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Commit 8b1fe17c authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: MMU: support disable/enable mmu audit dynamicly 



Add a r/w module parameter named 'mmu_audit', it can control audit
enable/disable:

enable:
  echo 1 > /sys/module/kvm/parameters/mmu_audit

disable:
  echo 0 > /sys/module/kvm/parameters/mmu_audit

This patch not change the logic

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 84e0cefa

arch/x86/kvm/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -64,6 +64,13 @@ config KVM_AMD 
	  To compile this as a module, choose M here: the module

	  will be called kvm-amd.



config KVM_MMU_AUDIT

	bool "Audit KVM MMU"

	depends on KVM && TRACEPOINTS

	---help---

	 This option adds a R/W kVM module parameter 'mmu_audit', which allows

	 audit  KVM MMU at runtime.



# OK, it's a little counter-intuitive to do this, but it puts it neatly under

# the virtualization menu.

source drivers/vhost/Kconfig

arch/x86/kvm/mmu.c

+73 −18
Original line number Diff line number Diff line
@@ -49,15 +49,21 @@ 
 */

bool tdp_enabled = false;



#undef MMU_DEBUG

enum {

	AUDIT_PRE_PAGE_FAULT,

	AUDIT_POST_PAGE_FAULT,

	AUDIT_PRE_PTE_WRITE,

	AUDIT_POST_PTE_WRITE

};



#undef AUDIT

char *audit_point_name[] = {

	"pre page fault",

	"post page fault",

	"pre pte write",

	"post pte write"

};



#ifdef AUDIT

static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg);

#else

static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg) {}

#endif

#undef MMU_DEBUG



#ifdef MMU_DEBUG
@@ -71,7 +77,7 @@ static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg) {} 


#endif



#if defined(MMU_DEBUG) || defined(AUDIT)

#ifdef MMU_DEBUG

static int dbg = 0;

module_param(dbg, bool, 0644);

#endif
@@ -2964,7 +2970,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, 
	kvm_mmu_access_page(vcpu, gfn);

	kvm_mmu_free_some_pages(vcpu);

	++vcpu->kvm->stat.mmu_pte_write;

	kvm_mmu_audit(vcpu, "pre pte write");

	trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);

	if (guest_initiated) {

		if (gfn == vcpu->arch.last_pt_write_gfn

		    && !last_updated_pte_accessed(vcpu)) {
@@ -3037,7 +3043,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, 
	}

	mmu_pte_write_flush_tlb(vcpu, zap_page, remote_flush, local_flush);

	kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);

	kvm_mmu_audit(vcpu, "post pte write");

	trace_kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE);

	spin_unlock(&vcpu->kvm->mmu_lock);

	if (!is_error_pfn(vcpu->arch.update_pte.pfn)) {

		kvm_release_pfn_clean(vcpu->arch.update_pte.pfn);
@@ -3483,8 +3489,7 @@ int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4]) 
}

EXPORT_SYMBOL_GPL(kvm_mmu_get_spte_hierarchy);



#ifdef AUDIT



#ifdef CONFIG_KVM_MMU_AUDIT

static const char *audit_msg;



typedef void (*inspect_spte_fn) (struct kvm *kvm, u64 *sptep);
@@ -3699,18 +3704,68 @@ static void audit_write_protection(struct kvm_vcpu *vcpu) 
	}

}



static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg)

static void kvm_mmu_audit(void *ignore, struct kvm_vcpu *vcpu, int audit_point)

{

	int olddbg = dbg;



	dbg = 0;

	audit_msg = msg;

	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);

	dbg = olddbg;

}



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);

#endif

arch/x86/kvm/mmutrace.h

+19 −0
Original line number Diff line number Diff line
@@ -195,6 +195,25 @@ DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page, 


	TP_ARGS(sp)

);



TRACE_EVENT(

	kvm_mmu_audit,

	TP_PROTO(struct kvm_vcpu *vcpu, int audit_point),

	TP_ARGS(vcpu, audit_point),



	TP_STRUCT__entry(

		__field(struct kvm_vcpu *, vcpu)

		__field(int, audit_point)

	),



	TP_fast_assign(

		__entry->vcpu = vcpu;

		__entry->audit_point = audit_point;

	),



	TP_printk("vcpu:%d %s", __entry->vcpu->cpu,

		  audit_point_name[__entry->audit_point])

);

#endif /* _TRACE_KVMMMU_H */



#undef TRACE_INCLUDE_PATH

arch/x86/kvm/paging_tmpl.h

+2 −2
Original line number Diff line number Diff line
@@ -542,7 +542,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
	if (mmu_notifier_retry(vcpu, mmu_seq))

		goto out_unlock;



	kvm_mmu_audit(vcpu, "pre page fault");

	trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);

	kvm_mmu_free_some_pages(vcpu);

	sptep = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,

			     level, &write_pt, pfn);
@@ -554,7 +554,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
		vcpu->arch.last_pt_write_count = 0; /* reset fork detector */



	++vcpu->stat.pf_fixed;

	kvm_mmu_audit(vcpu, "post page fault (fixed)");

	trace_kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);

	spin_unlock(&vcpu->kvm->mmu_lock);



	return write_pt;