Subject: Re: kvm causing memory corruption?  now 2.6.26-rc4
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Avi Kivity <avi@qumranet.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       kvm-devel <kvm@vger.kernel.org>,
       "Anthony N. Liguori [imap]" <aliguori@us.ibm.com>
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Date: Fri, 06 Jun 2008 00:41:45 -0700
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On Wed, 2008-06-04 at 16:42 +0300, Avi Kivity wrote:
> Dave Hansen wrote:
...
> > After collecting all those, I turned on CONFIG_DEBUG_HIGHMEM and the
> > oopses miraculously stopped.  But, the guest hung (for at least 5
> > minutes or so) during windows bootup, pegging my host CPU.  Most of the
> > CPU was going to klogd, so I checked dmesg.
> >
> Can you check with mem=900 (and CONFIG_HIGHMEM_DEBUG=n)?  That will 
> confirm that the problems are highmem related, but not physical address 
> truncation related.

Do you mean 800M? ;) Highmem begins at 896MB if I remember correctly.

Anyway, it still oopses on current git with mem=800M

> > I was seeing messages like this
> >
> > [  428.918108] kvm_handle_exit: unexpected, valid vectoring info and exit reason is 0x9
> >
> > And quite a few of them, like 100,000/sec.  That's why klogd was pegging
> > the CPU.  Any idea on a next debugging step?
> >
> That's a task switch.  Newer kvms handle them.

Newer userspace?  I'm running current kvm-git userspace as of a day or
two ago.

-- Dave

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