* [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events
@ 2020-12-23 14:45 Dario Faggioli
2021-01-16 1:25 ` Dario Faggioli
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Dario Faggioli @ 2020-12-23 14:45 UTC (permalink / raw)
To: linux-kernel
Cc: Lorenzo Brescia, Paolo Bonzini, Sean Christopherson,
Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
Lorenzo Brescia
From: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
On VMX, if we exit and then re-enter immediately without leaving
the vmx_vcpu_run() function, the kvm_entry event is not logged.
That means we will see one (or more) kvm_exit, without its (their)
corresponding kvm_entry, as shown here:
CPU-1979 [002] 89.871187: kvm_entry: vcpu 1
CPU-1979 [002] 89.871218: kvm_exit: reason MSR_WRITE
CPU-1979 [002] 89.871259: kvm_exit: reason MSR_WRITE
It also seems possible for a kvm_entry event to be logged, but then
we leave vmx_vcpu_run() right away (if vmx->emulation_required is
true). In this case, we will have a spurious kvm_entry event in the
trace.
Fix these situations by moving trace_kvm_entry() inside vmx_vcpu_run()
(where trace_kvm_exit() already is).
A trace obtained with this patch applied looks like this:
CPU-14295 [000] 8388.395387: kvm_entry: vcpu 0
CPU-14295 [000] 8388.395392: kvm_exit: reason MSR_WRITE
CPU-14295 [000] 8388.395393: kvm_entry: vcpu 0
CPU-14295 [000] 8388.395503: kvm_exit: reason EXTERNAL_INTERRUPT
Of course, not calling trace_kvm_entry() in common x86 code any
longer means that we need to adjust the SVM side of things too.
Signed-off-by: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
---
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: kvm@vger.kernel.org
Cc: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
Cc: Dario Faggioli <dfaggioli@suse.com>
---
arch/x86/kvm/svm/svm.c | 2 ++
arch/x86/kvm/vmx/vmx.c | 2 ++
arch/x86/kvm/x86.c | 3 +--
3 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index cce0143a6f80..ed272fcf6495 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3741,6 +3741,8 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
+ trace_kvm_entry(vcpu);
+
svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
svm->vmcb->save.rip = vcpu->arch.regs[VCPU_REGS_RIP];
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 75c9c6a0a3a4..ff20f9e6e5b3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6653,6 +6653,8 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (vmx->emulation_required)
return EXIT_FASTPATH_NONE;
+ trace_kvm_entry(vcpu);
+
if (vmx->ple_window_dirty) {
vmx->ple_window_dirty = false;
vmcs_write32(PLE_WINDOW, vmx->ple_window);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3f7c1fc7a3ce..a79666204907 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8973,8 +8973,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_x86_ops.request_immediate_exit(vcpu);
}
- trace_kvm_entry(vcpu);
-
fpregs_assert_state_consistent();
if (test_thread_flag(TIF_NEED_FPU_LOAD))
switch_fpu_return();
@@ -11538,6 +11536,7 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
}
EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
+EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events
2020-12-23 14:45 [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events Dario Faggioli
@ 2021-01-16 1:25 ` Dario Faggioli
2021-01-18 18:20 ` Paolo Bonzini
2021-01-21 14:55 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Dario Faggioli @ 2021-01-16 1:25 UTC (permalink / raw)
To: linux-kernel
Cc: Lorenzo Brescia, Paolo Bonzini, Sean Christopherson,
Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm
[-- Attachment #1: Type: text/plain, Size: 1082 bytes --]
On Wed, 2020-12-23 at 14:45 +0000, Dario Faggioli wrote:
> From: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
>
> On VMX, if we exit and then re-enter immediately without leaving
> the vmx_vcpu_run() function, the kvm_entry event is not logged.
> That means we will see one (or more) kvm_exit, without its (their)
> corresponding kvm_entry, as shown here:
>
> CPU-1979 [002] 89.871187: kvm_entry: vcpu 1
> CPU-1979 [002] 89.871218: kvm_exit: reason MSR_WRITE
> CPU-1979 [002] 89.871259: kvm_exit: reason MSR_WRITE
>
> It also seems possible for a kvm_entry event to be logged, but then
> we leave vmx_vcpu_run() right away (if vmx->emulation_required is
> true). In this case, we will have a spurious kvm_entry event in the
> trace.
>
Gentle ping... :-)
Thanks and Regards
--
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
-------------------------------------------------------------------
<<This happens because _I_ choose it to happen!>> (Raistlin Majere)
[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events
2020-12-23 14:45 [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events Dario Faggioli
2021-01-16 1:25 ` Dario Faggioli
@ 2021-01-18 18:20 ` Paolo Bonzini
2021-01-21 14:55 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2021-01-18 18:20 UTC (permalink / raw)
To: Dario Faggioli, linux-kernel
Cc: Lorenzo Brescia, Sean Christopherson, Vitaly Kuznetsov,
Wanpeng Li, Jim Mattson, Joerg Roedel, kvm
On 23/12/20 15:45, Dario Faggioli wrote:
> From: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
>
> On VMX, if we exit and then re-enter immediately without leaving
> the vmx_vcpu_run() function, the kvm_entry event is not logged.
> That means we will see one (or more) kvm_exit, without its (their)
> corresponding kvm_entry, as shown here:
>
> CPU-1979 [002] 89.871187: kvm_entry: vcpu 1
> CPU-1979 [002] 89.871218: kvm_exit: reason MSR_WRITE
> CPU-1979 [002] 89.871259: kvm_exit: reason MSR_WRITE
>
> It also seems possible for a kvm_entry event to be logged, but then
> we leave vmx_vcpu_run() right away (if vmx->emulation_required is
> true). In this case, we will have a spurious kvm_entry event in the
> trace.
>
> Fix these situations by moving trace_kvm_entry() inside vmx_vcpu_run()
> (where trace_kvm_exit() already is).
>
> A trace obtained with this patch applied looks like this:
>
> CPU-14295 [000] 8388.395387: kvm_entry: vcpu 0
> CPU-14295 [000] 8388.395392: kvm_exit: reason MSR_WRITE
> CPU-14295 [000] 8388.395393: kvm_entry: vcpu 0
> CPU-14295 [000] 8388.395503: kvm_exit: reason EXTERNAL_INTERRUPT
>
> Of course, not calling trace_kvm_entry() in common x86 code any
> longer means that we need to adjust the SVM side of things too.
>
> Signed-off-by: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
> Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
> ---
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Sean Christopherson <seanjc@google.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Wanpeng Li <wanpengli@tencent.com>
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: kvm@vger.kernel.org
> Cc: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
> Cc: Dario Faggioli <dfaggioli@suse.com>
> ---
> arch/x86/kvm/svm/svm.c | 2 ++
> arch/x86/kvm/vmx/vmx.c | 2 ++
> arch/x86/kvm/x86.c | 3 +--
> 3 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index cce0143a6f80..ed272fcf6495 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3741,6 +3741,8 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
> {
> struct vcpu_svm *svm = to_svm(vcpu);
>
> + trace_kvm_entry(vcpu);
> +
> svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
> svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
> svm->vmcb->save.rip = vcpu->arch.regs[VCPU_REGS_RIP];
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 75c9c6a0a3a4..ff20f9e6e5b3 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6653,6 +6653,8 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
> if (vmx->emulation_required)
> return EXIT_FASTPATH_NONE;
>
> + trace_kvm_entry(vcpu);
> +
> if (vmx->ple_window_dirty) {
> vmx->ple_window_dirty = false;
> vmcs_write32(PLE_WINDOW, vmx->ple_window);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3f7c1fc7a3ce..a79666204907 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8973,8 +8973,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> kvm_x86_ops.request_immediate_exit(vcpu);
> }
>
> - trace_kvm_entry(vcpu);
> -
> fpregs_assert_state_consistent();
> if (test_thread_flag(TIF_NEED_FPU_LOAD))
> switch_fpu_return();
> @@ -11538,6 +11536,7 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
> }
> EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
>
> +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
>
>
Qeuued, thanks!
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events
2020-12-23 14:45 [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events Dario Faggioli
2021-01-16 1:25 ` Dario Faggioli
2021-01-18 18:20 ` Paolo Bonzini
@ 2021-01-21 14:55 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2021-01-21 14:55 UTC (permalink / raw)
To: Dario Faggioli, linux-kernel
Cc: Lorenzo Brescia, Sean Christopherson, Vitaly Kuznetsov,
Wanpeng Li, Jim Mattson, Joerg Roedel, kvm
On 23/12/20 15:45, Dario Faggioli wrote:
> From: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
>
> On VMX, if we exit and then re-enter immediately without leaving
> the vmx_vcpu_run() function, the kvm_entry event is not logged.
> That means we will see one (or more) kvm_exit, without its (their)
> corresponding kvm_entry, as shown here:
>
> CPU-1979 [002] 89.871187: kvm_entry: vcpu 1
> CPU-1979 [002] 89.871218: kvm_exit: reason MSR_WRITE
> CPU-1979 [002] 89.871259: kvm_exit: reason MSR_WRITE
>
> It also seems possible for a kvm_entry event to be logged, but then
> we leave vmx_vcpu_run() right away (if vmx->emulation_required is
> true). In this case, we will have a spurious kvm_entry event in the
> trace.
>
> Fix these situations by moving trace_kvm_entry() inside vmx_vcpu_run()
> (where trace_kvm_exit() already is).
>
> A trace obtained with this patch applied looks like this:
>
> CPU-14295 [000] 8388.395387: kvm_entry: vcpu 0
> CPU-14295 [000] 8388.395392: kvm_exit: reason MSR_WRITE
> CPU-14295 [000] 8388.395393: kvm_entry: vcpu 0
> CPU-14295 [000] 8388.395503: kvm_exit: reason EXTERNAL_INTERRUPT
>
> Of course, not calling trace_kvm_entry() in common x86 code any
> longer means that we need to adjust the SVM side of things too.
>
> Signed-off-by: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
> Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
> ---
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Sean Christopherson <seanjc@google.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Wanpeng Li <wanpengli@tencent.com>
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: kvm@vger.kernel.org
> Cc: Lorenzo Brescia <lorenzo.brescia@edu.unito.it>
> Cc: Dario Faggioli <dfaggioli@suse.com>
> ---
> arch/x86/kvm/svm/svm.c | 2 ++
> arch/x86/kvm/vmx/vmx.c | 2 ++
> arch/x86/kvm/x86.c | 3 +--
> 3 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index cce0143a6f80..ed272fcf6495 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3741,6 +3741,8 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
> {
> struct vcpu_svm *svm = to_svm(vcpu);
>
> + trace_kvm_entry(vcpu);
> +
> svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
> svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
> svm->vmcb->save.rip = vcpu->arch.regs[VCPU_REGS_RIP];
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 75c9c6a0a3a4..ff20f9e6e5b3 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6653,6 +6653,8 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
> if (vmx->emulation_required)
> return EXIT_FASTPATH_NONE;
>
> + trace_kvm_entry(vcpu);
> +
> if (vmx->ple_window_dirty) {
> vmx->ple_window_dirty = false;
> vmcs_write32(PLE_WINDOW, vmx->ple_window);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3f7c1fc7a3ce..a79666204907 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8973,8 +8973,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> kvm_x86_ops.request_immediate_exit(vcpu);
> }
>
> - trace_kvm_entry(vcpu);
> -
> fpregs_assert_state_consistent();
> if (test_thread_flag(TIF_NEED_FPU_LOAD))
> switch_fpu_return();
> @@ -11538,6 +11536,7 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
> }
> EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
>
> +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
>
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-01-21 14:58 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-12-23 14:45 [PATCH] kvm: tracing: Fix unmatched kvm_entry and kvm_exit events Dario Faggioli
2021-01-16 1:25 ` Dario Faggioli
2021-01-18 18:20 ` Paolo Bonzini
2021-01-21 14:55 ` Paolo Bonzini
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