On 26/02/2018 13:22, Borislav Petkov wrote: > On Mon, Feb 26, 2018 at 01:18:07PM +0100, Paolo Bonzini wrote: >>> In this context, "host-initiated" write means written by KVM userspace >>> with ioctl(KVM_SET_MSR). It generally happens only on VM startup, reset >>> or live migration. >> >> To be clear, the target of the write is still the vCPU's emulated MSR. > > So how am I to imagine this as a user: > > qemu-system-x86_64 --microcode-revision=0xdeadbeef... More like "-cpu foo,ucode_rev=0xdeadbeef". But in practice what would happen is one of the following: 1) "-cpu host" sets ucode_rev to the same value of the host, everyone else leaves it to zero as is now. 2) Only Amazon uses this feature and we ignore it. :) Paolo
