2018-04-18 18:36 GMT+08:00 Paolo Bonzini <pbonzini@xxxxxxxxxx>: > On 18/04/2018 11:03, Eduardo Habkost wrote: >>>> QEMU setting ucode_rev automatically using the host value when >>>> using "-cpu host" (with no need for explicit ucode_rev option) >>>> makes sense to me. >>> QEMU can't get the host value by rdmsr MSR_IA32_UCODE_REV directly >>> since rdmsr will #GP when ring !=0, any idea? >> By looking at kvm_get_msr_feature(), it looks like >> ioctl(system_fd, KVM_GET_MSRS) would return the host MSR value >> for us. > > Yes, that's exactly what it was introduced for (together with other MSRs > including VMX capabilities). How about the live migration? What will happen if the source and destination machines have different microcode version? Regards, Wanpeng Li
