Re: About MONITOR/MWAIT in i386 CPU model

[Eduardo Habkost]

On Wed, Nov 13, 2019 at 04:42:25PM +0800, Tao Xu wrote:
> Hi Eduardo，
> 
> After kvm use "-overcommit cpu-pm=on" to expose MONITOR/MWAIT
> (commit id 6f131f13e68d648a8e4f083c667ab1acd88ce4cd), the MONITOR/MWAIT
> feature in CPU model (phenom core2duo coreduo n270 Opteron_G3 EPYC Snowridge
> Denverton) may be unused. For example, when we boot a guest with Denverton
> cpu model, guest cannot detect MONITOR and boot with no warning. Should we
> remove this feature from some CPU model?

Good catch, thanks!

Yes, we should remove them from Opteron_G3, EPYC, Snowridge, and
Denverton, at least.  The other older CPU models can be left
alone: they are more useful for use with TCG than with KVM, and
TCG supports MONITOR/MWAIT.

I would like to understand why this wasn't detected during
testing by Intel.  I suggest always testing CPU models using the
"enforce" flag to make sure warnings don't go unnoticed.

> 
> Tested by Guo, Xuelian <address@hidden>
> 
> Tao Xu
> 

-- 
Eduardo