From: Gleb Natapov <gleb@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: David Ahern <dsahern@gmail.com>, Avi Kivity <avi@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: perf with precise attribute kills all KVM based VMs
Date: Mon, 9 Jul 2012 17:36:58 +0300 [thread overview]
Message-ID: <20120709143658.GD7298@redhat.com> (raw)
In-Reply-To: <1341843844.3462.75.camel@twins>
On Mon, Jul 09, 2012 at 04:24:04PM +0200, Peter Zijlstra wrote:
> On Mon, 2012-07-09 at 17:19 +0300, Gleb Natapov wrote:
> > Yes, this is knows problem that I can't find time to fix. The crash is
> > cause by CPU using host PEBS virtual address while guest is running
> > which causes guest memory corruption. We should disable evens that use
> > PEBS at the guest entry.
>
> Whoops.. so the hardware is reading the DS address as programmed by the
> host (host linear address) and using it as a guest linear address?
>
Yes.
> Quality stuff..
DS area and vitalization are definitely not friends.
>
> Disabling PEBS events for guests isn't pretty though.. but I guess the
> only alternative is mapping the DS into the guest and reprogramming
> MSR_IA32_DS_AREA which is all a little involved I suppose?
This needs guest cooperation which is possible with PV guest of course,
but there is a security issue here. Intel SDM requires that DS have to
be mapped by page table at all time and marked dirty/accessed otherwise
unspecified bad things can happen. Nothing prevents guest from unmapping
DS and cause host troubles.
--
Gleb.
next prev parent reply other threads:[~2012-07-09 14:37 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-09 14:12 perf with precise attribute kills all KVM based VMs David Ahern
2012-07-09 14:19 ` Gleb Natapov
2012-07-09 14:24 ` Peter Zijlstra
2012-07-09 14:36 ` Gleb Natapov [this message]
2012-07-09 14:39 ` Avi Kivity
2012-07-09 14:47 ` David Ahern
2012-07-09 14:49 ` Peter Zijlstra
2012-07-09 14:51 ` Avi Kivity
2012-07-09 14:54 ` Gleb Natapov
2012-07-09 14:57 ` Gleb Natapov
2012-07-09 14:59 ` Peter Zijlstra
2012-07-10 23:38 ` David Ahern
2012-07-11 7:10 ` Gleb Natapov
2012-07-11 9:49 ` Peter Zijlstra
2012-07-11 9:53 ` Gleb Natapov
2012-07-11 13:34 ` David Ahern
2012-07-12 4:11 ` David Ahern
2012-07-12 4:29 ` Gleb Natapov
2012-07-12 15:20 ` David Ahern
2012-07-12 16:06 ` Gleb Natapov
2012-07-12 16:13 ` Gleb Natapov
2012-07-12 16:58 ` Peter Zijlstra
2012-07-16 1:51 ` David Ahern
2012-07-15 8:07 ` Avi Kivity
2012-07-15 13:00 ` David Ahern
2012-07-15 13:03 ` Avi Kivity
2012-07-16 1:52 ` David Ahern
2012-07-16 2:19 ` David Ahern
2012-07-20 23:34 ` David Ahern
2012-07-22 9:52 ` Avi Kivity
2012-07-09 14:52 ` David Ahern
2012-07-09 14:58 ` David Ahern
2012-07-09 15:18 ` David Ahern
2012-07-09 14:47 ` Peter Zijlstra
2012-07-20 23:35 ` David Ahern
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