On Tue, Mar 23, 2021 at 4:48 PM Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote: > > MSR_F15H_PERF_CTL0-5, MSR_F15H_PERF_CTR0-5 MSRs are only available when > X86_FEATURE_PERFCTR_CORE CPUID bit was exposed to the guest. KVM, however, > allows these MSRs unconditionally because kvm_pmu_is_valid_msr() -> > amd_msr_idx_to_pmc() check always passes and because kvm_pmu_set_msr() -> > amd_pmu_set_msr() doesn't fail. I have tested on AMD EPYC platform with perfctr_core(`cat /proc/cpuinfo | grep perfctr_core`). I started a vm without `perfctr-core`(-cpu host,-perfctr-core). Before patch : $ rdmsr 0xc0010200 0 $ wrmsr 0xc0010200 1 $ rdmsr 0xc0010200 1 After patch: # rdmsr 0xc0010200 0 # wrmsr 0xc0010200 1 wrmsr: CPU 0 cannot set MSR 0xc0010200 to 0x0000000000000001 # rdmsr 0xc0010200 0 So, Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx>
