1 files changed, 303 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/mmu_audit.c b/arch/x86/kvm/mmu/mmu_audit.c
new file mode 100644
index 000000000000..9d2844f87f6d
--- /dev/null
+++ b/arch/x86/kvm/mmu/mmu_audit.c
@@ -0,0 +1,303 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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>
+ */
+
+#include <linux/ratelimit.h>
+
+static char const *audit_point_name[] = {
+	"pre page fault",
+	"post page fault",
+	"pre pte write",
+	"post pte write",
+	"pre sync",
+	"post sync"
+};
+
+#define audit_printk(kvm, fmt, args...)		\
+	printk(KERN_ERR "audit: (%s) error: "	\
+		fmt, audit_point_name[kvm->arch.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_4LEVEL) {
+		hpa_t root = vcpu->arch.mmu->root_hpa;
+
+		sp = page_header(root);
+		__mmu_spte_walk(vcpu, sp, fn, vcpu->arch.mmu->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;
+	kvm_pfn_t pfn;
+	hpa_t hpa;
+
+	sp = page_header(__pa(sptep));
+
+	if (sp->unsync) {
+		if (level != PG_LEVEL_4K) {
+			audit_printk(vcpu->kvm, "unsync sp: %p "
+				     "level = %d\n", sp, level);
+			return;
+		}
+	}
+
+	if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level))
+		return;
+
+	gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
+	pfn = kvm_vcpu_gfn_to_pfn_atomic(vcpu, gfn);
+
+	if (is_error_pfn(pfn))
+		return;
+
+	hpa =  pfn << PAGE_SHIFT;
+	if ((*sptep & PT64_BASE_ADDR_MASK) != hpa)
+		audit_printk(vcpu->kvm, "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)
+{
+	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
+	struct kvm_rmap_head *rmap_head;
+	struct kvm_mmu_page *rev_sp;
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *slot;
+	gfn_t gfn;
+
+	rev_sp = page_header(__pa(sptep));
+	gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt);
+
+	slots = kvm_memslots_for_spte_role(kvm, rev_sp->role);
+	slot = __gfn_to_memslot(slots, gfn);
+	if (!slot) {
+		if (!__ratelimit(&ratelimit_state))
+			return;
+		audit_printk(kvm, "no memslot for gfn %llx\n", gfn);
+		audit_printk(kvm, "index %ld of sp (gfn=%llx)\n",
+		       (long int)(sptep - rev_sp->spt), rev_sp->gfn);
+		dump_stack();
+		return;
+	}
+
+	rmap_head = __gfn_to_rmap(gfn, rev_sp->role.level, slot);
+	if (!rmap_head->val) {
+		if (!__ratelimit(&ratelimit_state))
+			return;
+		audit_printk(kvm, "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 (vcpu->kvm->arch.audit_point == AUDIT_POST_SYNC && sp->unsync)
+		audit_printk(vcpu->kvm, "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 != PG_LEVEL_4K)
+		return;
+
+	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+		if (!is_shadow_present_pte(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_rmap_head *rmap_head;
+	u64 *sptep;
+	struct rmap_iterator iter;
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *slot;
+
+	if (sp->role.direct || sp->unsync || sp->role.invalid)
+		return;
+
+	slots = kvm_memslots_for_spte_role(kvm, sp->role);
+	slot = __gfn_to_memslot(slots, sp->gfn);
+	rmap_head = __gfn_to_rmap(sp->gfn, PG_LEVEL_4K, slot);
+
+	for_each_rmap_spte(rmap_head, &iter, sptep) {
+		if (is_writable_pte(*sptep))
+			audit_printk(kvm, "shadow page has writable "
+				     "mappings: gfn %llx role %x\n",
+				     sp->gfn, sp->role.word);
+	}
+}
+
+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 bool mmu_audit;
+static struct static_key mmu_audit_key;
+
+static void __kvm_mmu_audit(struct kvm_vcpu *vcpu, int point)
+{
+	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
+
+	if (!__ratelimit(&ratelimit_state))
+		return;
+
+	vcpu->kvm->arch.audit_point = point;
+	audit_all_active_sps(vcpu->kvm);
+	audit_vcpu_spte(vcpu);
+}
+
+static inline void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point)
+{
+	if (static_key_false((&mmu_audit_key)))
+		__kvm_mmu_audit(vcpu, point);
+}
+
+static void mmu_audit_enable(void)
+{
+	if (mmu_audit)
+		return;
+
+	static_key_slow_inc(&mmu_audit_key);
+	mmu_audit = true;
+}
+
+static void mmu_audit_disable(void)
+{
+	if (!mmu_audit)
+		return;
+
+	static_key_slow_dec(&mmu_audit_key);
+	mmu_audit = false;
+}
+
+static int mmu_audit_set(const char *val, const struct kernel_param *kp)
+{
+	int ret;
+	unsigned long enable;
+
+	ret = kstrtoul(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 const struct kernel_param_ops audit_param_ops = {
+	.set = mmu_audit_set,
+	.get = param_get_bool,
+};
+
+arch_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644);