arch/x86/kvm/mmu_audit.c - kernel/msm-5.4 - Gitiles

 /*
  * mmu_audit.c:
  *
  * Audit code for KVM MMU
  *
  * Copyright (C) 2006 Qumranet, Inc.
  * Copyright 2010 Red Hat, Inc. and/or its affilates.
  *
  * 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.
  *
  */

 static const char *audit_msg;

 typedef void (*inspect_spte_fn) (struct kvm *kvm, u64 *sptep);

 static void __mmu_spte_walk(struct kvm *kvm, struct kvm_mmu_page *sp,
 			    inspect_spte_fn fn)
 {
 	int i;

 	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
 		u64 ent = sp->spt[i];

 		if (is_shadow_present_pte(ent)) {
 			if (!is_last_spte(ent, sp->role.level)) {
 				struct kvm_mmu_page *child;
 				child = page_header(ent & PT64_BASE_ADDR_MASK);
 				__mmu_spte_walk(kvm, child, fn);
 			} else
 				fn(kvm, &sp->spt[i]);
 		}
 	}
 }

 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.shadow_root_level == PT64_ROOT_LEVEL) {
 		hpa_t root = vcpu->arch.mmu.root_hpa;
 		sp = page_header(root);
 		__mmu_spte_walk(vcpu->kvm, sp, fn);
 		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->kvm, sp, fn);
 		}
 	}
 	return;
 }

 static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
 				gva_t va, int level)
 {
 	u64 *pt = __va(page_pte & PT64_BASE_ADDR_MASK);
 	int i;
 	gva_t va_delta = 1ul << (PAGE_SHIFT + 9 * (level - 1));

 	for (i = 0; i < PT64_ENT_PER_PAGE; ++i, va += va_delta) {
 		u64 *sptep = pt + i;
 		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) {
 				printk(KERN_ERR "audit: (%s) error: unsync sp: %p level = %d\n",
 						audit_msg, sp, level);
 				return;
 			}

 			if (*sptep == shadow_notrap_nonpresent_pte) {
 				printk(KERN_ERR "audit: (%s) error: notrap spte in unsync sp: %p\n",
 						audit_msg, sp);
 				return;
 			}
 		}

 		if (sp->role.direct && *sptep == shadow_notrap_nonpresent_pte) {
 			printk(KERN_ERR "audit: (%s) error: notrap spte in direct sp: %p\n",
 					audit_msg, 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)
 			printk(KERN_ERR "xx audit error: (%s) levels %d"
 					   " gva %lx pfn %llx hpa %llx ent %llxn",
 					   audit_msg, vcpu->arch.mmu.root_level,
 					   va, pfn, hpa, *sptep);
 	}
 }

 static void audit_mappings(struct kvm_vcpu *vcpu)
 {
 	unsigned i;

 	if (vcpu->arch.mmu.root_level == 4)
 		audit_mappings_page(vcpu, vcpu->arch.mmu.root_hpa, 0, 4);
 	else
 		for (i = 0; i < 4; ++i)
 			if (vcpu->arch.mmu.pae_root[i] & PT_PRESENT_MASK)
 				audit_mappings_page(vcpu,
 						    vcpu->arch.mmu.pae_root[i],
 						    i << 30,
 						    2);
 }

 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;
 		printk(KERN_ERR "%s: no memslot for gfn %llx\n",
 				 audit_msg, gfn);
 		printk(KERN_ERR "%s: index %ld of sp (gfn=%llx)\n",
 		       audit_msg, (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;
 		printk(KERN_ERR "%s: no rmap for writable spte %llx\n",
 				 audit_msg, *sptep);
 		dump_stack();
 	}
 }

 void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu)
 {
 	mmu_spte_walk(vcpu, inspect_spte_has_rmap);
 }

 static void check_mappings_rmap(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu_page *sp;
 	int i;

 	list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
 		u64 *pt = sp->spt;

 		if (sp->role.level != PT_PAGE_TABLE_LEVEL)
 			continue;

 		for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
 			if (!is_rmap_spte(pt[i]))
 				continue;

 			inspect_spte_has_rmap(vcpu->kvm, &pt[i]);
 		}
 	}
 	return;
 }

 static void audit_rmap(struct kvm_vcpu *vcpu)
 {
 	check_mappings_rmap(vcpu);
 }

 static void audit_write_protection(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu_page *sp;
 	struct kvm_memory_slot *slot;
 	unsigned long *rmapp;
 	u64 *spte;

 	list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
 		if (sp->role.direct)
 			continue;
 		if (sp->unsync)
 			continue;
 		if (sp->role.invalid)
 			continue;

 		slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
 		rmapp = &slot->rmap[sp->gfn - slot->base_gfn];

 		spte = rmap_next(vcpu->kvm, rmapp, NULL);
 		while (spte) {
 			if (is_writable_pte(*spte))
 				printk(KERN_ERR "%s: (%s) shadow page has "
 				"writable mappings: gfn %llx role %x\n",
 			       __func__, audit_msg, sp->gfn,
 			       sp->role.word);
 			spte = rmap_next(vcpu->kvm, rmapp, spte);
 		}
 	}
 }

 static void kvm_mmu_audit(void *ignore, struct kvm_vcpu *vcpu, int audit_point)
 {
 	audit_msg = audit_point_name[audit_point];
 	audit_rmap(vcpu);
 	audit_write_protection(vcpu);
 	if (strcmp("pre pte write", audit_msg) != 0)
 		audit_mappings(vcpu);
 	audit_sptes_have_rmaps(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);
	/*
	* mmu_audit.c:
	*
	* Audit code for KVM MMU
	*
	* Copyright (C) 2006 Qumranet, Inc.
	* Copyright 2010 Red Hat, Inc. and/or its affilates.
	*
	* 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.
	*
	*/

	static const char *audit_msg;

	typedef void (inspect_spte_fn) (struct kvm kvm, u64 *sptep);

	static void __mmu_spte_walk(struct kvm kvm, struct kvm_mmu_page sp,
	inspect_spte_fn fn)
	{
	int i;

	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
	u64 ent = sp->spt[i];

	if (is_shadow_present_pte(ent)) {
	if (!is_last_spte(ent, sp->role.level)) {
	struct kvm_mmu_page *child;
	child = page_header(ent & PT64_BASE_ADDR_MASK);
	__mmu_spte_walk(kvm, child, fn);
	} else
	fn(kvm, &sp->spt[i]);
	}
	}
	}

	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.shadow_root_level == PT64_ROOT_LEVEL) {
	hpa_t root = vcpu->arch.mmu.root_hpa;
	sp = page_header(root);
	__mmu_spte_walk(vcpu->kvm, sp, fn);
	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->kvm, sp, fn);
	}
	}
	return;
	}

	static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
	gva_t va, int level)
	{
	u64 *pt = __va(page_pte & PT64_BASE_ADDR_MASK);
	int i;
	gva_t va_delta = 1ul << (PAGE_SHIFT + 9 * (level - 1));

	for (i = 0; i < PT64_ENT_PER_PAGE; ++i, va += va_delta) {
	u64 *sptep = pt + i;
	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) {
	printk(KERN_ERR "audit: (%s) error: unsync sp: %p level = %d\n",
	audit_msg, sp, level);
	return;
	}

	if (*sptep == shadow_notrap_nonpresent_pte) {
	printk(KERN_ERR "audit: (%s) error: notrap spte in unsync sp: %p\n",
	audit_msg, sp);
	return;
	}
	}

	if (sp->role.direct && *sptep == shadow_notrap_nonpresent_pte) {
	printk(KERN_ERR "audit: (%s) error: notrap spte in direct sp: %p\n",
	audit_msg, 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)
	printk(KERN_ERR "xx audit error: (%s) levels %d"
	" gva %lx pfn %llx hpa %llx ent %llxn",
	audit_msg, vcpu->arch.mmu.root_level,
	va, pfn, hpa, *sptep);
	}
	}

	static void audit_mappings(struct kvm_vcpu *vcpu)
	{
	unsigned i;

	if (vcpu->arch.mmu.root_level == 4)
	audit_mappings_page(vcpu, vcpu->arch.mmu.root_hpa, 0, 4);
	else
	for (i = 0; i < 4; ++i)
	if (vcpu->arch.mmu.pae_root[i] & PT_PRESENT_MASK)
	audit_mappings_page(vcpu,
	vcpu->arch.mmu.pae_root[i],
	i << 30,
	2);
	}

	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;
	printk(KERN_ERR "%s: no memslot for gfn %llx\n",
	audit_msg, gfn);
	printk(KERN_ERR "%s: index %ld of sp (gfn=%llx)\n",
	audit_msg, (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;
	printk(KERN_ERR "%s: no rmap for writable spte %llx\n",
	audit_msg, *sptep);
	dump_stack();
	}
	}

	void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu)
	{
	mmu_spte_walk(vcpu, inspect_spte_has_rmap);
	}

	static void check_mappings_rmap(struct kvm_vcpu *vcpu)
	{
	struct kvm_mmu_page *sp;
	int i;

	list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
	u64 *pt = sp->spt;

	if (sp->role.level != PT_PAGE_TABLE_LEVEL)
	continue;

	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
	if (!is_rmap_spte(pt[i]))
	continue;

	inspect_spte_has_rmap(vcpu->kvm, &pt[i]);
	}
	}
	return;
	}

	static void audit_rmap(struct kvm_vcpu *vcpu)
	{
	check_mappings_rmap(vcpu);
	}

	static void audit_write_protection(struct kvm_vcpu *vcpu)
	{
	struct kvm_mmu_page *sp;
	struct kvm_memory_slot *slot;
	unsigned long *rmapp;
	u64 *spte;

	list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
	if (sp->role.direct)
	continue;
	if (sp->unsync)
	continue;
	if (sp->role.invalid)
	continue;

	slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
	rmapp = &slot->rmap[sp->gfn - slot->base_gfn];

	spte = rmap_next(vcpu->kvm, rmapp, NULL);
	while (spte) {
	if (is_writable_pte(*spte))
	printk(KERN_ERR "%s: (%s) shadow page has "
	"writable mappings: gfn %llx role %x\n",
	__func__, audit_msg, sp->gfn,
	sp->role.word);
	spte = rmap_next(vcpu->kvm, rmapp, spte);
	}
	}
	}

	static void kvm_mmu_audit(void ignore, struct kvm_vcpu vcpu, int audit_point)
	{
	audit_msg = audit_point_name[audit_point];
	audit_rmap(vcpu);
	audit_write_protection(vcpu);
	if (strcmp("pre pte write", audit_msg) != 0)
	audit_mappings(vcpu);
	audit_sptes_have_rmaps(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);