[PATCH v3 02/17] KVM: x86/pmu: Use IA32_PERF_CAPABILITIES to adjust features visibility

Like Xu
2021-01-04T13:24:05Z

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 validly via vmx_set_msr(),
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 <like.xu@linux.intel.com>
---
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 75c9c6a0a3a4..09bc41c53cd8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2196,6 +2196,11 @@ 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 87f97ffa9966..a38ca932eec5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3037,7 +3037,7 @@ 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:
--
2.29.2