Re: [Xen-devel] [PATCH] x86/HVM: fix interaction between internal and extern emulation

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 28 November 2017 12:04
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>; Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; xen-devel <xen-
> devel@xxxxxxxxxxxxxxxxxxxx>
> Subject: RE: [PATCH] x86/HVM: fix interaction between internal and extern
> emulation
> 
> >>> On 28.11.17 at 12:58, <Paul.Durrant@xxxxxxxxxx> wrote:
> >>  -----Original Message-----
> >> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf
> >> Of Paul Durrant
> >> Sent: 28 November 2017 11:31
> >> To: 'Jan Beulich' <JBeulich@xxxxxxxx>
> >> Cc: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Julien Grall
> >> <julien.grall@xxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> >> Subject: Re: [Xen-devel] [PATCH] x86/HVM: fix interaction between
> internal
> >> and extern emulation
> >>
> >> > -----Original Message-----
> >> > From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> > Sent: 28 November 2017 11:26
> >> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> >> > Cc: Julien Grall <julien.grall@xxxxxxx>; Andrew Cooper
> >> > <Andrew.Cooper3@xxxxxxxxxx>; xen-devel <xen-
> >> > devel@xxxxxxxxxxxxxxxxxxxx>
> >> > Subject: RE: [PATCH] x86/HVM: fix interaction between internal and
> extern
> >> > emulation
> >> >
> >> > >>> On 28.11.17 at 12:06, <Paul.Durrant@xxxxxxxxxx> wrote:
> >> > > Yes, it appears that mmio_retry is only set when the underlying
> >> emulation
> >> > > returned X86EMUL_OKAY but not all reps were completed. If the
> >> > underlying
> >> > > emulation did not return X86EMUL_RETRY then I can't figure out why
> >> > > vio->io_completion should need to be set to anything other than
> >> > > HVMIO_no_completion since any other return value indicates there
> >> should
> >> > be
> >> > > nothing pending.
> >> >
> >> > So am I getting it right that you're suggesting to remove the
> >> > mmio_retry part of the condition in hvm_emulate_one_insn()?
> >> > That looks like it might work (I was previously only considering
> >> > to get rid of mmio_retry altogether, and that didn't look like a
> >> > viable route).
> >>
> >> Yes, that's what I'm suggesting. I really can't see why it is needed. It
> > could
> >> have been a mistake in my original patches or a semantic change in a
> >> subsequent patch, but it certainly looks wrong in current context.
> >> Andrew has just sent me his xtf repro so I'll give the change a go with
> > that.
> >
> > Yes, this patch fixed the problem for me. I'll do some more tests to check
> > for collateral damage now... If it's all good, do you want me to submit it 
> > or
> > do you want to send it as a v2 of your patch?
> 
> It's yours, so please submit it (perhaps nevertheless as v2). Feel
> free to add my R-b right away if no other change turns out
> necessary.

Ok. Will do. Thanks,

  Paul

> 
> Jan


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