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Date: Tue, 29 Nov 2011 11:56:00 +0800
From: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
To: Jason Baron <jbaron@...hat.com>
CC: Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>,
LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH 2/5] KVM: MMU: audit: replace mmu audit tracepoint with
jump-lable
On 11/29/2011 06:33 AM, Jason Baron wrote:
> hmmm..this always going to do a call to 'kvm_mmu_audit' and then return.
> I think you want to avoid the function call altogether. You could do
> something like:
>
> #define kvm_mmu_audit()
> if (static_branch((&mmu_audit_key))) {
> __kvm_mmu_audit();
> }
>
> and s/kvm_mmu_audit/__kvm_mmu_audit
>
> That should give you a single nop for the case where kvm_mmu_audit is
> disabled instead of a function call.
Good point, thanks Jason!
Avi, could you please apply the following patch instead?
Subject: [PATCH v2 2/5] KVM: MMU: audit: replace mmu audit tracepoint with jump-lable
The tracepoint is only used to audit mmu code, it should not be exposed to
user, let us replace it with jump-lable
Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
---
arch/x86/kvm/mmu.c | 23 ++++++++++++-----------
arch/x86/kvm/mmu_audit.c | 17 +++++++++--------
arch/x86/kvm/mmutrace.h | 19 -------------------
arch/x86/kvm/paging_tmpl.h | 4 ++--
4 files changed, 23 insertions(+), 40 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index d737443..34bc3fc 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2840,6 +2840,13 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
return mmu_alloc_shadow_roots(vcpu);
}
+#ifdef CONFIG_KVM_MMU_AUDIT
+#include "mmu_audit.c"
+#else
+static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { }
+static void mmu_audit_disable(void) { }
+#endif
+
static void mmu_sync_roots(struct kvm_vcpu *vcpu)
{
int i;
@@ -2852,12 +2859,12 @@ static void mmu_sync_roots(struct kvm_vcpu *vcpu)
return;
vcpu_clear_mmio_info(vcpu, ~0ul);
- trace_kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
+ kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
sp = page_header(root);
mmu_sync_children(vcpu, sp);
- trace_kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
+ kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
return;
}
for (i = 0; i < 4; ++i) {
@@ -2869,7 +2876,7 @@ static void mmu_sync_roots(struct kvm_vcpu *vcpu)
mmu_sync_children(vcpu, sp);
}
}
- trace_kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
+ kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
}
void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
@@ -3667,7 +3674,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
spin_lock(&vcpu->kvm->mmu_lock);
++vcpu->kvm->stat.mmu_pte_write;
- trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);
+ kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);
mask.cr0_wp = mask.cr4_pae = mask.nxe = 1;
for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn, node) {
@@ -3700,7 +3707,7 @@ 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);
- trace_kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE);
+ kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE);
spin_unlock(&vcpu->kvm->mmu_lock);
}
@@ -4030,12 +4037,6 @@ void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
mmu_free_memory_caches(vcpu);
}
-#ifdef CONFIG_KVM_MMU_AUDIT
-#include "mmu_audit.c"
-#else
-static void mmu_audit_disable(void) { }
-#endif
-
void kvm_mmu_module_exit(void)
{
mmu_destroy_caches();
diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c
index 746ec25..967a535 100644
--- a/arch/x86/kvm/mmu_audit.c
+++ b/arch/x86/kvm/mmu_audit.c
@@ -224,7 +224,7 @@ 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 void __kvm_mmu_audit(struct kvm_vcpu *vcpu, int point)
{
static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
@@ -237,17 +237,19 @@ static void kvm_mmu_audit(void *ignore, struct kvm_vcpu *vcpu, int point)
}
static bool mmu_audit;
+static struct jump_label_key mmu_audit_key;
+
+#define kvm_mmu_audit(vcpu, point) \
+ if (static_branch((&mmu_audit_key))) { \
+ __kvm_mmu_audit(vcpu, point); \
+ }
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);
-
+ jump_label_inc(&mmu_audit_key);
mmu_audit = true;
}
@@ -256,8 +258,7 @@ static void mmu_audit_disable(void)
if (!mmu_audit)
return;
- unregister_trace_kvm_mmu_audit(kvm_mmu_audit, NULL);
- tracepoint_synchronize_unregister();
+ jump_label_dec(&mmu_audit_key);
mmu_audit = false;
}
diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
index eed67f3..89fb0e8 100644
--- a/arch/x86/kvm/mmutrace.h
+++ b/arch/x86/kvm/mmutrace.h
@@ -243,25 +243,6 @@ TRACE_EVENT(
TP_printk("addr:%llx gfn %llx access %x", __entry->addr, __entry->gfn,
__entry->access)
);
-
-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 52e9d58..1561028 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -632,7 +632,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
if (mmu_notifier_retry(vcpu, mmu_seq))
goto out_unlock;
- trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);
+ kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);
kvm_mmu_free_some_pages(vcpu);
if (!force_pt_level)
transparent_hugepage_adjust(vcpu, &walker.gfn, &pfn, &level);
@@ -643,7 +643,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
sptep, *sptep, emulate);
++vcpu->stat.pf_fixed;
- trace_kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
+ kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
spin_unlock(&vcpu->kvm->mmu_lock);
return emulate;
--
1.7.7.3
--
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