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Re: [Qemu-devel] -cpu check, rdtscp and AMD KVM
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From: |
Eduardo Habkost |
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Subject: |
Re: [Qemu-devel] -cpu check, rdtscp and AMD KVM |
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Date: |
Thu, 12 Nov 2015 14:27:48 -0200 |
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User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Thu, Nov 12, 2015 at 04:58:37PM +0100, Paolo Bonzini wrote:
> On 12/11/2015 16:25, Eduardo Habkost wrote:
> > On Thu, Nov 12, 2015 at 11:53:44AM +0100, Paolo Bonzini wrote:
> >> Eduardo,
> >>
> >> running QEMU 2.5 on SVM causes a warning because rdtscp is not supported
> >> by KVM. While I can fix it, that leaves a warning on all existing kernels.
> >
> > You mean when using Opteron_G2 or newer, right? qemu64 and kvm64
> > don't have rdtscp enabled.
> >
> >> What do you think is the best way forward?
> >
> > To simply remove rdtscp from all Opteron_G* models?
>
> Not sure this is the right thing to do... Real hardware has it, and
> going forward KVM will provide it.
Do you see any alternative? We need AMD CPU models that can run
out of the box using today's kernels. As no existing VMs running
Opteron_G* on AMD CPUs have rdtscp, I believe it makes sense to
just define Opteron_G* without rdtscp.
When we add SVM rdtscp support to KVM, we can add new
"Opteron_G[2-5]-rdtscp" CPU models.
--
Eduardo