[PATCH v4 05/12] KVM: x86/pmu: Error when user sets the GLOBAL_STATUS reserved bits

Like Xu
2023-02-14T05:08:46Z

From: Like Xu <likexu@tencent.com>

If the user space sets reserved bits when restoring the MSR_CORE_
PERF_GLOBAL_STATUS register, these bits will be accidentally returned
when the guest runs a read access to this register, and cannot be cleared
up inside the guest, which makes the guest's PMI handler very confused.

Signed-off-by: Like Xu <likexu@tencent.com>
---
arch/x86/kvm/vmx/pmu_intel.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 904f832fc55d..aaea25d2cae8 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -397,7 +397,7 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
reprogram_fixed_counters(pmu, data);
break;
case MSR_CORE_PERF_GLOBAL_STATUS:
- if (!msr_info->host_initiated)
+ if (!msr_info->host_initiated || (data & pmu->global_ovf_ctrl_mask))
return 1; /* RO MSR */

pmu->global_status = data;
--
2.39.1