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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.12.13 at 15:30, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
> 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.
> 
> 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.

But you didn't clarify whether/how this case was taken care of
_before_ your XSA-60 patches.

Jan


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