From: Avi Kivity <avi@qumranet.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>,
Zdenek Kabelac <zdenek.kabelac@gmail.com>
Subject: Re: [PATCH] prepopulate guest pages after write-protecting
Date: Sat, 05 Apr 2008 00:06:15 +0300 [thread overview]
Message-ID: <47F69847.7090609@qumranet.com> (raw)
In-Reply-To: <20080404175644.GA444@dmt>
Marcelo Tosatti wrote:
> Zdenek reported a bug where a looping "dmsetup status" eventually hangs
> on SMP guests.
>
> The problem is that kvm_mmu_get_page() prepopulates the shadow MMU
> before write protecting the guest page tables. By doing so, it leaves a
> window open where the guest can mark a pte as present while the host has
> shadow cached such pte as "notrap". Accesses to such address will fault
> in the guest without the host having a chance to fix the situation.
>
Applied, thanks. Impressive catch.
--
Any sufficiently difficult bug is indistinguishable from a feature.
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prev parent reply other threads:[~2008-04-04 21:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-04 17:56 [PATCH] prepopulate guest pages after write-protecting Marcelo Tosatti
2008-04-04 19:08 ` Zdenek Kabelac
2008-04-04 21:06 ` Avi Kivity [this message]
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