[PATCH v2 14/15] KVM: x86: Add Arch LBR data MSR access interface

Yang Weijiang
2022-11-25T06:10:35Z

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 perf_event_task_sched_{in|out} instead
of generic kernel fpu switch code, i.e.,save_fpregs_to_fpstate() and
restore_fpregs_from_fpstate(). When vcpu guest/host fpu state swap happens,
Arch LBR MSRs are retained so they can be accessed directly.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
---
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 b57944d5e7d8..241128972776 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -410,6 +410,11 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
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))) {
@@ -528,6 +533,11 @@ 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))) {
--
2.27.0