Re: [PATCH 2/4] kvm: Allow invtsc migration if tsc-khz is set explicitly

Marcelo Tosatti
2017-01-04T11:57:40Z

On Wed, Jan 04, 2017 at 09:44:06AM -0200, Marcelo Tosatti wrote:
> On Tue, Dec 27, 2016 at 05:21:18PM -0200, Eduardo Habkost wrote:
> > We can safely allow a VM to be migrated with invtsc enabled if
> > tsc-khz is set explicitly, because QEMU already refuses to start
> > if it can't set the TSC frequency to the configured value.
>
> On the source host, yes, but on the destination it does not.
>
> SOURCE: -cpu kvm64,tsc-frequency=2660001000
> DESTINATION: -cpu kvm64
>
> Only prints:
>
> qemu-system-x86_64: warning: TSC frequency mismatch between VM (2660001
> kHz) and host (2893428 kHz), and TSC scaling unavailable
> qemu-system-x86_64: warning: TSC frequency mismatch between VM (2660001
> kHz) and host (2893428 kHz), and TSC scaling unavailable
>
> And allows migration.

Ignore that comment, patch 4 deals with it.