From: Like Xu Date: Sat, 3 Jun 2023 01:10:49 +0000 (-0700) Subject: KVM: x86/pmu: Reject userspace attempts to set reserved GLOBAL_STATUS bits X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=30dab5c0b65ea580878f36d6ae7ff85f06813387;p=linux.git KVM: x86/pmu: Reject userspace attempts to set reserved GLOBAL_STATUS bits Reject userspace writes to MSR_CORE_PERF_GLOBAL_STATUS that attempt to set reserved bits. Allowing userspace to stuff reserved bits doesn't harm KVM itself, but it's architecturally wrong and the guest can't clear the unsupported bits, e.g. makes the guest's PMI handler very confused. Signed-off-by: Like Xu [sean: rewrite changelog to avoid use of #GP, rebase on name change] Link: https://lore.kernel.org/r/20230603011058.1038821-4-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index edcf8670eb4ed..efd113f24c1b4 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -402,6 +402,9 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) if (!msr_info->host_initiated) return 1; /* RO MSR */ + if (data & pmu->global_status_mask) + return 1; + pmu->global_status = data; break; case MSR_CORE_PERF_GLOBAL_CTRL: