On Intel platforms, software may uses IA32_MISC_ENABLE[7]
bit to detect whether the performance monitoring facility
is supported in the processor.
A write to this PMU available bit will be ignored.
Cc: Yao Yuan <[email protected]>
Signed-off-by: Like Xu <[email protected]>
---
arch/x86/kvm/vmx/pmu_intel.c | 2 ++
arch/x86/kvm/x86.c | 1 +
2 files changed, 3 insertions(+)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index a886a47daebd..01c7d84ecf3e 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -339,6 +339,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
if (!pmu->version)
return;
+ vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_EMON;
+
perf_get_x86_pmu_capability(&x86_pmu);
if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
vcpu->arch.perf_capabilities = vmx_get_perf_capabilities();
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c4015a43cc8a..d7b8f98ada93 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3042,6 +3042,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
}
break;
case MSR_IA32_MISC_ENABLE:
+ data &= ~MSR_IA32_MISC_ENABLE_EMON;
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT) &&
((vcpu->arch.ia32_misc_enable_msr ^ data) & MSR_IA32_MISC_ENABLE_MWAIT)) {
if (!guest_cpuid_has(vcpu, X86_FEATURE_XMM3))
--
2.21.3
On Intel platforms, KVM agent could configure MSR_IA32_PERF_CAPABILITIES
(such as unmask some vmx-supported bits in vcpu->arch.perf_capabilities)
to adjust the visibility of guest PMU features for vPMU-enabled guests.
Once MSR_IA32_PERF_CAPABILITIES is changed via vmx_set_msr() validly,
the adjustment in intel_pmu_refresh() will be triggered. To ensure the
sustainability of the new value, the default initialization path is
moved to intel_pmu_init().
Signed-off-by: Like Xu <[email protected]>
---
arch/x86/kvm/vmx/pmu_intel.c | 6 +++---
arch/x86/kvm/vmx/vmx.c | 5 +++++
arch/x86/kvm/x86.c | 2 +-
3 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 01c7d84ecf3e..7c18c85328da 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -327,7 +327,6 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
pmu->counter_bitmask[KVM_PMC_FIXED] = 0;
pmu->version = 0;
pmu->reserved_bits = 0xffffffff00200000ull;
- vcpu->arch.perf_capabilities = 0;
entry = kvm_find_cpuid_entry(vcpu, 0xa, 0);
if (!entry)
@@ -342,8 +341,6 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_EMON;
perf_get_x86_pmu_capability(&x86_pmu);
- if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
- vcpu->arch.perf_capabilities = vmx_get_perf_capabilities();
pmu->nr_arch_gp_counters = min_t(int, eax.split.num_counters,
x86_pmu.num_counters_gp);
@@ -403,6 +400,9 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu)
pmu->fixed_counters[i].idx = i + INTEL_PMC_IDX_FIXED;
pmu->fixed_counters[i].current_config = 0;
}
+
+ vcpu->arch.perf_capabilities = guest_cpuid_has(vcpu, X86_FEATURE_PDCM) ?
+ vmx_get_perf_capabilities() : 0;
}
static void intel_pmu_reset(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4551a7e80ebc..a3f3ce222af1 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2182,6 +2182,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if ((data >> 32) != 0)
return 1;
goto find_uret_msr;
+ case MSR_IA32_PERF_CAPABILITIES:
+ if (data && !vcpu_to_pmu(vcpu)->version)
+ return 1;
+ ret = kvm_set_msr_common(vcpu, msr_info);
+ break;
default:
find_uret_msr:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d7b8f98ada93..a525447a92c6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2985,7 +2985,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return 1;
vcpu->arch.perf_capabilities = data;
-
+ kvm_pmu_refresh(vcpu);
return 0;
}
case MSR_EFER:
--
2.21.3
Hi,
Is the community not interested in these two patches?
The second one also appears in the LBR patch set and
will benefit other PMU features later, such as PEBS.
Thanks,
Like Xu
On 2020/10/20 22:57, Like Xu wrote:
> On Intel platforms, software may uses IA32_MISC_ENABLE[7]
> bit to detect whether the performance monitoring facility
> is supported in the processor.
>
> A write to this PMU available bit will be ignored.
>
> Cc: Yao Yuan <[email protected]>
> Signed-off-by: Like Xu <[email protected]>
> ---
> arch/x86/kvm/vmx/pmu_intel.c | 2 ++
> arch/x86/kvm/x86.c | 1 +
> 2 files changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index a886a47daebd..01c7d84ecf3e 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -339,6 +339,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
> if (!pmu->version)
> return;
>
> + vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_EMON;
> +
> perf_get_x86_pmu_capability(&x86_pmu);
> if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
> vcpu->arch.perf_capabilities = vmx_get_perf_capabilities();
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c4015a43cc8a..d7b8f98ada93 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3042,6 +3042,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> }
> break;
> case MSR_IA32_MISC_ENABLE:
> + data &= ~MSR_IA32_MISC_ENABLE_EMON;
> if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT) &&
> ((vcpu->arch.ia32_misc_enable_msr ^ data) & MSR_IA32_MISC_ENABLE_MWAIT)) {
> if (!guest_cpuid_has(vcpu, X86_FEATURE_XMM3))
>