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). Paolo
