Commit 2ca1a06a authored Apr 16, 2020 by Venkatesh Srinivas Committed by Paolo Bonzini Apr 17, 2020

kvm: Handle reads of SandyBridge RAPL PMU MSRs rather than injecting #GP

Linux 3.14 unconditionally reads the RAPL PMU MSRs on boot, without handling
General Protection Faults on reading those MSRs. Rather than injecting a #GP,
which prevents boot, handle the MSRs by returning 0 for their data. Zero was
checked to be safe by code review of the RAPL PMU driver and in discussion
with the original driver author (eranian@google.com).

Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
Signed-off-by: Jon Cargille <jcargill@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200416184254.248374-1-jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 7289fdb5

arch/x86/kvm/x86.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -3060,6 +3060,17 @@ int kvm_get_msr_common(struct kvm_vcpu vcpu, struct msr_data msr_info)
		case MSR_IA32_PERF_CTL:
		case MSR_AMD64_DC_CFG:
		case MSR_F15H_EX_CFG:
		/*
		* Intel Sandy Bridge CPUs must support the RAPL (running average power
		* limit) MSRs. Just return 0, as we do not want to expose the host
		* data here. Do not conditionalize this on CPUID, as KVM does not do
		* so for existing CPU-specific MSRs.
		*/
		case MSR_RAPL_POWER_UNIT:
		case MSR_PP0_ENERGY_STATUS: /* Power plane 0 (core) */
		case MSR_PP1_ENERGY_STATUS: /* Power plane 1 (graphics uncore) */
		case MSR_PKG_ENERGY_STATUS: /* Total package */
		case MSR_DRAM_ENERGY_STATUS: /* DRAM controller */
		msr_info->data = 0;
		break;
		case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5:

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