From: Keir Fraser <keir@xen.org>
To: Mats Petersson <mats.petersson@citrix.com>, xen-devel@lists.xen.org
Subject: Re: [PATCH V2] xen: vmx: Use an INT 2 call to process real NMI's instead of self_nmi() in VMEXIT handler
Date: Fri, 16 Nov 2012 10:18:22 +0000 [thread overview]
Message-ID: <CCCBC36E.5256B%keir@xen.org> (raw)
In-Reply-To: <50A60E8C.9070608@citrix.com>
On 16/11/2012 09:59, "Mats Petersson" <mats.petersson@citrix.com> wrote:
>>> Yes, I hadn't thought of that case.
>> But what would make a fault happen on that IRET? Oh, yes,
>> there is one case - the guest having its previous instruction end
>> exactly at the canonical/non-canonical boundary. But for the
>> sake of correctness, that's a #GP then. I would suppose this
>> would better be filtered (manually injecting a #GP into the guest)
>> than allowed to actually cause a #GP.
> Or, if for some reason the address we return to is "not present". Now,
> in the current Xen, Xen itself doesn't get paged out, but in a PV guest,
> I'm pretty certain the guest could decide to page out some code-page,
> which just happens to be the one we were about to return to?
That fault would occur in the context being returned to, with rIP == the
IRET return target.
-- Keir
next prev parent reply other threads:[~2012-11-16 10:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-13 20:08 [PATCH V2] xen: vmx: Use an INT 2 call to process real NMI's instead of self_nmi() in VMEXIT handler Malcolm Crossley
2012-11-14 10:06 ` Jan Beulich
2012-11-15 16:41 ` Tim Deegan
2012-11-15 16:52 ` Andrew Cooper
2012-11-15 17:25 ` Tim Deegan
2012-11-16 8:17 ` Jan Beulich
2012-11-16 9:59 ` Mats Petersson
2012-11-16 10:18 ` Keir Fraser [this message]
2012-11-15 17:03 ` Mats Petersson
2012-11-15 17:15 ` Tim Deegan
2012-11-15 17:33 ` Mats Petersson
2012-11-15 17:44 ` Tim Deegan
2012-11-15 18:23 ` Mats Petersson
2012-11-16 8:07 ` Jan Beulich
2012-11-16 10:56 ` Tim Deegan
2012-11-16 11:23 ` Jan Beulich
2012-11-16 11:52 ` Andrew Cooper
2012-11-16 13:53 ` Tim Deegan
2012-11-16 14:11 ` Andrew Cooper
2012-11-22 8:58 ` Jan Beulich
2012-11-22 10:52 ` Andrew Cooper
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