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

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Message-Id: <20221125040604.5051-15-weijiang.yang@intel.com>
Date:   Thu, 24 Nov 2022 23:06:03 -0500
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     seanjc@...gle.com, pbonzini@...hat.com, jmattson@...gle.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     like.xu.linux@...il.com, kan.liang@...ux.intel.com,
        wei.w.wang@...el.com, weijiang.yang@...el.com
Subject: [PATCH v2 14/15] KVM: x86: Add Arch LBR data MSR access interface

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@...el.com>
Reviewed-by: Kan Liang <kan.liang@...ux.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