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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 <likexu@tencent.com>
[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 <seanjc@google.com>
This commit is contained in:
Like Xu 2023-06-02 18:10:49 -07:00 committed by Sean Christopherson
parent 8de18543df
commit 30dab5c0b6
1 changed files with 3 additions and 0 deletions
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arch/x86/kvm/vmx/pmu_intel.c
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@ -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: