From 5a329907b3926edb3917b21d5cfef3ba653ff52c Mon Sep 17 00:00:00 2001 From: Marios Pomonis Date: Wed, 11 Dec 2019 12:47:48 -0800 Subject: [PATCH] KVM: x86: Protect MSR-based index computations in pmu.h from Spectre-v1/L1TF attacks commit 13c5183a4e643cc2b03a22d0e582c8e17bb7457d upstream. This fixes a Spectre-v1/L1TF vulnerability in the get_gp_pmc() and get_fixed_pmc() functions. They both contain index computations based on the (attacker-controlled) MSR number. Fixes: 25462f7f5295 ("KVM: x86/vPMU: Define kvm_pmu_ops to support vPMU function dispatch") Signed-off-by: Nick Finco Signed-off-by: Marios Pomonis Reviewed-by: Andrew Honig Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/pmu.h | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h index f96e1f962587..fbf3d25af765 100644 --- a/arch/x86/kvm/pmu.h +++ b/arch/x86/kvm/pmu.h @@ -1,6 +1,8 @@ #ifndef __KVM_X86_PMU_H #define __KVM_X86_PMU_H +#include + #define vcpu_to_pmu(vcpu) (&(vcpu)->arch.pmu) #define pmu_to_vcpu(pmu) (container_of((pmu), struct kvm_vcpu, arch.pmu)) #define pmc_to_pmu(pmc) (&(pmc)->vcpu->arch.pmu) @@ -80,8 +82,12 @@ static inline bool pmc_is_enabled(struct kvm_pmc *pmc) static inline struct kvm_pmc *get_gp_pmc(struct kvm_pmu *pmu, u32 msr, u32 base) { - if (msr >= base && msr < base + pmu->nr_arch_gp_counters) - return &pmu->gp_counters[msr - base]; + if (msr >= base && msr < base + pmu->nr_arch_gp_counters) { + u32 index = array_index_nospec(msr - base, + pmu->nr_arch_gp_counters); + + return &pmu->gp_counters[index]; + } return NULL; } @@ -91,8 +97,12 @@ static inline struct kvm_pmc *get_fixed_pmc(struct kvm_pmu *pmu, u32 msr) { int base = MSR_CORE_PERF_FIXED_CTR0; - if (msr >= base && msr < base + pmu->nr_arch_fixed_counters) - return &pmu->fixed_counters[msr - base]; + if (msr >= base && msr < base + pmu->nr_arch_fixed_counters) { + u32 index = array_index_nospec(msr - base, + pmu->nr_arch_fixed_counters); + + return &pmu->fixed_counters[index]; + } return NULL; } -- 2.11.0