linux-kernel - Re: perf with precise attribute kills all KVM based VMs

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Date:	Mon, 09 Jul 2012 16:24:04 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Gleb Natapov <gleb@...hat.com>
Cc:	David Ahern <dsahern@...il.com>, Avi Kivity <avi@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: perf with precise attribute kills all KVM based VMs

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?

Quality stuff..

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?
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