1 files changed, 461 insertions, 0 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
new file mode 100644
index 000000000000..56b88f7e83ef
--- /dev/null
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -0,0 +1,461 @@
+/*
+ * Kernel-based Virtual Machine driver for Linux
+ *
+ * This module enables machines with Intel VT-x extensions to run virtual
+ * machines without emulation or binary translation.
+ *
+ * MMU support
+ *
+ * Copyright (C) 2006 Qumranet, Inc.
+ *
+ * Authors:
+ *   Yaniv Kamay  <yaniv@qumranet.com>
+ *   Avi Kivity   <avi@qumranet.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+/*
+ * We need the mmu code to access both 32-bit and 64-bit guest ptes,
+ * so the code in this file is compiled twice, once per pte size.
+ */
+
+#if PTTYPE == 64
+        #define pt_element_t u64
+        #define guest_walker guest_walker64
+        #define FNAME(name) paging##64_##name
+        #define PT_BASE_ADDR_MASK PT64_BASE_ADDR_MASK
+        #define PT_DIR_BASE_ADDR_MASK PT64_DIR_BASE_ADDR_MASK
+        #define PT_INDEX(addr, level) PT64_INDEX(addr, level)
+        #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
+        #define PT_LEVEL_MASK(level) PT64_LEVEL_MASK(level)
+        #define PT_LEVEL_BITS PT64_LEVEL_BITS
+        #ifdef CONFIG_X86_64
+        #define PT_MAX_FULL_LEVELS 4
+        #define CMPXCHG cmpxchg
+        #else
+        #define CMPXCHG cmpxchg64
+        #define PT_MAX_FULL_LEVELS 2
+        #endif
+#elif PTTYPE == 32
+        #define pt_element_t u32
+        #define guest_walker guest_walker32
+        #define FNAME(name) paging##32_##name
+        #define PT_BASE_ADDR_MASK PT32_BASE_ADDR_MASK
+        #define PT_DIR_BASE_ADDR_MASK PT32_DIR_BASE_ADDR_MASK
+        #define PT_INDEX(addr, level) PT32_INDEX(addr, level)
+        #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
+        #define PT_LEVEL_MASK(level) PT32_LEVEL_MASK(level)
+        #define PT_LEVEL_BITS PT32_LEVEL_BITS
+        #define PT_MAX_FULL_LEVELS 2
+        #define CMPXCHG cmpxchg
+#else
+        #error Invalid PTTYPE value
+#endif
+
+#define gpte_to_gfn FNAME(gpte_to_gfn)
+#define gpte_to_gfn_pde FNAME(gpte_to_gfn_pde)
+
+/*
+ * The guest_walker structure emulates the behavior of the hardware page
+ * table walker.
+ */
+struct guest_walker {
+        int level;
+        gfn_t table_gfn[PT_MAX_FULL_LEVELS];
+        pt_element_t ptes[PT_MAX_FULL_LEVELS];
+        gpa_t pte_gpa[PT_MAX_FULL_LEVELS];
+        unsigned pt_access;
+        unsigned pte_access;
+        gfn_t gfn;
+        u32 error_code;
+};
+
+static gfn_t gpte_to_gfn(pt_element_t gpte)
+{
+        return (gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
+}
+
+static gfn_t gpte_to_gfn_pde(pt_element_t gpte)
+{
+        return (gpte & PT_DIR_BASE_ADDR_MASK) >> PAGE_SHIFT;
+}
+
+static bool FNAME(cmpxchg_gpte)(struct kvm *kvm,
+                         gfn_t table_gfn, unsigned index,
+                         pt_element_t orig_pte, pt_element_t new_pte)
+{
+        pt_element_t ret;
+        pt_element_t *table;
+        struct page *page;
+
+        page = gfn_to_page(kvm, table_gfn);
+        table = kmap_atomic(page, KM_USER0);
+
+        ret = CMPXCHG(&table[index], orig_pte, new_pte);
+
+        kunmap_atomic(table, KM_USER0);
+
+        kvm_release_page_dirty(page);
+
+        return (ret != orig_pte);
+}
+
+static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
+{
+        unsigned access;
+
+        access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK;
+#if PTTYPE == 64
+        if (is_nx(vcpu))
+                access &= ~(gpte >> PT64_NX_SHIFT);
+#endif
+        return access;
+}
+
+/*
+ * Fetch a guest pte for a guest virtual address
+ */
+static int FNAME(walk_addr)(struct guest_walker *walker,
+                            struct kvm_vcpu *vcpu, gva_t addr,
+                            int write_fault, int user_fault, int fetch_fault)
+{
+        pt_element_t pte;
+        gfn_t table_gfn;
+        unsigned index, pt_access, pte_access;
+        gpa_t pte_gpa;
+
+        pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
+walk:
+        walker->level = vcpu->arch.mmu.root_level;
+        pte = vcpu->arch.cr3;
+#if PTTYPE == 64
+        if (!is_long_mode(vcpu)) {
+                pte = vcpu->arch.pdptrs[(addr >> 30) & 3];
+                if (!is_present_pte(pte))
+                        goto not_present;
+                --walker->level;
+        }
+#endif
+        ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
+               (vcpu->cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
+
+        pt_access = ACC_ALL;
+
+        for (;;) {
+                index = PT_INDEX(addr, walker->level);
+
+                table_gfn = gpte_to_gfn(pte);
+                pte_gpa = gfn_to_gpa(table_gfn);
+                pte_gpa += index * sizeof(pt_element_t);
+                walker->table_gfn[walker->level - 1] = table_gfn;
+                walker->pte_gpa[walker->level - 1] = pte_gpa;
+                pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
+                         walker->level - 1, table_gfn);
+
+                kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte));
+
+                if (!is_present_pte(pte))
+                        goto not_present;
+
+                if (write_fault && !is_writeble_pte(pte))
+                        if (user_fault || is_write_protection(vcpu))
+                                goto access_error;
+
+                if (user_fault && !(pte & PT_USER_MASK))
+                        goto access_error;
+
+#if PTTYPE == 64
+                if (fetch_fault && is_nx(vcpu) && (pte & PT64_NX_MASK))
+                        goto access_error;
+#endif
+
+                if (!(pte & PT_ACCESSED_MASK)) {
+                        mark_page_dirty(vcpu->kvm, table_gfn);
+                        if (FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn,
+                            index, pte, pte|PT_ACCESSED_MASK))
+                                goto walk;
+                        pte |= PT_ACCESSED_MASK;
+                }
+
+                pte_access = pt_access & FNAME(gpte_access)(vcpu, pte);
+
+                walker->ptes[walker->level - 1] = pte;
+
+                if (walker->level == PT_PAGE_TABLE_LEVEL) {
+                        walker->gfn = gpte_to_gfn(pte);
+                        break;
+                }
+
+                if (walker->level == PT_DIRECTORY_LEVEL
+                    && (pte & PT_PAGE_SIZE_MASK)
+                    && (PTTYPE == 64 || is_pse(vcpu))) {
+                        walker->gfn = gpte_to_gfn_pde(pte);
+                        walker->gfn += PT_INDEX(addr, PT_PAGE_TABLE_LEVEL);
+                        if (PTTYPE == 32 && is_cpuid_PSE36())
+                                walker->gfn += pse36_gfn_delta(pte);
+                        break;
+                }
+
+                pt_access = pte_access;
+                --walker->level;
+        }
+
+        if (write_fault && !is_dirty_pte(pte)) {
+                bool ret;
+
+                mark_page_dirty(vcpu->kvm, table_gfn);
+                ret = FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn, index, pte,
+                            pte|PT_DIRTY_MASK);
+                if (ret)
+                        goto walk;
+                pte |= PT_DIRTY_MASK;
+                kvm_mmu_pte_write(vcpu, pte_gpa, (u8 *)&pte, sizeof(pte));
+                walker->ptes[walker->level - 1] = pte;
+        }
+
+        walker->pt_access = pt_access;
+        walker->pte_access = pte_access;
+        pgprintk("%s: pte %llx pte_access %x pt_access %x\n",
+                 __FUNCTION__, (u64)pte, pt_access, pte_access);
+        return 1;
+
+not_present:
+        walker->error_code = 0;
+        goto err;
+
+access_error:
+        walker->error_code = PFERR_PRESENT_MASK;
+
+err:
+        if (write_fault)
+                walker->error_code |= PFERR_WRITE_MASK;
+        if (user_fault)
+                walker->error_code |= PFERR_USER_MASK;
+        if (fetch_fault)
+                walker->error_code |= PFERR_FETCH_MASK;
+        return 0;
+}
+
+static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
+                              u64 *spte, const void *pte, int bytes,
+                              int offset_in_pte)
+{
+        pt_element_t gpte;
+        unsigned pte_access;
+
+        gpte = *(const pt_element_t *)pte;
+        if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
+                if (!offset_in_pte && !is_present_pte(gpte))
+                        set_shadow_pte(spte, shadow_notrap_nonpresent_pte);
+                return;
+        }
+        if (bytes < sizeof(pt_element_t))
+                return;
+        pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);
+        pte_access = page->role.access & FNAME(gpte_access)(vcpu, gpte);
+        mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
+                     gpte & PT_DIRTY_MASK, NULL, gpte_to_gfn(gpte));
+}
+
+/*
+ * Fetch a shadow pte for a specific level in the paging hierarchy.
+ */
+static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
+                         struct guest_walker *walker,
+                         int user_fault, int write_fault, int *ptwrite)
+{
+        hpa_t shadow_addr;
+        int level;
+        u64 *shadow_ent;
+        unsigned access = walker->pt_access;
+
+        if (!is_present_pte(walker->ptes[walker->level - 1]))
+                return NULL;
+
+        shadow_addr = vcpu->arch.mmu.root_hpa;
+        level = vcpu->arch.mmu.shadow_root_level;
+        if (level == PT32E_ROOT_LEVEL) {
+                shadow_addr = vcpu->arch.mmu.pae_root[(addr >> 30) & 3];
+                shadow_addr &= PT64_BASE_ADDR_MASK;
+                --level;
+        }
+
+        for (; ; level--) {
+                u32 index = SHADOW_PT_INDEX(addr, level);
+                struct kvm_mmu_page *shadow_page;
+                u64 shadow_pte;
+                int metaphysical;
+                gfn_t table_gfn;
+                bool new_page = 0;
+
+                shadow_ent = ((u64 *)__va(shadow_addr)) + index;
+                if (is_shadow_present_pte(*shadow_ent)) {
+                        if (level == PT_PAGE_TABLE_LEVEL)
+                                break;
+                        shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK;
+                        continue;
+                }
+
+                if (level == PT_PAGE_TABLE_LEVEL)
+                        break;
+
+                if (level - 1 == PT_PAGE_TABLE_LEVEL
+                    && walker->level == PT_DIRECTORY_LEVEL) {
+                        metaphysical = 1;
+                        if (!is_dirty_pte(walker->ptes[level - 1]))
+                                access &= ~ACC_WRITE_MASK;
+                        table_gfn = gpte_to_gfn(walker->ptes[level - 1]);
+                } else {
+                        metaphysical = 0;
+                        table_gfn = walker->table_gfn[level - 2];
+                }
+                shadow_page = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
+                                               metaphysical, access,
+                                               shadow_ent, &new_page);
+                if (new_page && !metaphysical) {
+                        pt_element_t curr_pte;
+                        kvm_read_guest(vcpu->kvm, walker->pte_gpa[level - 2],
+                                       &curr_pte, sizeof(curr_pte));
+                        if (curr_pte != walker->ptes[level - 2])
+                                return NULL;
+                }
+                shadow_addr = __pa(shadow_page->spt);
+                shadow_pte = shadow_addr | PT_PRESENT_MASK | PT_ACCESSED_MASK
+                        | PT_WRITABLE_MASK | PT_USER_MASK;
+                *shadow_ent = shadow_pte;
+        }
+
+        mmu_set_spte(vcpu, shadow_ent, access, walker->pte_access & access,
+                     user_fault, write_fault,
+                     walker->ptes[walker->level-1] & PT_DIRTY_MASK,
+                     ptwrite, walker->gfn);
+
+        return shadow_ent;
+}
+
+/*
+ * Page fault handler.  There are several causes for a page fault:
+ *   - there is no shadow pte for the guest pte
+ *   - write access through a shadow pte marked read only so that we can set
+ *     the dirty bit
+ *   - write access to a shadow pte marked read only so we can update the page
+ *     dirty bitmap, when userspace requests it
+ *   - mmio access; in this case we will never install a present shadow pte
+ *   - normal guest page fault due to the guest pte marked not present, not
+ *     writable, or not executable
+ *
+ *  Returns: 1 if we need to emulate the instruction, 0 otherwise, or
+ *           a negative value on error.
+ */
+static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
+                               u32 error_code)
+{
+        int write_fault = error_code & PFERR_WRITE_MASK;
+        int user_fault = error_code & PFERR_USER_MASK;
+        int fetch_fault = error_code & PFERR_FETCH_MASK;
+        struct guest_walker walker;
+        u64 *shadow_pte;
+        int write_pt = 0;
+        int r;
+
+        pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);
+        kvm_mmu_audit(vcpu, "pre page fault");
+
+        r = mmu_topup_memory_caches(vcpu);
+        if (r)
+                return r;
+
+        /*
+         * Look up the shadow pte for the faulting address.
+         */
+        r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
+                             fetch_fault);
+
+        /*
+         * The page is not mapped by the guest.  Let the guest handle it.
+         */
+        if (!r) {
+                pgprintk("%s: guest page fault\n", __FUNCTION__);
+                inject_page_fault(vcpu, addr, walker.error_code);
+                vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
+                return 0;
+        }
+
+        shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
+                                  &write_pt);
+        pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
+                 shadow_pte, *shadow_pte, write_pt);
+
+        if (!write_pt)
+                vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
+
+        /*
+         * mmio: emulate if accessible, otherwise its a guest fault.
+         */
+        if (shadow_pte && is_io_pte(*shadow_pte))
+                return 1;
+
+        ++vcpu->stat.pf_fixed;
+        kvm_mmu_audit(vcpu, "post page fault (fixed)");
+
+        return write_pt;
+}
+
+static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
+{
+        struct guest_walker walker;
+        gpa_t gpa = UNMAPPED_GVA;
+        int r;
+
+        r = FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0, 0);
+
+        if (r) {
+                gpa = gfn_to_gpa(walker.gfn);
+                gpa |= vaddr & ~PAGE_MASK;
+        }
+
+        return gpa;
+}
+
+static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
+                                 struct kvm_mmu_page *sp)
+{
+        int i, offset = 0;
+        pt_element_t *gpt;
+        struct page *page;
+
+        if (sp->role.metaphysical
+            || (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
+                nonpaging_prefetch_page(vcpu, sp);
+                return;
+        }
+
+        if (PTTYPE == 32)
+                offset = sp->role.quadrant << PT64_LEVEL_BITS;
+        page = gfn_to_page(vcpu->kvm, sp->gfn);
+        gpt = kmap_atomic(page, KM_USER0);
+        for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
+                if (is_present_pte(gpt[offset + i]))
+                        sp->spt[i] = shadow_trap_nonpresent_pte;
+                else
+                        sp->spt[i] = shadow_notrap_nonpresent_pte;
+        kunmap_atomic(gpt, KM_USER0);
+        kvm_release_page_clean(page);
+}
+
+#undef pt_element_t
+#undef guest_walker
+#undef FNAME
+#undef PT_BASE_ADDR_MASK
+#undef PT_INDEX
+#undef SHADOW_PT_INDEX
+#undef PT_LEVEL_MASK
+#undef PT_DIR_BASE_ADDR_MASK
+#undef PT_LEVEL_BITS
+#undef PT_MAX_FULL_LEVELS
+#undef gpte_to_gfn
+#undef gpte_to_gfn_pde
+#undef CMPXCHG