From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Tim Deegan <Tim.Deegan@citrix.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: Re: issues with movnti emulation
Date: Thu, 20 Nov 2008 17:43:08 +0000 [thread overview]
Message-ID: <C54B522C.1F72A%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <20081120171641.GJ25331@york.uk.xensource.com>
On 20/11/08 17:16, "Tim Deegan" <Tim.Deegan@citrix.com> wrote:
> At 17:13 +0000 on 20 Nov (1227201181), Keir Fraser wrote:
>> I think the issue is that I did a bad backport to 3.3. The 'case 0xc3'
>> should be under twobyte_special_insn rather than twobyte_insn, right? The
>> two separate paths got merged into one in xen-unstable.
>>
>> Of course this data corruption ought only to happen in cases where we'd
>> previously have failed an mmio emulation (and hence probably killed the
>> guest kernel?).
>
> A more likely culprit is that some OSes use movnti to zero pages that
> used to be pagetables; when we couldn't emulate it we just (correctly)
> unshadowed those pages.
Yes, you're probably right. I wonder if we are relying on emulation failures
to inform unshadowing at all often? We might have to revisit constraining
x86_emulate() when called by shadow code, do you think?
-- Keir
next prev parent reply other threads:[~2008-11-20 17:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-20 16:38 issues with movnti emulation Jan Beulich
2008-11-20 17:13 ` Keir Fraser
2008-11-20 17:16 ` Tim Deegan
2008-11-20 17:43 ` Keir Fraser [this message]
2008-11-21 16:01 ` Tim Deegan
2008-11-24 16:18 ` Gianluca Guida
2008-11-24 15:34 ` Jan Beulich
2008-11-20 18:42 ` Kevin Wolf
2008-11-21 11:04 ` Jan Beulich
2008-11-21 11:19 ` Keir Fraser
2008-11-25 14:01 ` Gianluca Guida
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