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From: Chris Lalancette <clalance@redhat.com>
To: Avi Kivity <avi@qumranet.com>
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>
Subject: Re: [PATCH]: Fix MSR_K7_EVNTSEL{0,3} for SVM
Date: Thu, 24 Apr 2008 18:13:15 -0400	[thread overview]
Message-ID: <481105FB.1080705@redhat.com> (raw)
In-Reply-To: <4810A538.1070104@qumranet.com>

Avi Kivity wrote:
> Now it uses %rsi instead of %esi, and any junk in the upper bits will 
> cause the ja to be taken.
> 
> We need to get a reduced testcase to the gcc folks, this is a serious 
> bug.  Any changes in the code to work around this would be fragile.
> 

Avi,
    I've now filed a bug in the upstream gcc database:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36040

And I came up with a reduced test case, available here:

http://people.redhat.com/clalance/rsi-test-case.tar.bz2

If I compile the code in the above and look at the disassembly, it shows the
problem; however, I can't reproduce the bug by actually running the code.  I
suspect the %rsi register is always 0 when we start in this userland code, so I
never run into the bogus ja, but I just thought I'd mention it.

Chris Lalancette

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  parent reply	other threads:[~2008-04-24 22:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-04-23 18:23 [PATCH]: Fix MSR_K7_EVNTSEL{0,3} for SVM Chris Lalancette
2008-04-24  7:35 ` Avi Kivity
     [not found]   ` <4810926E.3070900@redhat.com>
2008-04-24 15:20     ` Avi Kivity
2008-04-24 15:44       ` Chris Lalancette
2008-04-24 22:13       ` Chris Lalancette [this message]
2008-04-25  7:30         ` Avi Kivity
2008-04-25 13:06           ` Chris Lalancette
2008-04-25 18:43           ` Chris Lalancette
2008-04-28 12:46             ` Joerg Roedel
2008-04-28 14:17               ` Chris Lalancette
2008-04-28 15:57                 ` Joerg Roedel
2008-04-28 16:38                   ` Chris Lalancette
2008-04-28 16:41                 ` Andi Kleen

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