Re: [Xen-devel] XSA-60 - how to get back to a sane state

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Jan Beulich wrote:
>>>> On 03.12.13 at 04:06, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
>> I also vote option 2, but only revert 86d60e85, keeping 62652c00
>> (wbinvd at vmx_ctxt_switch_to) since it's used to avoid being
>> polluted when vcpu migrate to another cpu.
> 
> Please explain this in more detail. Both Andrew and I are concerned
> about this extra, but pretty pointless (without being done so too in
> other cases) wbinvd(). In particular you'd have to explain what its
> counterpart was in the code prior to your four patch XSA-60 series.
> 
> Jan

The wbinvd at vmx_ctxt_switch_to is for case like
1. vcpu runs at cpu A, flushing cache at vmx_handle_cd;
2. then the vcpu may switch out and migrate to cpu B;
3. historically cpu B may has cacheline polluted;
so when the vcpu is scheduled to cpu B, we need flush cache.

Thanks,
Jinsong
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