'Unhandled wrmsr' or 'unhandled rdmsr' log messages on KVM/RHEV hypervisors

Solution Verified - Updated -

Issue

  • Messages in the following format appear in hypervisor logs:

    kvm: <thread tgid>: cpu<vcpu number> unhandled wrmsr: <model specific register> data <value>
    
  • Example output:

    kvm: 4734: cpu0 unhandled wrmsr: 0x198 data 0
    kvm: 4734: cpu1 unhandled wrmsr: 0x198 data 0
    kvm: 4734: cpu2 unhandled wrmsr: 0x198 data 0
    kvm: 4734: cpu3 unhandled wrmsr: 0x198 data 0
    
  • There are no errors on guests. No other symptoms are present:

    kvm: 661: cpu1 unhandled wrmsr: 0x391 data 2000000f
    kvm: 661: cpu0 unhandled wrmsr: 0x391 data 2000000f
    
  • What does this message mean?

    kernel: kvm: 23772: cpu0 unhandled rdmsr: 0x19a
    

Environment

  • Red Hat Enterprise Virtualization
  • Red Hat Enterprise Linux 5 with KVM Virtualization
  • Red Hat Enterprise Linux 6 with KVM Virtualization
  • Red Hat Enterprise Linux 7 with KVM Virtualization

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