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Re: [Xen-devel] [Patch] Enable SMEP CPU feature support for XEN itself

To: "Li, Xin" <xin.li@xxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>, "Yang, Wei Y" <wei.y.yang@xxxxxxxxx>
Subject: Re: [Xen-devel] [Patch] Enable SMEP CPU feature support for XEN itself
From: Keir Fraser <keir.xen@xxxxxxxxx>
Date: Fri, 03 Jun 2011 13:34:04 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] [Patch] Enable SMEP CPU feature support for XEN itself
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On 03/06/2011 12:54, "Li, Xin" <xin.li@xxxxxxxxx> wrote:

>>> The whole point of setup_clear_cpu_cap() is that it only needs to run on the
>>> BP and the change gets picked up by every AP automatically as it boots.
>> Yeah, and we can't do leaf 7.0 detect in generic_identify. Or will again set
>> SMEP in
>> capabilities, but it should be ok.
> I tried to not do leaf 7.0 detect on AP booting code, but system behaves
> abnormally
> (not hang, but "su -" never returns, after just revert the change, it runs
> well).
> While at this point I want to focus on SMEP logic, we can make the
> improvements,
> to move such initialization to BP code only, later.  Also it makes no much
> sense to only
> move disable_smep that way, we should move all such variables.

Just get another rev of the patches out and we'll iterate if necessary.

 -- Keir

> Thanks!
> -Xin

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