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

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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>
This commit is contained in:
Venkatesh Srinivas 2020-04-16 11:42:54 -07:00 committed by Paolo Bonzini
parent 7289fdb5dc
commit 2ca1a06a54
1 changed files with 11 additions and 0 deletions
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11
arch/x86/kvm/x86.c
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@ -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: