Initial commit: OpenHarmony-v4.0-ReleaseOpenHarmony-v4.0-Release

1 files changed, 1236 insertions, 0 deletions

diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
new file mode 100644
index 000000000..28c366d30
--- /dev/null
+++ b/arch/mips/kvm/mmu.c
@@ -0,0 +1,1236 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * KVM/MIPS MMU handling in the KVM module.
+ *
+ * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
+ * Authors: Sanjay Lal <sanjayl@kymasys.com>
+ */
+
+#include <linux/highmem.h>
+#include <linux/kvm_host.h>
+#include <linux/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/pgalloc.h>
+
+/*
+ * KVM_MMU_CACHE_MIN_PAGES is the number of GPA page table translation levels
+ * for which pages need to be cached.
+ */
+#if defined(__PAGETABLE_PMD_FOLDED)
+#define KVM_MMU_CACHE_MIN_PAGES 1
+#else
+#define KVM_MMU_CACHE_MIN_PAGES 2
+#endif
+
+void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)
+{
+        kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
+}
+
+/**
+ * kvm_pgd_init() - Initialise KVM GPA page directory.
+ * @page:       Pointer to page directory (PGD) for KVM GPA.
+ *
+ * Initialise a KVM GPA page directory with pointers to the invalid table, i.e.
+ * representing no mappings. This is similar to pgd_init(), however it
+ * initialises all the page directory pointers, not just the ones corresponding
+ * to the userland address space (since it is for the guest physical address
+ * space rather than a virtual address space).
+ */
+static void kvm_pgd_init(void *page)
+{
+        unsigned long *p, *end;
+        unsigned long entry;
+
+#ifdef __PAGETABLE_PMD_FOLDED
+        entry = (unsigned long)invalid_pte_table;
+#else
+        entry = (unsigned long)invalid_pmd_table;
+#endif
+
+        p = (unsigned long *)page;
+        end = p + PTRS_PER_PGD;
+
+        do {
+                p[0] = entry;
+                p[1] = entry;
+                p[2] = entry;
+                p[3] = entry;
+                p[4] = entry;
+                p += 8;
+                p[-3] = entry;
+                p[-2] = entry;
+                p[-1] = entry;
+        } while (p != end);
+}
+
+/**
+ * kvm_pgd_alloc() - Allocate and initialise a KVM GPA page directory.
+ *
+ * Allocate a blank KVM GPA page directory (PGD) for representing guest physical
+ * to host physical page mappings.
+ *
+ * Returns:     Pointer to new KVM GPA page directory.
+ *              NULL on allocation failure.
+ */
+pgd_t *kvm_pgd_alloc(void)
+{
+        pgd_t *ret;
+
+        ret = (pgd_t *)__get_free_pages(GFP_KERNEL, PGD_ORDER);
+        if (ret)
+                kvm_pgd_init(ret);
+
+        return ret;
+}
+
+/**
+ * kvm_mips_walk_pgd() - Walk page table with optional allocation.
+ * @pgd:        Page directory pointer.
+ * @addr:       Address to index page table using.
+ * @cache:      MMU page cache to allocate new page tables from, or NULL.
+ *
+ * Walk the page tables pointed to by @pgd to find the PTE corresponding to the
+ * address @addr. If page tables don't exist for @addr, they will be created
+ * from the MMU cache if @cache is not NULL.
+ *
+ * Returns:     Pointer to pte_t corresponding to @addr.
+ *              NULL if a page table doesn't exist for @addr and !@cache.
+ *              NULL if a page table allocation failed.
+ */
+static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
+                                unsigned long addr)
+{
+        p4d_t *p4d;
+        pud_t *pud;
+        pmd_t *pmd;
+
+        pgd += pgd_index(addr);
+        if (pgd_none(*pgd)) {
+                /* Not used on MIPS yet */
+                BUG();
+                return NULL;
+        }
+        p4d = p4d_offset(pgd, addr);
+        pud = pud_offset(p4d, addr);
+        if (pud_none(*pud)) {
+                pmd_t *new_pmd;
+
+                if (!cache)
+                        return NULL;
+                new_pmd = kvm_mmu_memory_cache_alloc(cache);
+                pmd_init((unsigned long)new_pmd,
+                         (unsigned long)invalid_pte_table);
+                pud_populate(NULL, pud, new_pmd);
+        }
+        pmd = pmd_offset(pud, addr);
+        if (pmd_none(*pmd)) {
+                pte_t *new_pte;
+
+                if (!cache)
+                        return NULL;
+                new_pte = kvm_mmu_memory_cache_alloc(cache);
+                clear_page(new_pte);
+                pmd_populate_kernel(NULL, pmd, new_pte);
+        }
+        return pte_offset_kernel(pmd, addr);
+}
+
+/* Caller must hold kvm->mm_lock */
+static pte_t *kvm_mips_pte_for_gpa(struct kvm *kvm,
+                                   struct kvm_mmu_memory_cache *cache,
+                                   unsigned long addr)
+{
+        return kvm_mips_walk_pgd(kvm->arch.gpa_mm.pgd, cache, addr);
+}
+
+/*
+ * kvm_mips_flush_gpa_{pte,pmd,pud,pgd,pt}.
+ * Flush a range of guest physical address space from the VM's GPA page tables.
+ */
+
+static bool kvm_mips_flush_gpa_pte(pte_t *pte, unsigned long start_gpa,
+                                   unsigned long end_gpa)
+{
+        int i_min = pte_index(start_gpa);
+        int i_max = pte_index(end_gpa);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i) {
+                if (!pte_present(pte[i]))
+                        continue;
+
+                set_pte(pte + i, __pte(0));
+        }
+        return safe_to_remove;
+}
+
+static bool kvm_mips_flush_gpa_pmd(pmd_t *pmd, unsigned long start_gpa,
+                                   unsigned long end_gpa)
+{
+        pte_t *pte;
+        unsigned long end = ~0ul;
+        int i_min = pmd_index(start_gpa);
+        int i_max = pmd_index(end_gpa);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
+                if (!pmd_present(pmd[i]))
+                        continue;
+
+                pte = pte_offset_kernel(pmd + i, 0);
+                if (i == i_max)
+                        end = end_gpa;
+
+                if (kvm_mips_flush_gpa_pte(pte, start_gpa, end)) {
+                        pmd_clear(pmd + i);
+                        pte_free_kernel(NULL, pte);
+                } else {
+                        safe_to_remove = false;
+                }
+        }
+        return safe_to_remove;
+}
+
+static bool kvm_mips_flush_gpa_pud(pud_t *pud, unsigned long start_gpa,
+                                   unsigned long end_gpa)
+{
+        pmd_t *pmd;
+        unsigned long end = ~0ul;
+        int i_min = pud_index(start_gpa);
+        int i_max = pud_index(end_gpa);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
+                if (!pud_present(pud[i]))
+                        continue;
+
+                pmd = pmd_offset(pud + i, 0);
+                if (i == i_max)
+                        end = end_gpa;
+
+                if (kvm_mips_flush_gpa_pmd(pmd, start_gpa, end)) {
+                        pud_clear(pud + i);
+                        pmd_free(NULL, pmd);
+                } else {
+                        safe_to_remove = false;
+                }
+        }
+        return safe_to_remove;
+}
+
+static bool kvm_mips_flush_gpa_pgd(pgd_t *pgd, unsigned long start_gpa,
+                                   unsigned long end_gpa)
+{
+        p4d_t *p4d;
+        pud_t *pud;
+        unsigned long end = ~0ul;
+        int i_min = pgd_index(start_gpa);
+        int i_max = pgd_index(end_gpa);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
+                if (!pgd_present(pgd[i]))
+                        continue;
+
+                p4d = p4d_offset(pgd, 0);
+                pud = pud_offset(p4d + i, 0);
+                if (i == i_max)
+                        end = end_gpa;
+
+                if (kvm_mips_flush_gpa_pud(pud, start_gpa, end)) {
+                        pgd_clear(pgd + i);
+                        pud_free(NULL, pud);
+                } else {
+                        safe_to_remove = false;
+                }
+        }
+        return safe_to_remove;
+}
+
+/**
+ * kvm_mips_flush_gpa_pt() - Flush a range of guest physical addresses.
+ * @kvm:        KVM pointer.
+ * @start_gfn:  Guest frame number of first page in GPA range to flush.
+ * @end_gfn:    Guest frame number of last page in GPA range to flush.
+ *
+ * Flushes a range of GPA mappings from the GPA page tables.
+ *
+ * The caller must hold the @kvm->mmu_lock spinlock.
+ *
+ * Returns:     Whether its safe to remove the top level page directory because
+ *              all lower levels have been removed.
+ */
+bool kvm_mips_flush_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
+{
+        return kvm_mips_flush_gpa_pgd(kvm->arch.gpa_mm.pgd,
+                                      start_gfn << PAGE_SHIFT,
+                                      end_gfn << PAGE_SHIFT);
+}
+
+#define BUILD_PTE_RANGE_OP(name, op)                                    \
+static int kvm_mips_##name##_pte(pte_t *pte, unsigned long start,       \
+                                 unsigned long end)                     \
+{                                                                       \
+        int ret = 0;                                                    \
+        int i_min = pte_index(start);                           \
+        int i_max = pte_index(end);                                     \
+        int i;                                                          \
+        pte_t old, new;                                                 \
+                                                                        \
+        for (i = i_min; i <= i_max; ++i) {                              \
+                if (!pte_present(pte[i]))                               \
+                        continue;                                       \
+                                                                        \
+                old = pte[i];                                           \
+                new = op(old);                                          \
+                if (pte_val(new) == pte_val(old))                       \
+                        continue;                                       \
+                set_pte(pte + i, new);                                  \
+                ret = 1;                                                \
+        }                                                               \
+        return ret;                                                     \
+}                                                                       \
+                                                                        \
+/* returns true if anything was done */                                 \
+static int kvm_mips_##name##_pmd(pmd_t *pmd, unsigned long start,       \
+                                 unsigned long end)                     \
+{                                                                       \
+        int ret = 0;                                                    \
+        pte_t *pte;                                                     \
+        unsigned long cur_end = ~0ul;                                   \
+        int i_min = pmd_index(start);                           \
+        int i_max = pmd_index(end);                                     \
+        int i;                                                          \
+                                                                        \
+        for (i = i_min; i <= i_max; ++i, start = 0) {                   \
+                if (!pmd_present(pmd[i]))                               \
+                        continue;                                       \
+                                                                        \
+                pte = pte_offset_kernel(pmd + i, 0);                            \
+                if (i == i_max)                                         \
+                        cur_end = end;                                  \
+                                                                        \
+                ret |= kvm_mips_##name##_pte(pte, start, cur_end);      \
+        }                                                               \
+        return ret;                                                     \
+}                                                                       \
+                                                                        \
+static int kvm_mips_##name##_pud(pud_t *pud, unsigned long start,       \
+                                 unsigned long end)                     \
+{                                                                       \
+        int ret = 0;                                                    \
+        pmd_t *pmd;                                                     \
+        unsigned long cur_end = ~0ul;                                   \
+        int i_min = pud_index(start);                           \
+        int i_max = pud_index(end);                                     \
+        int i;                                                          \
+                                                                        \
+        for (i = i_min; i <= i_max; ++i, start = 0) {                   \
+                if (!pud_present(pud[i]))                               \
+                        continue;                                       \
+                                                                        \
+                pmd = pmd_offset(pud + i, 0);                           \
+                if (i == i_max)                                         \
+                        cur_end = end;                                  \
+                                                                        \
+                ret |= kvm_mips_##name##_pmd(pmd, start, cur_end);      \
+        }                                                               \
+        return ret;                                                     \
+}                                                                       \
+                                                                        \
+static int kvm_mips_##name##_pgd(pgd_t *pgd, unsigned long start,       \
+                                 unsigned long end)                     \
+{                                                                       \
+        int ret = 0;                                                    \
+        p4d_t *p4d;                                                     \
+        pud_t *pud;                                                     \
+        unsigned long cur_end = ~0ul;                                   \
+        int i_min = pgd_index(start);                                   \
+        int i_max = pgd_index(end);                                     \
+        int i;                                                          \
+                                                                        \
+        for (i = i_min; i <= i_max; ++i, start = 0) {                   \
+                if (!pgd_present(pgd[i]))                               \
+                        continue;                                       \
+                                                                        \
+                p4d = p4d_offset(pgd, 0);                               \
+                pud = pud_offset(p4d + i, 0);                           \
+                if (i == i_max)                                         \
+                        cur_end = end;                                  \
+                                                                        \
+                ret |= kvm_mips_##name##_pud(pud, start, cur_end);      \
+        }                                                               \
+        return ret;                                                     \
+}
+
+/*
+ * kvm_mips_mkclean_gpa_pt.
+ * Mark a range of guest physical address space clean (writes fault) in the VM's
+ * GPA page table to allow dirty page tracking.
+ */
+
+BUILD_PTE_RANGE_OP(mkclean, pte_mkclean)
+
+/**
+ * kvm_mips_mkclean_gpa_pt() - Make a range of guest physical addresses clean.
+ * @kvm:        KVM pointer.
+ * @start_gfn:  Guest frame number of first page in GPA range to flush.
+ * @end_gfn:    Guest frame number of last page in GPA range to flush.
+ *
+ * Make a range of GPA mappings clean so that guest writes will fault and
+ * trigger dirty page logging.
+ *
+ * The caller must hold the @kvm->mmu_lock spinlock.
+ *
+ * Returns:     Whether any GPA mappings were modified, which would require
+ *              derived mappings (GVA page tables & TLB enties) to be
+ *              invalidated.
+ */
+int kvm_mips_mkclean_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
+{
+        return kvm_mips_mkclean_pgd(kvm->arch.gpa_mm.pgd,
+                                    start_gfn << PAGE_SHIFT,
+                                    end_gfn << PAGE_SHIFT);
+}
+
+/**
+ * kvm_arch_mmu_enable_log_dirty_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.
+ */
+void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+                struct kvm_memory_slot *slot,
+                gfn_t gfn_offset, unsigned long mask)
+{
+        gfn_t base_gfn = slot->base_gfn + gfn_offset;
+        gfn_t start = base_gfn +  __ffs(mask);
+        gfn_t end = base_gfn + __fls(mask);
+
+        kvm_mips_mkclean_gpa_pt(kvm, start, end);
+}
+
+/*
+ * kvm_mips_mkold_gpa_pt.
+ * Mark a range of guest physical address space old (all accesses fault) in the
+ * VM's GPA page table to allow detection of commonly used pages.
+ */
+
+BUILD_PTE_RANGE_OP(mkold, pte_mkold)
+
+static int kvm_mips_mkold_gpa_pt(struct kvm *kvm, gfn_t start_gfn,
+                                 gfn_t end_gfn)
+{
+        return kvm_mips_mkold_pgd(kvm->arch.gpa_mm.pgd,
+                                  start_gfn << PAGE_SHIFT,
+                                  end_gfn << PAGE_SHIFT);
+}
+
+static int handle_hva_to_gpa(struct kvm *kvm,
+                             unsigned long start,
+                             unsigned long end,
+                             int (*handler)(struct kvm *kvm, gfn_t gfn,
+                                            gpa_t gfn_end,
+                                            struct kvm_memory_slot *memslot,
+                                            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 gfn, gfn_end;
+
+                hva_start = max(start, memslot->userspace_addr);
+                hva_end = min(end, memslot->userspace_addr +
+                                        (memslot->npages << PAGE_SHIFT));
+                if (hva_start >= hva_end)
+                        continue;
+
+                /*
+                 * {gfn(page) | page intersects with [hva_start, hva_end)} =
+                 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
+                 */
+                gfn = hva_to_gfn_memslot(hva_start, memslot);
+                gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
+
+                ret |= handler(kvm, gfn, gfn_end, memslot, data);
+        }
+
+        return ret;
+}
+
+
+static int kvm_unmap_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
+                                 struct kvm_memory_slot *memslot, void *data)
+{
+        kvm_mips_flush_gpa_pt(kvm, gfn, gfn_end);
+        return 1;
+}
+
+int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,
+                        unsigned flags)
+{
+        handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL);
+
+        kvm_mips_callbacks->flush_shadow_all(kvm);
+        return 0;
+}
+
+static int kvm_set_spte_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
+                                struct kvm_memory_slot *memslot, void *data)
+{
+        gpa_t gpa = gfn << PAGE_SHIFT;
+        pte_t hva_pte = *(pte_t *)data;
+        pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
+        pte_t old_pte;
+
+        if (!gpa_pte)
+                return 0;
+
+        /* Mapping may need adjusting depending on memslot flags */
+        old_pte = *gpa_pte;
+        if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES && !pte_dirty(old_pte))
+                hva_pte = pte_mkclean(hva_pte);
+        else if (memslot->flags & KVM_MEM_READONLY)
+                hva_pte = pte_wrprotect(hva_pte);
+
+        set_pte(gpa_pte, hva_pte);
+
+        /* Replacing an absent or old page doesn't need flushes */
+        if (!pte_present(old_pte) || !pte_young(old_pte))
+                return 0;
+
+        /* Pages swapped, aged, moved, or cleaned require flushes */
+        return !pte_present(hva_pte) ||
+               !pte_young(hva_pte) ||
+               pte_pfn(old_pte) != pte_pfn(hva_pte) ||
+               (pte_dirty(old_pte) && !pte_dirty(hva_pte));
+}
+
+int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
+{
+        unsigned long end = hva + PAGE_SIZE;
+        int ret;
+
+        ret = handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &pte);
+        if (ret)
+                kvm_mips_callbacks->flush_shadow_all(kvm);
+        return 0;
+}
+
+static int kvm_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
+                               struct kvm_memory_slot *memslot, void *data)
+{
+        return kvm_mips_mkold_gpa_pt(kvm, gfn, gfn_end);
+}
+
+static int kvm_test_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
+                                    struct kvm_memory_slot *memslot, void *data)
+{
+        gpa_t gpa = gfn << PAGE_SHIFT;
+        pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
+
+        if (!gpa_pte)
+                return 0;
+        return pte_young(*gpa_pte);
+}
+
+int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long 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)
+{
+        return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL);
+}
+
+/**
+ * _kvm_mips_map_page_fast() - Fast path GPA fault handler.
+ * @vcpu:               VCPU pointer.
+ * @gpa:                Guest physical address of fault.
+ * @write_fault:        Whether the fault was due to a write.
+ * @out_entry:          New PTE for @gpa (written on success unless NULL).
+ * @out_buddy:          New PTE for @gpa's buddy (written on success unless
+ *                      NULL).
+ *
+ * Perform fast path GPA fault handling, doing all that can be done without
+ * calling into KVM. This handles marking old pages young (for idle page
+ * tracking), and dirtying of clean pages (for dirty page logging).
+ *
+ * Returns:     0 on success, in which case we can update derived mappings and
+ *              resume guest execution.
+ *              -EFAULT on failure due to absent GPA mapping or write to
+ *              read-only page, in which case KVM must be consulted.
+ */
+static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa,
+                                   bool write_fault,
+                                   pte_t *out_entry, pte_t *out_buddy)
+{
+        struct kvm *kvm = vcpu->kvm;
+        gfn_t gfn = gpa >> PAGE_SHIFT;
+        pte_t *ptep;
+        kvm_pfn_t pfn = 0;      /* silence bogus GCC warning */
+        bool pfn_valid = false;
+        int ret = 0;
+
+        spin_lock(&kvm->mmu_lock);
+
+        /* Fast path - just check GPA page table for an existing entry */
+        ptep = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
+        if (!ptep || !pte_present(*ptep)) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        /* Track access to pages marked old */
+        if (!pte_young(*ptep)) {
+                set_pte(ptep, pte_mkyoung(*ptep));
+                pfn = pte_pfn(*ptep);
+                pfn_valid = true;
+                /* call kvm_set_pfn_accessed() after unlock */
+        }
+        if (write_fault && !pte_dirty(*ptep)) {
+                if (!pte_write(*ptep)) {
+                        ret = -EFAULT;
+                        goto out;
+                }
+
+                /* Track dirtying of writeable pages */
+                set_pte(ptep, pte_mkdirty(*ptep));
+                pfn = pte_pfn(*ptep);
+                mark_page_dirty(kvm, gfn);
+                kvm_set_pfn_dirty(pfn);
+        }
+
+        if (out_entry)
+                *out_entry = *ptep;
+        if (out_buddy)
+                *out_buddy = *ptep_buddy(ptep);
+
+out:
+        spin_unlock(&kvm->mmu_lock);
+        if (pfn_valid)
+                kvm_set_pfn_accessed(pfn);
+        return ret;
+}
+
+/**
+ * kvm_mips_map_page() - Map a guest physical page.
+ * @vcpu:               VCPU pointer.
+ * @gpa:                Guest physical address of fault.
+ * @write_fault:        Whether the fault was due to a write.
+ * @out_entry:          New PTE for @gpa (written on success unless NULL).
+ * @out_buddy:          New PTE for @gpa's buddy (written on success unless
+ *                      NULL).
+ *
+ * Handle GPA faults by creating a new GPA mapping (or updating an existing
+ * one).
+ *
+ * This takes care of marking pages young or dirty (idle/dirty page tracking),
+ * asking KVM for the corresponding PFN, and creating a mapping in the GPA page
+ * tables. Derived mappings (GVA page tables and TLBs) must be handled by the
+ * caller.
+ *
+ * Returns:     0 on success, in which case the caller may use the @out_entry
+ *              and @out_buddy PTEs to update derived mappings and resume guest
+ *              execution.
+ *              -EFAULT if there is no memory region at @gpa or a write was
+ *              attempted to a read-only memory region. This is usually handled
+ *              as an MMIO access.
+ */
+static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa,
+                             bool write_fault,
+                             pte_t *out_entry, pte_t *out_buddy)
+{
+        struct kvm *kvm = vcpu->kvm;
+        struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
+        gfn_t gfn = gpa >> PAGE_SHIFT;
+        int srcu_idx, err;
+        kvm_pfn_t pfn;
+        pte_t *ptep, entry, old_pte;
+        bool writeable;
+        unsigned long prot_bits;
+        unsigned long mmu_seq;
+
+        /* Try the fast path to handle old / clean pages */
+        srcu_idx = srcu_read_lock(&kvm->srcu);
+        err = _kvm_mips_map_page_fast(vcpu, gpa, write_fault, out_entry,
+                                      out_buddy);
+        if (!err)
+                goto out;
+
+        /* We need a minimum of cached pages ready for page table creation */
+        err = kvm_mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES);
+        if (err)
+                goto out;
+
+retry:
+        /*
+         * Used to check for invalidations in progress, of the pfn that is
+         * returned by pfn_to_pfn_prot below.
+         */
+        mmu_seq = kvm->mmu_notifier_seq;
+        /*
+         * Ensure the read of mmu_notifier_seq isn't reordered with PTE reads in
+         * gfn_to_pfn_prot() (which calls get_user_pages()), so that we don't
+         * risk the page we get a reference to getting unmapped before we have a
+         * chance to grab the mmu_lock without mmu_notifier_retry() noticing.
+         *
+         * This smp_rmb() pairs with the effective smp_wmb() of the combination
+         * of the pte_unmap_unlock() after the PTE is zapped, and the
+         * spin_lock() in kvm_mmu_notifier_invalidate_<page|range_end>() before
+         * mmu_notifier_seq is incremented.
+         */
+        smp_rmb();
+
+        /* Slow path - ask KVM core whether we can access this GPA */
+        pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writeable);
+        if (is_error_noslot_pfn(pfn)) {
+                err = -EFAULT;
+                goto out;
+        }
+
+        spin_lock(&kvm->mmu_lock);
+        /* Check if an invalidation has taken place since we got pfn */
+        if (mmu_notifier_retry(kvm, mmu_seq)) {
+                /*
+                 * This can happen when mappings are changed asynchronously, but
+                 * also synchronously if a COW is triggered by
+                 * gfn_to_pfn_prot().
+                 */
+                spin_unlock(&kvm->mmu_lock);
+                kvm_release_pfn_clean(pfn);
+                goto retry;
+        }
+
+        /* Ensure page tables are allocated */
+        ptep = kvm_mips_pte_for_gpa(kvm, memcache, gpa);
+
+        /* Set up the PTE */
+        prot_bits = _PAGE_PRESENT | __READABLE | _page_cachable_default;
+        if (writeable) {
+                prot_bits |= _PAGE_WRITE;
+                if (write_fault) {
+                        prot_bits |= __WRITEABLE;
+                        mark_page_dirty(kvm, gfn);
+                        kvm_set_pfn_dirty(pfn);
+                }
+        }
+        entry = pfn_pte(pfn, __pgprot(prot_bits));
+
+        /* Write the PTE */
+        old_pte = *ptep;
+        set_pte(ptep, entry);
+
+        err = 0;
+        if (out_entry)
+                *out_entry = *ptep;
+        if (out_buddy)
+                *out_buddy = *ptep_buddy(ptep);
+
+        spin_unlock(&kvm->mmu_lock);
+        kvm_release_pfn_clean(pfn);
+        kvm_set_pfn_accessed(pfn);
+out:
+        srcu_read_unlock(&kvm->srcu, srcu_idx);
+        return err;
+}
+
+static pte_t *kvm_trap_emul_pte_for_gva(struct kvm_vcpu *vcpu,
+                                        unsigned long addr)
+{
+        struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
+        pgd_t *pgdp;
+        int ret;
+
+        /* We need a minimum of cached pages ready for page table creation */
+        ret = kvm_mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES);
+        if (ret)
+                return NULL;
+
+        if (KVM_GUEST_KERNEL_MODE(vcpu))
+                pgdp = vcpu->arch.guest_kernel_mm.pgd;
+        else
+                pgdp = vcpu->arch.guest_user_mm.pgd;
+
+        return kvm_mips_walk_pgd(pgdp, memcache, addr);
+}
+
+void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
+                                  bool user)
+{
+        pgd_t *pgdp;
+        pte_t *ptep;
+
+        addr &= PAGE_MASK << 1;
+
+        pgdp = vcpu->arch.guest_kernel_mm.pgd;
+        ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
+        if (ptep) {
+                ptep[0] = pfn_pte(0, __pgprot(0));
+                ptep[1] = pfn_pte(0, __pgprot(0));
+        }
+
+        if (user) {
+                pgdp = vcpu->arch.guest_user_mm.pgd;
+                ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
+                if (ptep) {
+                        ptep[0] = pfn_pte(0, __pgprot(0));
+                        ptep[1] = pfn_pte(0, __pgprot(0));
+                }
+        }
+}
+
+/*
+ * kvm_mips_flush_gva_{pte,pmd,pud,pgd,pt}.
+ * Flush a range of guest physical address space from the VM's GPA page tables.
+ */
+
+static bool kvm_mips_flush_gva_pte(pte_t *pte, unsigned long start_gva,
+                                   unsigned long end_gva)
+{
+        int i_min = pte_index(start_gva);
+        int i_max = pte_index(end_gva);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
+        int i;
+
+        /*
+         * There's no freeing to do, so there's no point clearing individual
+         * entries unless only part of the last level page table needs flushing.
+         */
+        if (safe_to_remove)
+                return true;
+
+        for (i = i_min; i <= i_max; ++i) {
+                if (!pte_present(pte[i]))
+                        continue;
+
+                set_pte(pte + i, __pte(0));
+        }
+        return false;
+}
+
+static bool kvm_mips_flush_gva_pmd(pmd_t *pmd, unsigned long start_gva,
+                                   unsigned long end_gva)
+{
+        pte_t *pte;
+        unsigned long end = ~0ul;
+        int i_min = pmd_index(start_gva);
+        int i_max = pmd_index(end_gva);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i, start_gva = 0) {
+                if (!pmd_present(pmd[i]))
+                        continue;
+
+                pte = pte_offset_kernel(pmd + i, 0);
+                if (i == i_max)
+                        end = end_gva;
+
+                if (kvm_mips_flush_gva_pte(pte, start_gva, end)) {
+                        pmd_clear(pmd + i);
+                        pte_free_kernel(NULL, pte);
+                } else {
+                        safe_to_remove = false;
+                }
+        }
+        return safe_to_remove;
+}
+
+static bool kvm_mips_flush_gva_pud(pud_t *pud, unsigned long start_gva,
+                                   unsigned long end_gva)
+{
+        pmd_t *pmd;
+        unsigned long end = ~0ul;
+        int i_min = pud_index(start_gva);
+        int i_max = pud_index(end_gva);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i, start_gva = 0) {
+                if (!pud_present(pud[i]))
+                        continue;
+
+                pmd = pmd_offset(pud + i, 0);
+                if (i == i_max)
+                        end = end_gva;
+
+                if (kvm_mips_flush_gva_pmd(pmd, start_gva, end)) {
+                        pud_clear(pud + i);
+                        pmd_free(NULL, pmd);
+                } else {
+                        safe_to_remove = false;
+                }
+        }
+        return safe_to_remove;
+}
+
+static bool kvm_mips_flush_gva_pgd(pgd_t *pgd, unsigned long start_gva,
+                                   unsigned long end_gva)
+{
+        p4d_t *p4d;
+        pud_t *pud;
+        unsigned long end = ~0ul;
+        int i_min = pgd_index(start_gva);
+        int i_max = pgd_index(end_gva);
+        bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
+        int i;
+
+        for (i = i_min; i <= i_max; ++i, start_gva = 0) {
+                if (!pgd_present(pgd[i]))
+                        continue;
+
+                p4d = p4d_offset(pgd, 0);
+                pud = pud_offset(p4d + i, 0);
+                if (i == i_max)
+                        end = end_gva;
+
+                if (kvm_mips_flush_gva_pud(pud, start_gva, end)) {
+                        pgd_clear(pgd + i);
+                        pud_free(NULL, pud);
+                } else {
+                        safe_to_remove = false;
+                }
+        }
+        return safe_to_remove;
+}
+
+void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags)
+{
+        if (flags & KMF_GPA) {
+                /* all of guest virtual address space could be affected */
+                if (flags & KMF_KERN)
+                        /* useg, kseg0, seg2/3 */
+                        kvm_mips_flush_gva_pgd(pgd, 0, 0x7fffffff);
+                else
+                        /* useg */
+                        kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
+        } else {
+                /* useg */
+                kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
+
+                /* kseg2/3 */
+                if (flags & KMF_KERN)
+                        kvm_mips_flush_gva_pgd(pgd, 0x60000000, 0x7fffffff);
+        }
+}
+
+static pte_t kvm_mips_gpa_pte_to_gva_unmapped(pte_t pte)
+{
+        /*
+         * Don't leak writeable but clean entries from GPA page tables. We don't
+         * want the normal Linux tlbmod handler to handle dirtying when KVM
+         * accesses guest memory.
+         */
+        if (!pte_dirty(pte))
+                pte = pte_wrprotect(pte);
+
+        return pte;
+}
+
+static pte_t kvm_mips_gpa_pte_to_gva_mapped(pte_t pte, long entrylo)
+{
+        /* Guest EntryLo overrides host EntryLo */
+        if (!(entrylo & ENTRYLO_D))
+                pte = pte_mkclean(pte);
+
+        return kvm_mips_gpa_pte_to_gva_unmapped(pte);
+}
+
+#ifdef CONFIG_KVM_MIPS_VZ
+int kvm_mips_handle_vz_root_tlb_fault(unsigned long badvaddr,
+                                      struct kvm_vcpu *vcpu,
+                                      bool write_fault)
+{
+        int ret;
+
+        ret = kvm_mips_map_page(vcpu, badvaddr, write_fault, NULL, NULL);
+        if (ret)
+                return ret;
+
+        /* Invalidate this entry in the TLB */
+        return kvm_vz_host_tlb_inv(vcpu, badvaddr);
+}
+#endif
+
+/* XXXKYMA: Must be called with interrupts disabled */
+int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
+                                    struct kvm_vcpu *vcpu,
+                                    bool write_fault)
+{
+        unsigned long gpa;
+        pte_t pte_gpa[2], *ptep_gva;
+        int idx;
+
+        if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) {
+                kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr);
+                kvm_mips_dump_host_tlbs();
+                return -1;
+        }
+
+        /* Get the GPA page table entry */
+        gpa = KVM_GUEST_CPHYSADDR(badvaddr);
+        idx = (badvaddr >> PAGE_SHIFT) & 1;
+        if (kvm_mips_map_page(vcpu, gpa, write_fault, &pte_gpa[idx],
+                              &pte_gpa[!idx]) < 0)
+                return -1;
+
+        /* Get the GVA page table entry */
+        ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, badvaddr & ~PAGE_SIZE);
+        if (!ptep_gva) {
+                kvm_err("No ptep for gva %lx\n", badvaddr);
+                return -1;
+        }
+
+        /* Copy a pair of entries from GPA page table to GVA page table */
+        ptep_gva[0] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[0]);
+        ptep_gva[1] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[1]);
+
+        /* Invalidate this entry in the TLB, guest kernel ASID only */
+        kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
+        return 0;
+}
+
+int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
+                                         struct kvm_mips_tlb *tlb,
+                                         unsigned long gva,
+                                         bool write_fault)
+{
+        struct kvm *kvm = vcpu->kvm;
+        long tlb_lo[2];
+        pte_t pte_gpa[2], *ptep_buddy, *ptep_gva;
+        unsigned int idx = TLB_LO_IDX(*tlb, gva);
+        bool kernel = KVM_GUEST_KERNEL_MODE(vcpu);
+
+        tlb_lo[0] = tlb->tlb_lo[0];
+        tlb_lo[1] = tlb->tlb_lo[1];
+
+        /*
+         * The commpage address must not be mapped to anything else if the guest
+         * TLB contains entries nearby, or commpage accesses will break.
+         */
+        if (!((gva ^ KVM_GUEST_COMMPAGE_ADDR) & VPN2_MASK & (PAGE_MASK << 1)))
+                tlb_lo[TLB_LO_IDX(*tlb, KVM_GUEST_COMMPAGE_ADDR)] = 0;
+
+        /* Get the GPA page table entry */
+        if (kvm_mips_map_page(vcpu, mips3_tlbpfn_to_paddr(tlb_lo[idx]),
+                              write_fault, &pte_gpa[idx], NULL) < 0)
+                return -1;
+
+        /* And its GVA buddy's GPA page table entry if it also exists */
+        pte_gpa[!idx] = pfn_pte(0, __pgprot(0));
+        if (tlb_lo[!idx] & ENTRYLO_V) {
+                spin_lock(&kvm->mmu_lock);
+                ptep_buddy = kvm_mips_pte_for_gpa(kvm, NULL,
+                                        mips3_tlbpfn_to_paddr(tlb_lo[!idx]));
+                if (ptep_buddy)
+                        pte_gpa[!idx] = *ptep_buddy;
+                spin_unlock(&kvm->mmu_lock);
+        }
+
+        /* Get the GVA page table entry pair */
+        ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, gva & ~PAGE_SIZE);
+        if (!ptep_gva) {
+                kvm_err("No ptep for gva %lx\n", gva);
+                return -1;
+        }
+
+        /* Copy a pair of entries from GPA page table to GVA page table */
+        ptep_gva[0] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[0], tlb_lo[0]);
+        ptep_gva[1] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[1], tlb_lo[1]);
+
+        /* Invalidate this entry in the TLB, current guest mode ASID only */
+        kvm_mips_host_tlb_inv(vcpu, gva, !kernel, kernel);
+
+        kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
+                  tlb->tlb_lo[0], tlb->tlb_lo[1]);
+
+        return 0;
+}
+
+int kvm_mips_handle_commpage_tlb_fault(unsigned long badvaddr,
+                                       struct kvm_vcpu *vcpu)
+{
+        kvm_pfn_t pfn;
+        pte_t *ptep;
+
+        ptep = kvm_trap_emul_pte_for_gva(vcpu, badvaddr);
+        if (!ptep) {
+                kvm_err("No ptep for commpage %lx\n", badvaddr);
+                return -1;
+        }
+
+        pfn = PFN_DOWN(virt_to_phys(vcpu->arch.kseg0_commpage));
+        /* Also set valid and dirty, so refill handler doesn't have to */
+        *ptep = pte_mkyoung(pte_mkdirty(pfn_pte(pfn, PAGE_SHARED)));
+
+        /* Invalidate this entry in the TLB, guest kernel ASID only */
+        kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
+        return 0;
+}
+
+/**
+ * kvm_mips_migrate_count() - Migrate timer.
+ * @vcpu:       Virtual CPU.
+ *
+ * Migrate CP0_Count hrtimer to the current CPU by cancelling and restarting it
+ * if it was running prior to being cancelled.
+ *
+ * Must be called when the VCPU is migrated to a different CPU to ensure that
+ * timer expiry during guest execution interrupts the guest and causes the
+ * interrupt to be delivered in a timely manner.
+ */
+static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu)
+{
+        if (hrtimer_cancel(&vcpu->arch.comparecount_timer))
+                hrtimer_restart(&vcpu->arch.comparecount_timer);
+}
+
+/* Restore ASID once we are scheduled back after preemption */
+void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+        unsigned long flags;
+
+        kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu);
+
+        local_irq_save(flags);
+
+        vcpu->cpu = cpu;
+        if (vcpu->arch.last_sched_cpu != cpu) {
+                kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
+                          vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
+                /*
+                 * Migrate the timer interrupt to the current CPU so that it
+                 * always interrupts the guest and synchronously triggers a
+                 * guest timer interrupt.
+                 */
+                kvm_mips_migrate_count(vcpu);
+        }
+
+        /* restore guest state to registers */
+        kvm_mips_callbacks->vcpu_load(vcpu, cpu);
+
+        local_irq_restore(flags);
+}
+
+/* ASID can change if another task is scheduled during preemption */
+void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
+{
+        unsigned long flags;
+        int cpu;
+
+        local_irq_save(flags);
+
+        cpu = smp_processor_id();
+        vcpu->arch.last_sched_cpu = cpu;
+        vcpu->cpu = -1;
+
+        /* save guest state in registers */
+        kvm_mips_callbacks->vcpu_put(vcpu, cpu);
+
+        local_irq_restore(flags);
+}
+
+/**
+ * kvm_trap_emul_gva_fault() - Safely attempt to handle a GVA access fault.
+ * @vcpu:       Virtual CPU.
+ * @gva:        Guest virtual address to be accessed.
+ * @write:      True if write attempted (must be dirtied and made writable).
+ *
+ * Safely attempt to handle a GVA fault, mapping GVA pages if necessary, and
+ * dirtying the page if @write so that guest instructions can be modified.
+ *
+ * Returns:     KVM_MIPS_MAPPED on success.
+ *              KVM_MIPS_GVA if bad guest virtual address.
+ *              KVM_MIPS_GPA if bad guest physical address.
+ *              KVM_MIPS_TLB if guest TLB not present.
+ *              KVM_MIPS_TLBINV if guest TLB present but not valid.
+ *              KVM_MIPS_TLBMOD if guest TLB read only.
+ */
+enum kvm_mips_fault_result kvm_trap_emul_gva_fault(struct kvm_vcpu *vcpu,
+                                                   unsigned long gva,
+                                                   bool write)
+{
+        struct mips_coproc *cop0 = vcpu->arch.cop0;
+        struct kvm_mips_tlb *tlb;
+        int index;
+
+        if (KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG0) {
+                if (kvm_mips_handle_kseg0_tlb_fault(gva, vcpu, write) < 0)
+                        return KVM_MIPS_GPA;
+        } else if ((KVM_GUEST_KSEGX(gva) < KVM_GUEST_KSEG0) ||
+                   KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG23) {
+                /* Address should be in the guest TLB */
+                index = kvm_mips_guest_tlb_lookup(vcpu, (gva & VPN2_MASK) |
+                          (kvm_read_c0_guest_entryhi(cop0) & KVM_ENTRYHI_ASID));
+                if (index < 0)
+                        return KVM_MIPS_TLB;
+                tlb = &vcpu->arch.guest_tlb[index];
+
+                /* Entry should be valid, and dirty for writes */
+                if (!TLB_IS_VALID(*tlb, gva))
+                        return KVM_MIPS_TLBINV;
+                if (write && !TLB_IS_DIRTY(*tlb, gva))
+                        return KVM_MIPS_TLBMOD;
+
+                if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, gva, write))
+                        return KVM_MIPS_GPA;
+        } else {
+                return KVM_MIPS_GVA;
+        }
+
+        return KVM_MIPS_MAPPED;
+}
+
+int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
+{
+        int err;
+
+        if (WARN(IS_ENABLED(CONFIG_KVM_MIPS_VZ),
+                 "Expect BadInstr/BadInstrP registers to be used with VZ\n"))
+                return -EINVAL;
+
+retry:
+        kvm_trap_emul_gva_lockless_begin(vcpu);
+        err = get_user(*out, opc);
+        kvm_trap_emul_gva_lockless_end(vcpu);
+
+        if (unlikely(err)) {
+                /*
+                 * Try to handle the fault, maybe we just raced with a GVA
+                 * invalidation.
+                 */
+                err = kvm_trap_emul_gva_fault(vcpu, (unsigned long)opc,
+                                              false);
+                if (unlikely(err)) {
+                        kvm_err("%s: illegal address: %p\n",
+                                __func__, opc);
+                        return -EFAULT;
+                }
+
+                /* Hopefully it'll work now */
+                goto retry;
+        }
+        return 0;
+}