1 files changed, 299 insertions, 0 deletions

diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c
new file mode 100644
index 000000000000..ba2bcdde6221
--- /dev/null
+++ b/arch/x86/kvm/mmu_audit.c
@@ -0,0 +1,299 @@
+/*
+ * mmu_audit.c:
+ *
+ * Audit code for KVM MMU
+ *
+ * Copyright (C) 2006 Qumranet, Inc.
+ * Copyright 2010 Red Hat, Inc. and/or its affiliates.
+ *
+ * Authors:
+ *   Yaniv Kamay  <yaniv@qumranet.com>
+ *   Avi Kivity   <avi@qumranet.com>
+ *   Marcelo Tosatti <mtosatti@redhat.com>
+ *   Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <linux/ratelimit.h>
+
+static int audit_point;
+
+#define audit_printk(fmt, args...)              \
+        printk(KERN_ERR "audit: (%s) error: "   \
+                fmt, audit_point_name[audit_point], ##args)
+
+typedef void (*inspect_spte_fn) (struct kvm_vcpu *vcpu, u64 *sptep, int level);
+
+static void __mmu_spte_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+                            inspect_spte_fn fn, int level)
+{
+        int i;
+
+        for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+                u64 *ent = sp->spt;
+
+                fn(vcpu, ent + i, level);
+
+                if (is_shadow_present_pte(ent[i]) &&
+                      !is_last_spte(ent[i], level)) {
+                        struct kvm_mmu_page *child;
+
+                        child = page_header(ent[i] & PT64_BASE_ADDR_MASK);
+                        __mmu_spte_walk(vcpu, child, fn, level - 1);
+                }
+        }
+}
+
+static void mmu_spte_walk(struct kvm_vcpu *vcpu, inspect_spte_fn fn)
+{
+        int i;
+        struct kvm_mmu_page *sp;
+
+        if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+                return;
+
+        if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {
+                hpa_t root = vcpu->arch.mmu.root_hpa;
+
+                sp = page_header(root);
+                __mmu_spte_walk(vcpu, sp, fn, PT64_ROOT_LEVEL);
+                return;
+        }
+
+        for (i = 0; i < 4; ++i) {
+                hpa_t root = vcpu->arch.mmu.pae_root[i];
+
+                if (root && VALID_PAGE(root)) {
+                        root &= PT64_BASE_ADDR_MASK;
+                        sp = page_header(root);
+                        __mmu_spte_walk(vcpu, sp, fn, 2);
+                }
+        }
+
+        return;
+}
+
+typedef void (*sp_handler) (struct kvm *kvm, struct kvm_mmu_page *sp);
+
+static void walk_all_active_sps(struct kvm *kvm, sp_handler fn)
+{
+        struct kvm_mmu_page *sp;
+
+        list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link)
+                fn(kvm, sp);
+}
+
+static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level)
+{
+        struct kvm_mmu_page *sp;
+        gfn_t gfn;
+        pfn_t pfn;
+        hpa_t hpa;
+
+        sp = page_header(__pa(sptep));
+
+        if (sp->unsync) {
+                if (level != PT_PAGE_TABLE_LEVEL) {
+                        audit_printk("unsync sp: %p level = %d\n", sp, level);
+                        return;
+                }
+
+                if (*sptep == shadow_notrap_nonpresent_pte) {
+                        audit_printk("notrap spte in unsync sp: %p\n", sp);
+                        return;
+                }
+        }
+
+        if (sp->role.direct && *sptep == shadow_notrap_nonpresent_pte) {
+                audit_printk("notrap spte in direct sp: %p\n", sp);
+                return;
+        }
+
+        if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level))
+                return;
+
+        gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
+        pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn);
+
+        if (is_error_pfn(pfn)) {
+                kvm_release_pfn_clean(pfn);
+                return;
+        }
+
+        hpa =  pfn << PAGE_SHIFT;
+        if ((*sptep & PT64_BASE_ADDR_MASK) != hpa)
+                audit_printk("levels %d pfn %llx hpa %llx ent %llxn",
+                                   vcpu->arch.mmu.root_level, pfn, hpa, *sptep);
+}
+
+static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep)
+{
+        unsigned long *rmapp;
+        struct kvm_mmu_page *rev_sp;
+        gfn_t gfn;
+
+
+        rev_sp = page_header(__pa(sptep));
+        gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt);
+
+        if (!gfn_to_memslot(kvm, gfn)) {
+                if (!printk_ratelimit())
+                        return;
+                audit_printk("no memslot for gfn %llx\n", gfn);
+                audit_printk("index %ld of sp (gfn=%llx)\n",
+                       (long int)(sptep - rev_sp->spt), rev_sp->gfn);
+                dump_stack();
+                return;
+        }
+
+        rmapp = gfn_to_rmap(kvm, gfn, rev_sp->role.level);
+        if (!*rmapp) {
+                if (!printk_ratelimit())
+                        return;
+                audit_printk("no rmap for writable spte %llx\n", *sptep);
+                dump_stack();
+        }
+}
+
+static void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu, u64 *sptep, int level)
+{
+        if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep, level))
+                inspect_spte_has_rmap(vcpu->kvm, sptep);
+}
+
+static void audit_spte_after_sync(struct kvm_vcpu *vcpu, u64 *sptep, int level)
+{
+        struct kvm_mmu_page *sp = page_header(__pa(sptep));
+
+        if (audit_point == AUDIT_POST_SYNC && sp->unsync)
+                audit_printk("meet unsync sp(%p) after sync root.\n", sp);
+}
+
+static void check_mappings_rmap(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+        int i;
+
+        if (sp->role.level != PT_PAGE_TABLE_LEVEL)
+                return;
+
+        for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+                if (!is_rmap_spte(sp->spt[i]))
+                        continue;
+
+                inspect_spte_has_rmap(kvm, sp->spt + i);
+        }
+}
+
+static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+        struct kvm_memory_slot *slot;
+        unsigned long *rmapp;
+        u64 *spte;
+
+        if (sp->role.direct || sp->unsync || sp->role.invalid)
+                return;
+
+        slot = gfn_to_memslot(kvm, sp->gfn);
+        rmapp = &slot->rmap[sp->gfn - slot->base_gfn];
+
+        spte = rmap_next(kvm, rmapp, NULL);
+        while (spte) {
+                if (is_writable_pte(*spte))
+                        audit_printk("shadow page has writable mappings: gfn "
+                                     "%llx role %x\n", sp->gfn, sp->role.word);
+                spte = rmap_next(kvm, rmapp, spte);
+        }
+}
+
+static void audit_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+        check_mappings_rmap(kvm, sp);
+        audit_write_protection(kvm, sp);
+}
+
+static void audit_all_active_sps(struct kvm *kvm)
+{
+        walk_all_active_sps(kvm, audit_sp);
+}
+
+static void audit_spte(struct kvm_vcpu *vcpu, u64 *sptep, int level)
+{
+        audit_sptes_have_rmaps(vcpu, sptep, level);
+        audit_mappings(vcpu, sptep, level);
+        audit_spte_after_sync(vcpu, sptep, level);
+}
+
+static void audit_vcpu_spte(struct kvm_vcpu *vcpu)
+{
+        mmu_spte_walk(vcpu, audit_spte);
+}
+
+static void kvm_mmu_audit(void *ignore, struct kvm_vcpu *vcpu, int point)
+{
+        static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
+
+        if (!__ratelimit(&ratelimit_state))
+                return;
+
+        audit_point = point;
+        audit_all_active_sps(vcpu->kvm);
+        audit_vcpu_spte(vcpu);
+}
+
+static bool mmu_audit;
+
+static void mmu_audit_enable(void)
+{
+        int ret;
+
+        if (mmu_audit)
+                return;
+
+        ret = register_trace_kvm_mmu_audit(kvm_mmu_audit, NULL);
+        WARN_ON(ret);
+
+        mmu_audit = true;
+}
+
+static void mmu_audit_disable(void)
+{
+        if (!mmu_audit)
+                return;
+
+        unregister_trace_kvm_mmu_audit(kvm_mmu_audit, NULL);
+        tracepoint_synchronize_unregister();
+        mmu_audit = false;
+}
+
+static int mmu_audit_set(const char *val, const struct kernel_param *kp)
+{
+        int ret;
+        unsigned long enable;
+
+        ret = strict_strtoul(val, 10, &enable);
+        if (ret < 0)
+                return -EINVAL;
+
+        switch (enable) {
+        case 0:
+                mmu_audit_disable();
+                break;
+        case 1:
+                mmu_audit_enable();
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static struct kernel_param_ops audit_param_ops = {
+        .set = mmu_audit_set,
+        .get = param_get_bool,
+};
+
+module_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644);