From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: lguest@ozlabs.org, Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 3/5] lguest: avoid accidental recycling of pgdir pages
Date: Fri, 27 Mar 2009 09:28:12 -0700 [thread overview]
Message-ID: <49CCFE9C.6060702@goop.org> (raw)
In-Reply-To: <200903271154.22450.rusty@rustcorp.com.au>
Rusty Russell wrote:
>> You can't just do this in tlb flush?
>>
>
> I don't think so. The problem is that lguest tracks 4 toplevels, using random
> replacement. This cache is indexed by cr3 value.
>
> Lguest assumes it's told about all pte removals or changes, but simple
> additions get faulted in. If a pgdir page gets reused we'll potentially have
> stale values from its previous life as a pgdir, no?
>
Yes, but when you get a tlb flush hypercall, couldn't you also look up
the corresponding shadow pte and zap it so that it will get repopulated
next time around? And a full tlb flush would just zap the entire
shadow. After all, the shadow pagetable is just a glorified
software-managed tlb...
J
next prev parent reply other threads:[~2009-03-27 16:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-26 23:52 [PATCH 3/5] lguest: avoid accidental recycling of pgdir pages Rusty Russell
2009-03-27 0:17 ` Jeremy Fitzhardinge
2009-03-27 1:24 ` Rusty Russell
2009-03-27 16:28 ` Jeremy Fitzhardinge [this message]
2009-03-27 16:33 ` Jeremy Fitzhardinge
2009-03-28 6:37 ` Rusty Russell
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