On Tue, Apr 17, 2018 at 06:40:58PM +0800, Wanpeng Li wrote: > Cc Eduardo, > 2018-02-26 20:41 GMT+08:00 Paolo Bonzini <pbonzini@xxxxxxxxxx>: > > 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. > > Hi Paolo, > > Do you mean the host admin to get the ucode_rev from the host and set > to -cpu host, ucode_rev=xxxxxx or qemu get the ucode_rev directly by > rdmsr? 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. -- Eduardo
