On 4/22/2022 3:55 AM, Yang Weijiang wrote:
Arch LBR MSRs are xsave-supported, but they're operated as "independent"
xsave feature by PMU code, i.e., during thread/process context switch,
the MSRs are saved/restored with PMU specific code instead of generic
kernel fpu XSAVES/XRSTORS operation.
During thread/process context switch, Linux perf still uses the
XSAVES/XRSTORS operation to save/restore the LBR MSRs.
Linux perf only manipulates these MSRs only when the xsave feature is
not supported.
Thanks,
Kan
When vcpu guest/host fpu state swap
happens, Arch LBR MSRs won't be touched so access them directly.
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
arch/x86/kvm/vmx/pmu_intel.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 79eecbffa07b..5f81644c4612 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -431,6 +431,11 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_ARCH_LBR_CTL:
msr_info->data = vmcs_read64(GUEST_IA32_LBR_CTL);
return 0;
+ case MSR_ARCH_LBR_FROM_0 ... MSR_ARCH_LBR_FROM_0 + 31:
+ case MSR_ARCH_LBR_TO_0 ... MSR_ARCH_LBR_TO_0 + 31:
+ case MSR_ARCH_LBR_INFO_0 ... MSR_ARCH_LBR_INFO_0 + 31:
+ rdmsrl(msr_info->index, msr_info->data);
+ return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
@@ -512,6 +517,11 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
(data & ARCH_LBR_CTL_LBREN))
intel_pmu_create_guest_lbr_event(vcpu);
return 0;
+ case MSR_ARCH_LBR_FROM_0 ... MSR_ARCH_LBR_FROM_0 + 31:
+ case MSR_ARCH_LBR_TO_0 ... MSR_ARCH_LBR_TO_0 + 31:
+ case MSR_ARCH_LBR_INFO_0 ... MSR_ARCH_LBR_INFO_0 + 31:
+ wrmsrl(msr_info->index, msr_info->data);
+ return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
