linux-kernel - [PATCH 2/3] KVM: x86: Ignore host accesses to higher version PMU features MSRs

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Message-Id: <20221226111710.51831-3-likexu@tencent.com>
Date:   Mon, 26 Dec 2022 19:17:09 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] KVM: x86: Ignore host accesses to higher version PMU features MSRs

From: Like Xu <likexu@...cent.com>

Higher version PMU features are obviously not supported on hosts with
lower version Arch pmu, such as trying to access FIXED_CTR registers
and PERF_GLOBAL registers from pmu.version >1 on a host with version 1.

Ignore host userspace reads and writes of '0' to those PMU MSRs that
KVM reports in the MSR-to-save list, but the MSRs are ultimately
unsupported. All MSRs in said list must be writable by userspace, e.g.
if userspace sends the list back at KVM without filtering out the MSRs
it doesn't need.

Signed-off-by: Like Xu <likexu@...cent.com>
---
 arch/x86/kvm/x86.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f570367463c8..fcb9c317df59 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3881,6 +3881,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_IA32_DS_AREA:
 	case MSR_PEBS_DATA_CFG:
 	case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5:
+	case MSR_ARCH_PERFMON_FIXED_CTR0 ... MSR_ARCH_PERFMON_FIXED_CTR_MAX:
+	case MSR_CORE_PERF_FIXED_CTR_CTRL:
+	case MSR_CORE_PERF_GLOBAL_STATUS:
+	case MSR_CORE_PERF_GLOBAL_CTRL:
+	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
 		if (kvm_pmu_is_valid_msr(vcpu, msr))
 			return kvm_pmu_set_msr(vcpu, msr_info);
 		/*
@@ -3984,6 +3989,11 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_IA32_DS_AREA:
 	case MSR_PEBS_DATA_CFG:
 	case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5:
+	case MSR_ARCH_PERFMON_FIXED_CTR0 ... MSR_ARCH_PERFMON_FIXED_CTR_MAX:
+	case MSR_CORE_PERF_FIXED_CTR_CTRL:
+	case MSR_CORE_PERF_GLOBAL_STATUS:
+	case MSR_CORE_PERF_GLOBAL_CTRL:
+	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
 		if (kvm_pmu_is_valid_msr(vcpu, msr_info->index))
 			return kvm_pmu_get_msr(vcpu, msr_info);
 		/*
-- 
2.39.0