[PATCH v2 1/5] KVM: MMU: support disable/enable mmu audit dynamicly

Xiao Guangrong
2010-08-30T10:18:39Z

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

V2:
Using r/w module parameter instead of debugfs file

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/Kconfig | 7 +++
arch/x86/kvm/mmu.c | 91 +++++++++++++++++++++++++++++++++++---------
arch/x86/kvm/mmutrace.h | 19 +++++++++
arch/x86/kvm/paging_tmpl.h | 4 +-
4 files changed, 101 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 970bbd4..ddc131f 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -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
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 0bff4d5..8b750ff 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -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
diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
index 3aab0f0..b60b4fd 100644
--- a/arch/x86/kvm/mmutrace.h
+++ b/arch/x86/kvm/mmutrace.h
@@ -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
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index a0f2feb..debe770 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -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;
--
1.7.0.4