Userspace could enable guest LBR feature when the exactly supported
LBR format value is initialized to the MSR_IA32_PERF_CAPABILITIES
and the LBR is also compatible with vPMU version and host cpu model.
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/capabilities.h | 9 ++++++++-
arch/x86/kvm/vmx/vmx.c | 10 ++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index f17ab6cf152e..5829f4e9a7e0 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -378,7 +378,14 @@ static inline u64 vmx_get_perf_capabilities(void)
* Since counters are virtualized, KVM would support full
* width counting unconditionally, even if the host lacks it.
*/
- return PMU_CAP_FW_WRITES;
+ u64 perf_cap = PMU_CAP_FW_WRITES;
+
+ if (boot_cpu_has(X86_FEATURE_PDCM))
+ rdmsrl(MSR_IA32_PERF_CAPABILITIES, perf_cap);
+
+ perf_cap |= perf_cap & PMU_CAP_LBR_FMT;
+
+ return perf_cap;
}
static inline u64 vmx_supported_debugctl(void)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b72fbbef56fa..6d8b1d98ae1d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2251,6 +2251,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if ((data >> 32) != 0)
return 1;
goto find_shared_msr;
+ case MSR_IA32_PERF_CAPABILITIES:
+ if (data & PMU_CAP_LBR_FMT) {
+ if ((data & PMU_CAP_LBR_FMT) !=
+ (vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT))
+ return 1;
+ if (!intel_pmu_lbr_is_compatible(vcpu))
+ return 1;
+ }
+ ret = kvm_set_msr_common(vcpu, msr_info);
+ break;
default:
find_shared_msr:
--
2.21.3
