+
+/**
+ * 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 *pgd;
+
+ pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 0);
+ if (pgd)
+ pgd_init((void *)pgd);
+
+ return pgd;
+}
+
+/**
+ * kvm_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_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 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((void *)new_pmd);
+ 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_pte_for_gpa(struct kvm *kvm,
+ struct kvm_mmu_memory_cache *cache,
+ unsigned long addr)
+{
+ return kvm_walk_pgd(kvm->arch.gpa_mm.pgd, cache, addr);
+}
+
+/*
+ * level2_flush_{pte,pmd,pud,pgd,pt}.
+ * Flush a range of guest physical address space from the VM's GPA page tables.
+ */
+static int level2_flush_pte(pmd_t *pmd, unsigned long addr, unsigned long end)
+{
+ pte_t *pte;
+ unsigned long next, start;
+ int ret;
+
+ ret = 0;
+ start = addr;
+ pte = pte_offset_kernel(pmd, addr);
+ do {
+ next = addr + PAGE_SIZE;
+ if (!pte_present(*pte))
+ continue;
+
+ set_pte(pte, __pte(0));
+ ret = 1;
+ } while (pte++, addr = next, addr != end);
+
+ if (start + PMD_SIZE == end) {
+ pte = pte_offset_kernel(pmd, 0);
+ pmd_clear(pmd);
+ pte_free_kernel(NULL, pte);
+ }
+ return ret;
+}
+
+static int level2_flush_pmd(pud_t *pud, unsigned long addr, unsigned long end)
+{
+ pmd_t *pmd;
+ unsigned long next, start;
+ int ret;
+
+ ret = 0;
+ start = addr;
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (!pmd_present(*pmd))
+ continue;
+
+ ret |= level2_flush_pte(pmd, addr, next);
+ } while (pmd++, addr = next, addr != end);
+
+ if (start + PUD_SIZE == end) {
+ pmd = pmd_offset(pud, 0);
+ pud_clear(pud);
+ pmd_free(NULL, pmd);
+ }
+ return ret;
+}
+
+static int level2_flush_pud(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+ p4d_t *p4d;
+ pud_t *pud;
+ unsigned long next, start;
+ int ret;
+
+ ret = 0;
+ start = addr;
+ p4d = p4d_offset(pgd, addr);
+ pud = pud_offset(p4d, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (!pud_present(*pud))
+ continue;
+
+ ret |= level2_flush_pmd(pud, addr, next);
+ } while (pud++, addr = next, addr != end);
+
+ if (start + PGDIR_SIZE == end) {
+ pud = pud_offset(p4d, 0);
+ pgd_clear(pgd);
+ pud_free(NULL, pud);
+ }
+ return ret;
+}
+
+static int level2_flush_pgd(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+ unsigned long next;
+ int ret;
+
+ ret = 0;
+ if (addr > end - 1)
+ return ret;
+ pgd = pgd + pgd_index(addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (!pgd_present(*pgd))
+ continue;
+
+ ret |= level2_flush_pud(pgd, addr, next);
+ } while (pgd++, addr = next, addr != end);
+
+ return ret;
+}
+
+/**
+ * level2_flush_range() - 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.
+ */
+static bool level2_flush_range(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
+{
+ return level2_flush_pgd(kvm->arch.gpa_mm.pgd, start_gfn << PAGE_SHIFT,
+ end_gfn << PAGE_SHIFT);
+}
+
+typedef int (*level2_pte_ops)(void *pte);
+/*
+ * level2_mkclean_pte
+ * Mark a range of guest physical address space clean (writes fault) in the VM's
+ * GPA page table to allow dirty page tracking.
+ */
+static int level2_mkclean_pte(void *pte)
+{
+ pte_t val;
+
+ val = *(pte_t *)pte;
+ if (pte_dirty(val)) {
+ *(pte_t *)pte = pte_mkclean(val);
+ return 1;
+ }
+ return 0;
+}
+
+static int level2_ptw_pte(pmd_t *pmd, unsigned long addr, unsigned long end,
+ level2_pte_ops func)
+{
+ pte_t *pte;
+ unsigned long next;
+ int ret;
+
+ ret = 0;
+ pte = pte_offset_kernel(pmd, addr);
+ do {
+ next = addr + PAGE_SIZE;
+ if (!pte_present(*pte))
+ continue;
+
+ ret |= func(pte);
+ } while (pte++, addr = next, addr != end);
+
+ return ret;
+}
+
+static int level2_ptw_pmd(pud_t *pud, unsigned long addr, unsigned long end,
+ level2_pte_ops func)
+{
+ pmd_t *pmd;
+ unsigned long next;
+ int ret;
+
+ ret = 0;
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (!pmd_present(*pmd))
+ continue;
+
+ ret |= level2_ptw_pte(pmd, addr, next, func);
+ } while (pmd++, addr = next, addr != end);
+
+ return ret;
+}
+
+static int level2_ptw_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
+ level2_pte_ops func)
+{
+ p4d_t *p4d;
+ pud_t *pud;
+ unsigned long next;
+ int ret;
+
+ ret = 0;
+ p4d = p4d_offset(pgd, addr);
+ pud = pud_offset(p4d, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (!pud_present(*pud))
+ continue;
+
+ ret |= level2_ptw_pmd(pud, addr, next, func);
+ } while (pud++, addr = next, addr != end);
+
+ return ret;
+}
+
+static int level2_ptw_pgd(pgd_t *pgd, unsigned long addr, unsigned long end,
+ level2_pte_ops func)
+{
+ unsigned long next;
+ int ret;
+
+ ret = 0;
+ if (addr > end - 1)
+ return ret;
+ pgd = pgd + pgd_index(addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (!pgd_present(*pgd))
+ continue;
+
+ ret |= level2_ptw_pud(pgd, addr, next, func);
+ } while (pgd++, addr = next, addr != end);
+
+ return ret;
+}
+
+/*
+ * kvm_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.
+ */
+static int kvm_mkclean_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
+{
+ return level2_ptw_pgd(kvm->arch.gpa_mm.pgd, start_gfn << PAGE_SHIFT,
+ end_gfn << PAGE_SHIFT, level2_mkclean_pte);
+}
+
+/*
+ * 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) + 1;
+
+ kvm_mkclean_gpa_pt(kvm, start, end);
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+ struct kvm_memory_slot *old,
+ const struct kvm_memory_slot *new,
+ enum kvm_mr_change change)
+{
+ int needs_flush;
+
+ /*
+ * If dirty page logging is enabled, write protect all pages in the slot
+ * ready for dirty logging.
+ *
+ * There is no need to do this in any of the following cases:
+ * CREATE: No dirty mappings will already exist.
+ * MOVE/DELETE: The old mappings will already have been cleaned up by
+ * kvm_arch_flush_shadow_memslot()
+ */
+ if (change == KVM_MR_FLAGS_ONLY &&
+ (!(old->flags & KVM_MEM_LOG_DIRTY_PAGES) &&
+ new->flags & KVM_MEM_LOG_DIRTY_PAGES)) {
+ spin_lock(&kvm->mmu_lock);
+ /* Write protect GPA page table entries */
+ needs_flush = kvm_mkclean_gpa_pt(kvm, new->base_gfn,
+ new->base_gfn + new->npages);
+ if (needs_flush)
+ kvm_flush_remote_tlbs(kvm);
+ spin_unlock(&kvm->mmu_lock);
+ }
+}
+
+void kvm_arch_flush_shadow_all(struct kvm *kvm)
+{
+ /* Flush whole GPA */
+ level2_flush_range(kvm, 0, kvm->arch.gpa_size >> PAGE_SHIFT);
+ /* Flush vpid for each vCPU individually */
+ kvm_flush_remote_tlbs(kvm);
+}
+
+void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
+ struct kvm_memory_slot *slot)
+{
+ int ret;
+
+ /*
+ * The slot has been made invalid (ready for moving or deletion), so we
+ * need to ensure that it can no longer be accessed by any guest vCPUs.
+ */
+ spin_lock(&kvm->mmu_lock);
+ /* Flush slot from GPA */
+ ret = level2_flush_range(kvm, slot->base_gfn,
+ slot->base_gfn + slot->npages);
+ /* Let implementation do the rest */
+ if (ret)
+ kvm_flush_remote_tlbs(kvm);
+ spin_unlock(&kvm->mmu_lock);
+}
+
+void _kvm_destroy_mm(struct kvm *kvm)
+{
+ /* It should always be safe to remove after flushing the whole range */
+ level2_flush_range(kvm, 0, kvm->arch.gpa_size >> PAGE_SHIFT);
+ pgd_free(NULL, kvm->arch.gpa_mm.pgd);
+ kvm->arch.gpa_mm.pgd = NULL;
+}
+
+/*
+ * 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.
+ */
+static int level2_mkold_pte(void *pte)
+{
+ pte_t val;
+
+ val = *(pte_t *)pte;
+ if (pte_young(val)) {
+ *(pte_t *)pte = pte_mkold(val);
+ return 1;
+ }
+ return 0;
+}
+
+bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+ return level2_flush_range(kvm, range->start, range->end);
+}
+
+bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+ gpa_t gpa = range->start << PAGE_SHIFT;
+ pte_t hva_pte = range->pte;
+ pte_t *ptep = kvm_pte_for_gpa(kvm, NULL, gpa);
+ pte_t old_pte;
+
+ if (!ptep)
+ return false;
+
+ /* Mapping may need adjusting depending on memslot flags */
+ old_pte = *ptep;
+ if (range->slot->flags & KVM_MEM_LOG_DIRTY_PAGES && !pte_dirty(old_pte))
+ hva_pte = pte_mkclean(hva_pte);
+ else if (range->slot->flags & KVM_MEM_READONLY)
+ hva_pte = pte_wrprotect(hva_pte);
+
+ set_pte(ptep, hva_pte);
+
+ /* Replacing an absent or old page doesn't need flushes */
+ if (!pte_present(old_pte) || !pte_young(old_pte))
+ return false;
+
+ /* 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));
+}
+
+bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+ return level2_ptw_pgd(kvm->arch.gpa_mm.pgd, range->start << PAGE_SHIFT,
+ range->end << PAGE_SHIFT, level2_mkold_pte);
+}
+
+bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+ gpa_t gpa = range->start << PAGE_SHIFT;
+ pte_t *ptep = kvm_pte_for_gpa(kvm, NULL, gpa);
+
+ if (ptep && pte_present(*ptep) && pte_young(*ptep))
+ return true;
+
+ return false;
+}
+
+/**
+ * kvm_map_page_fast() - Fast path GPA fault handler.
+ * @vcpu: vCPU pointer.
+ * @gpa: Guest physical address of fault.
+ * @write: Whether the fault was due to a write.
+ *
+ * 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_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa,
+ bool write)
+{
+ struct kvm *kvm = vcpu->kvm;
+ gfn_t gfn = gpa >> PAGE_SHIFT;
+ pte_t *ptep;
+ kvm_pfn_t pfn = 0;
+ 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_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 && !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);
+ }
+
+out:
+ spin_unlock(&kvm->mmu_lock);
+ if (pfn_valid)
+ kvm_set_pfn_accessed(pfn);
+ return ret;
+}
+
+/**
+ * kvm_map_page() - Map a guest physical page.
+ * @vcpu: vCPU pointer.
+ * @gpa: Guest physical address of fault.
+ * @write: Whether the fault was due to a write.
+ *
+ * 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
+ * -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_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, bool write)
+{
+ bool writeable;
+ int srcu_idx, err = 0, retry_no = 0;
+ unsigned long hva;
+ unsigned long mmu_seq;
+ unsigned long prot_bits;
+ pte_t *ptep, new_pte;
+ kvm_pfn_t pfn;
+ gfn_t gfn = gpa >> PAGE_SHIFT;
+ struct vm_area_struct *vma;
+ struct kvm *kvm = vcpu->kvm;
+ struct kvm_memory_slot *memslot;
+ struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
+
+ /* Try the fast path to handle old / clean pages */
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+ err = kvm_map_page_fast(vcpu, gpa, write);
+ if (!err)
+ goto out;
+
+ memslot = gfn_to_memslot(kvm, gfn);
+ hva = gfn_to_hva_memslot_prot(memslot, gfn, &writeable);
+ if (kvm_is_error_hva(hva) || (write && !writeable))
+ goto out;
+
+ mmap_read_lock(current->mm);
+ vma = find_vma_intersection(current->mm, hva, hva + 1);
+ if (unlikely(!vma)) {
+ kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
+ mmap_read_unlock(current->mm);
+ err = -EFAULT;
+ goto out;
+ }
+ mmap_read_unlock(current->mm);
+
+ /* 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_invalidate_seq;
+ /*
+ * Ensure the read of mmu_invalidate_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_invalidate_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_invalidate_invalidate_<page|range_end>() before
+ * mmu_invalidate_seq is incremented.
+ */
+ smp_rmb();
+
+ /* Slow path - ask KVM core whether we can access this GPA */
+ pfn = gfn_to_pfn_prot(kvm, gfn, write, &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_invalidate_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_set_pfn_accessed(pfn);
+ kvm_release_pfn_clean(pfn);
+ if (retry_no > 100) {
+ retry_no = 0;
+ schedule();
+ }
+ retry_no++;
+ goto retry;
+ }
+
+ /*
+ * For emulated devices such virtio device, actual cache attribute is
+ * determined by physical machine.
+ * For pass through physical device, it should be uncachable
+ */
+ prot_bits = _PAGE_PRESENT | __READABLE;
+ if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+ prot_bits |= _CACHE_SUC;
+ else
+ prot_bits |= _CACHE_CC;
+
+ if (writeable) {
+ prot_bits |= _PAGE_WRITE;
+ if (write) {
+ prot_bits |= __WRITEABLE;
+ mark_page_dirty(kvm, gfn);
+ kvm_set_pfn_dirty(pfn);
+ }
+ }
+
+ /* Ensure page tables are allocated */
+ ptep = kvm_pte_for_gpa(kvm, memcache, gpa);
+ new_pte = pfn_pte(pfn, __pgprot(prot_bits));
+ set_pte(ptep, new_pte);
+
+ err = 0;
+ 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;
+}
+
+int kvm_handle_mm_fault(struct kvm_vcpu *vcpu, unsigned long gpa, bool write)
+{
+ int ret;
+
+ ret = kvm_map_page(vcpu, gpa, write);
+ if (ret)
+ return ret;
+
+ /* Invalidate this entry in the TLB */
+ return kvm_flush_tlb_gpa(vcpu, gpa);
+}
+
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+
+}
+
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+ const struct kvm_memory_slot *old,
+ struct kvm_memory_slot *new,
+ enum kvm_mr_change change)
+{
+ return 0;
+}
+
+void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
+ const struct kvm_memory_slot *memslot)
+{
+ kvm_flush_remote_tlbs(kvm);
+}
