From: Gleb Natapov <gleb@minantech.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, Gleb Natapov <gleb@redhat.com>,
kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, mingo@elte.hu,
a.p.zijlstra@chello.nl, tglx@linutronix.de, hpa@zytor.com,
riel@redhat.com, cl@linux-foundation.org
Subject: Re: [PATCH v6 04/12] Add memory slot versioning and use it to provide fast guest write interface
Date: Thu, 7 Oct 2010 18:03:41 +0200 [thread overview]
Message-ID: <20101007160340.GD4120@minantech.com> (raw)
In-Reply-To: <20101007154248.GA30949@amt.cnet>
On Thu, Oct 07, 2010 at 12:42:48PM -0300, Marcelo Tosatti wrote:
> On Thu, Oct 07, 2010 at 12:00:13PM +0200, Avi Kivity wrote:
> > On 10/06/2010 10:08 PM, Gleb Natapov wrote:
> > >> Malicious userspace can cause entry to be cached, ioctl
> > >> SET_USER_MEMORY_REGION 2^32 times, generation number will match,
> > >> mark_page_dirty_in_slot will be called with pointer to freed memory.
> > >>
> > >Hmm. To zap all cached entires on overflow we need to track them. If we
> > >will track then we can zap them on each slot update and drop "generation"
> > >entirely.
> >
> > To track them you need locking.
> >
> > Isn't SET_USER_MEMORY_REGION so slow that calling it 2^32 times
> > isn't really feasible?
>
> Assuming it takes 1ms, it would take 49 days.
>
We may fail ioctl when max value is reached. The question is how much slot
changes can we expect from real guest during its lifetime.
> > In any case, can use u64 generation count.
>
> Agree.
Yes, 64 bit ought to be enough for anybody.
--
Gleb.
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next prev parent reply other threads:[~2010-10-07 16:03 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-04 15:56 [PATCH v6 00/12] KVM: Add host swap event notifications for PV guest Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 01/12] Add get_user_pages() variant that fails if major fault is required Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 02/12] Halt vcpu if page it tries to access is swapped out Gleb Natapov
2010-10-05 1:20 ` Rik van Riel
2010-10-05 14:59 ` Marcelo Tosatti
2010-10-06 10:50 ` Avi Kivity
2010-10-06 10:52 ` Gleb Natapov
2010-10-07 9:54 ` Avi Kivity
2010-10-07 17:48 ` Gleb Natapov
2010-10-06 11:15 ` Gleb Natapov
2010-10-07 9:50 ` Avi Kivity
2010-10-07 9:52 ` Avi Kivity
2010-10-07 13:24 ` Rik van Riel
2010-10-07 13:29 ` Avi Kivity
2010-10-07 17:47 ` Gleb Natapov
2010-10-09 18:30 ` Avi Kivity
2010-10-09 18:32 ` Avi Kivity
2010-10-10 7:30 ` Gleb Natapov
2010-10-10 7:29 ` Gleb Natapov
2010-10-10 15:55 ` Avi Kivity
2010-10-10 15:56 ` Avi Kivity
2010-10-10 16:17 ` Gleb Natapov
2010-10-10 16:16 ` Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 03/12] Retry fault before vmentry Gleb Natapov
2010-10-05 15:54 ` Marcelo Tosatti
2010-10-06 11:07 ` Gleb Natapov
2010-10-06 14:20 ` Marcelo Tosatti
2010-10-07 18:44 ` Gleb Natapov
2010-10-08 16:07 ` Marcelo Tosatti
2010-10-07 12:29 ` Avi Kivity
2010-10-07 17:21 ` Gleb Natapov
2010-10-09 18:42 ` Avi Kivity
2010-10-10 7:35 ` Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 04/12] Add memory slot versioning and use it to provide fast guest write interface Gleb Natapov
2010-10-05 1:29 ` Rik van Riel
2010-10-05 16:57 ` Marcelo Tosatti
2010-10-06 11:14 ` Gleb Natapov
2010-10-06 14:38 ` Marcelo Tosatti
2010-10-06 20:08 ` Gleb Natapov
2010-10-07 10:00 ` Avi Kivity
2010-10-07 15:42 ` Marcelo Tosatti
2010-10-07 16:03 ` Gleb Natapov [this message]
2010-10-07 16:20 ` Avi Kivity
2010-10-07 17:23 ` Gleb Natapov
2010-10-10 12:48 ` Avi Kivity
2010-10-07 12:31 ` Avi Kivity
2010-10-04 15:56 ` [PATCH v6 05/12] Move kvm_smp_prepare_boot_cpu() from kvmclock.c to kvm.c Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 06/12] Add PV MSR to enable asynchronous page faults delivery Gleb Natapov
2010-10-07 12:42 ` Avi Kivity
2010-10-07 17:53 ` Gleb Natapov
2010-10-10 12:47 ` Avi Kivity
2010-10-10 13:27 ` Gleb Natapov
2010-10-07 12:58 ` Avi Kivity
2010-10-07 17:59 ` Gleb Natapov
2010-10-09 18:43 ` Avi Kivity
2010-10-04 15:56 ` [PATCH v6 07/12] Add async PF initialization to PV guest Gleb Natapov
2010-10-05 2:34 ` Rik van Riel
2010-10-05 18:25 ` Marcelo Tosatti
2010-10-06 10:55 ` Gleb Natapov
2010-10-06 14:45 ` Marcelo Tosatti
2010-10-06 20:05 ` Gleb Natapov
2010-10-07 12:50 ` Avi Kivity
2010-10-08 7:54 ` Gleb Natapov
2010-10-09 18:44 ` Avi Kivity
2010-10-04 15:56 ` [PATCH v6 08/12] Handle async PF in a guest Gleb Natapov
2010-10-07 13:10 ` Avi Kivity
2010-10-07 17:14 ` Gleb Natapov
2010-10-07 17:18 ` Avi Kivity
2010-10-07 17:48 ` Rik van Riel
2010-10-07 18:03 ` Gleb Natapov
2010-10-09 18:48 ` Avi Kivity
2010-10-10 7:56 ` Gleb Natapov
2010-10-10 12:40 ` Avi Kivity
2010-10-10 12:32 ` Gleb Natapov
2010-10-10 12:38 ` Avi Kivity
2010-10-10 13:22 ` Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 09/12] Inject asynchronous page fault into a PV guest if page is swapped out Gleb Natapov
2010-10-05 2:36 ` Rik van Riel
2010-10-05 19:00 ` Marcelo Tosatti
2010-10-06 10:42 ` Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 10/12] Handle async PF in non preemptable context Gleb Natapov
2010-10-05 19:51 ` Marcelo Tosatti
2010-10-06 10:41 ` Gleb Natapov
2010-10-10 14:25 ` Gleb Natapov
2010-10-04 15:56 ` [PATCH v6 11/12] Let host know whether the guest can handle async PF in non-userspace context Gleb Natapov
2010-10-07 13:36 ` Avi Kivity
2010-10-04 15:56 ` [PATCH v6 12/12] Send async PF when guest is not in userspace too Gleb Natapov
2010-10-05 2:37 ` Rik van Riel
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