From: Gleb Natapov <gleb@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: mtosatti@redhat.com, kvm@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted.
Date: Sun, 1 Aug 2010 15:23:16 +0300 [thread overview]
Message-ID: <20100801122316.GG24773@redhat.com> (raw)
In-Reply-To: <4C5565C6.1090004@redhat.com>
On Sun, Aug 01, 2010 at 03:17:10PM +0300, Avi Kivity wrote:
> On 08/01/2010 01:53 PM, Gleb Natapov wrote:
> >
> >>That requires everyone to update, or suffer major breakage.
> >>
> >They will suffer major breakage when they update to a kvm that calls to
> >kvm-tpr-opt.c from emulator anyway.
>
> Why?
>
Because tpr code will be called with wrong rip. Emulator always updated rip at the end
of an instruction emulation in writeback stage.
> >>>IIRC it was always this way in emulator. I'd rather fix userspace than
> >>>break emulator.
> >>It wasn't a problem because the emulator wasn't (and still isn't)
> >>used for this. But it has the potential to break badly once we make
> >>emulate_invalid_guest_state=1 the default.
> >>
> >So what can we do about it?
> >
>
> Keep the existing behaviour.
>
Existing behaviour will cause breakage.
--
Gleb.
next prev parent reply other threads:[~2010-08-01 12:23 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-29 12:11 [PATCH 0/2] Speedup ins instruction emulation a little Gleb Natapov
2010-07-29 12:11 ` [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted Gleb Natapov
2010-07-31 17:25 ` Avi Kivity
2010-08-01 8:28 ` Gleb Natapov
2010-08-01 8:54 ` Avi Kivity
2010-08-01 9:01 ` Gleb Natapov
2010-08-01 9:14 ` Avi Kivity
2010-08-01 9:24 ` Gleb Natapov
2010-08-01 10:00 ` Avi Kivity
2010-08-01 10:53 ` Gleb Natapov
2010-08-01 12:17 ` Avi Kivity
2010-08-01 12:23 ` Gleb Natapov [this message]
2010-08-01 12:35 ` Avi Kivity
2010-08-01 13:27 ` Gleb Natapov
2010-08-02 5:04 ` Avi Kivity
2010-08-02 7:58 ` Gleb Natapov
2010-08-02 8:03 ` Avi Kivity
2010-08-02 8:17 ` Gleb Natapov
2010-08-02 8:24 ` Avi Kivity
2010-08-02 8:34 ` Gleb Natapov
2010-08-02 8:54 ` Avi Kivity
2010-08-02 9:05 ` Gleb Natapov
2010-08-02 9:08 ` Avi Kivity
2010-07-29 12:11 ` [PATCH 2/2] KVM: x86 emulator: check io permissions only once for string pio Gleb Natapov
2010-07-31 1:59 ` Marcelo Tosatti
2010-07-29 12:19 ` [PATCH 0/2] Speedup ins instruction emulation a little Avi Kivity
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