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Subject[RFC v1 9/9] KVM: x86: Expose PEBS feature to guest
Date
Expose PEBS feature to guest by IA32_MISC_ENABLE[bit12].
IA32_MISC_ENABLE[bit12] is Processor Event Based Sampling (PEBS)
Unavailable (RO) flag:
1 = PEBS is not supported; 0 = PEBS is supported.

Signed-off-by: Luwei Kang <luwei.kang@intel.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 6 ++++++
arch/x86/kvm/vmx/vmx.c | 1 +
arch/x86/kvm/x86.c | 22 +++++++++++++++++-----
4 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 94af338..f6a5630 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1130,6 +1130,7 @@ struct kvm_x86_ops {
bool (*xsaves_supported)(void);
bool (*umip_emulated)(void);
bool (*pt_supported)(void);
+ bool (*pebs_supported)(void);
bool (*pdcm_supported)(void);

int (*check_nested_events)(struct kvm_vcpu *vcpu, bool external_intr);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8ae6716..2b271fc 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6005,6 +6005,11 @@ static bool svm_pt_supported(void)
return false;
}

+static bool svm_pebs_supported(void)
+{
+ return false;
+}
+
static bool svm_pdcm_supported(void)
{
return false;
@@ -7298,6 +7303,7 @@ static bool svm_need_emulation_on_page_fault(struct kvm_vcpu *vcpu)
.xsaves_supported = svm_xsaves_supported,
.umip_emulated = svm_umip_emulated,
.pt_supported = svm_pt_supported,
+ .pebs_supported = svm_pebs_supported,
.pdcm_supported = svm_pdcm_supported,

.set_supported_cpuid = svm_set_supported_cpuid,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 71e3d42..d85f19b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7782,6 +7782,7 @@ static __exit void hardware_unsetup(void)
.xsaves_supported = vmx_xsaves_supported,
.umip_emulated = vmx_umip_emulated,
.pt_supported = vmx_pt_supported,
+ .pebs_supported = vmx_pebs_supported,
.pdcm_supported = vmx_pdcm_supported,

.request_immediate_exit = vmx_request_immediate_exit,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 290c3c3..8ad501d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2483,6 +2483,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
bool pr = false;
+ bool update_cpuid = false;
u32 msr = msr_info->index;
u64 data = msr_info->data;

@@ -2563,11 +2564,17 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
((vcpu->arch.ia32_misc_enable_msr ^ data) & MSR_IA32_MISC_ENABLE_MWAIT)) {
if (!guest_cpuid_has(vcpu, X86_FEATURE_XMM3))
return 1;
- vcpu->arch.ia32_misc_enable_msr = data;
- kvm_update_cpuid(vcpu);
- } else {
- vcpu->arch.ia32_misc_enable_msr = data;
+ update_cpuid = true;
}
+
+ if (kvm_x86_ops->pebs_supported())
+ data &= ~MSR_IA32_MISC_ENABLE_PEBS;
+ else
+ data |= MSR_IA32_MISC_ENABLE_PEBS;
+
+ vcpu->arch.ia32_misc_enable_msr = data;
+ if (update_cpuid)
+ kvm_update_cpuid(vcpu);
break;
case MSR_IA32_SMBASE:
if (!msr_info->host_initiated)
@@ -2875,7 +2882,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = (u64)vcpu->arch.ia32_tsc_adjust_msr;
break;
case MSR_IA32_MISC_ENABLE:
- msr_info->data = vcpu->arch.ia32_misc_enable_msr;
+ if (kvm_x86_ops->pebs_supported())
+ msr_info->data = (vcpu->arch.ia32_misc_enable_msr &
+ ~MSR_IA32_MISC_ENABLE_PEBS);
+ else
+ msr_info->data = (vcpu->arch.ia32_misc_enable_msr |
+ MSR_IA32_MISC_ENABLE_PEBS);
break;
case MSR_IA32_SMBASE:
if (!msr_info->host_initiated)
--
1.8.3.1
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