From: Avi Kivity <avi@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: 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, mtosatti@redhat.com
Subject: Re: [PATCH v6 08/12] Handle async PF in a guest.
Date: Sun, 10 Oct 2010 14:40:50 +0200 [thread overview]
Message-ID: <4CB1B452.2060707@redhat.com> (raw)
In-Reply-To: <20101010075625.GM2397@redhat.com>
On 10/10/2010 09:56 AM, Gleb Natapov wrote:
> On Sat, Oct 09, 2010 at 08:48:15PM +0200, Avi Kivity wrote:
> > On 10/07/2010 08:03 PM, Gleb Natapov wrote:
> > >> >>
> > >> >Host side keeps track of outstanding apfs and will not send apf for the
> > >> >same phys address twice. It will halt vcpu instead.
> > >>
> > >> What about different pages, running the scheduler code?
> > >>
> > >We can get couple of nested apfs, just like we can get nested
> > >interrupts. Since scheduler disables preemption second apf will halt.
> >
> > How much is a couple?
> >
> > Consider:
> >
> > SIGSTOP
> > Entire process swapped out
> > SIGCONT
> >
> > We can get APF's on the current code, the scheduler code, the stack,
> > any debugging code in between (e.g. ftrace), and the page tables for
> > all of these.
> >
> Lets count them all. Suppose guest is in a userspace process code and
> guest memory is completely swapped out. Guest starts to run and faults
> in userspace. Apf is queued but can't be delivered due to faults in
> idt and exception stack. All of them will be taken synchronously due
> to event pending check. After apf is delivered any fault in apf code
> will be takes synchronously since interrupt are disabled. Just before
> calling schedule() interrupts are enabled, so next pf that will happen
> during call to schedule() will be taken asynchronously. Which will cause
> another call to schedule() at which point vcpu will be halted since two
> apfs happened at the same address. So I counted two of them.
>
Ok. Feels weird, but I guess this is fine.
--
error compiling committee.c: too many arguments to function
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next prev parent reply other threads:[~2010-10-10 12:41 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
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 [this message]
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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