Messages in this thread | | | Subject | Re: [PATCH] KVM: X86: Allow userspace to define the microcode version | From | Paolo Bonzini <> | Date | Mon, 23 Apr 2018 18:03:40 +0200 |
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On 23/04/2018 14:58, Borislav Petkov wrote: >>>> 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). > Can't qemu do: > > grep microcode /proc/cpuinfo | awk '{ print $3 }' | head -n 1 > > ?
Yes, but you took that a statement bit too narrowly.
We didn't include KVM_GET_MSRS because microcode version wasn't otherwise available; rather, there's a general need for KVM userspace to know the values of host MSRs, and microcode is an example.
Paolo
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