret = -EINVAL;
                                goto out;
                        }

                        ret = kvm_phys_addr_ioremap(kvm, gpa, pa,
                                                    vm_end - vm_start,
                                                    writable);
                        if (ret)
                                break;
                }
                hva = vm_end;
        } while (hva < reg_end);

        if (change == KVM_MR_FLAGS_ONLY)
                goto out;

        spin_lock(&kvm->mmu_lock);
        if (ret)
                unmap_stage2_range(kvm, mem->guest_phys_addr, mem->memory_size);
        else
                stage2_flush_memslot(kvm, memslot);
        spin_unlock(&kvm->mmu_lock);
out:
        up_read(&current->mm->mmap_sem);
        return ret;
}

void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
                           struct kvm_memory_slot *dont)
{
}

int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
                            unsigned long npages)
{
        return 0;
}

void kvm_arch_memslots_updated(struct kvm *kvm, struct kvm_memslots *slots)
{
}

void kvm_arch_flush_shadow_all(struct kvm *kvm)
{
        kvm_free_stage2_pgd(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;

        spin_lock(&kvm->mmu_lock);
        unmap_stage2_range(kvm, gpa, size);
        spin_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);
}