From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: kvm ptrace 32bit DoS bug - bisected
Date: Tue, 8 Sep 2009 13:33:12 -0300
Message-ID: <20090908163312.GA18155@amt.cnet>
References: <4AA26A86.8060908@nagafix.co.uk> <20090905204336.GA6991@amt.cnet> <4AA366AA.7010806@nagafix.co.uk> <4AA369A8.3040008@nagafix.co.uk>
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Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Roland McGrath <roland@redhat.com>,
	Jan Kiszka <jan.kiszka@web.de>
To: Antoine Martin <antoine@nagafix.co.uk>
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On Sun, Sep 06, 2009 at 02:50:00PM +0700, Antoine Martin wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
> 
> [snip]
> >> Is this an AMD host? 
> > Nope, Intel Core2, more host info :
> I have put all the relevant binaries and their config files here:
> http://uml.devloop.org.uk/kvmbug/
> Host kernel, qemu binary, kvm guest kernel and the UML binary I have
> used for bisecting.

Antoine,

Works for me with master branch. Its likely this commit fixed it:

commit 76d4622776d007de3f90f311591babc5f6ba6f39
Author: Avi Kivity <avi@redhat.com>
Date:   Tue Sep 1 12:03:25 2009 +0300

    KVM: VMX: Check cpl before emulating debug register access
    
    Debug registers may only be accessed from cpl 0.  Unfortunately, vmx will
    code to emulate the instruction even though it was issued from guest
    userspace, possibly leading to an unexpected trap later.

It will be included in 2.6.30 / 2.6.27 stable (.29 is not maintained
anymore).