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 12:24:38 +0300 [thread overview]
Message-ID: <20100801092438.GE24773@redhat.com> (raw)
In-Reply-To: <4C553B00.8030100@redhat.com>
On Sun, Aug 01, 2010 at 12:14:40PM +0300, Avi Kivity wrote:
> On 08/01/2010 12:01 PM, Gleb Natapov wrote:
> >>>
> >>>It uses rip _during_ pio. And pio emulation changes rip
> >>>only at the end of emulation.
> >>But non-emulated pio does a skip_emulated_instruction() immediately
> >>(or so the code in kvm-tpr-opt.c assumes:
> >>
> >Indeed, this is bug in non-emulated pio.
>
> But userspace depends on this bug.
We can fix that, or make it smarter. Look for io instruction at
rip/rip-2 and use rip accordingly for instance.
>
> >But the patch does not change
> >rip behaviour for emulated pio. vcpu->arch.emulate_ctxt.eip is updated
> >only at the end of emulation.
>
> That will lead to failures if the emulator is used for the
> kvm-tpr-opt pio (which may happen with big real mode).
>
IIRC it was always this way in emulator. I'd rather fix userspace than
break emulator.
--
Gleb.
next prev parent reply other threads:[~2010-08-01 9:24 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 [this message]
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
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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