linux-kernel - Re: [PATCH] pseries/le: Fix another endiannes issue in RTAS call from xmon

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Message-ID: <1421377361.18166.2.camel@ellerman.id.au>
Date:	Fri, 16 Jan 2015 14:02:41 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Tyrel Datwyler <tyreld@...ux.vnet.ibm.com>
Cc:	linuxppc-dev@...ts.ozlabs.org,
	Laurent Dufour <ldufour@...ux.vnet.ibm.com>, paulus@...ba.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pseries/le: Fix another endiannes issue in RTAS call
 from xmon

On Thu, 2015-01-15 at 15:41 -0800, Tyrel Datwyler wrote:
> On 01/15/2015 02:19 PM, Michael Ellerman wrote:
> > On Thu, 2015-01-15 at 11:44 -0800, Tyrel Datwyler wrote:
> >> On 01/15/2015 09:23 AM, Laurent Dufour wrote:
> >>> The commit 3b8a3c010969 ("powerpc/pseries: Fix endiannes issue in RTAS
> >>> call from xmon") was fixing an endianness issue in the call made from
> >>> xmon to RTAS.
> >>>
> >>> However, as Michael Ellerman noticed, this fix was not complete, the
> >>> token value was not byte swapped. This lead to call an unexpected and
> >>> most of the time unexisting RTAS function, which is silently ignored
> >>> by RTAS.
> >>
> >> Nit. Not so much that is silently ignored by RTAS as much as
> >> disable_surveillance silently doesn't check the return status of the
> >> RTAS call. Maybe a check is warranted and reporting of non-success.
> > 
> > Yeah you're right, I added a printf of the result and got -3, which is also
> > wrong as far as I can tell, but I didn't have the energy to chase it any
> > further.
> 
> If this was on a powerkvm guest set-indicator should be present for
> hotplug (DLPAR) support. However, the surveillance indicator would not
> be implemented. I know sometimes I forget if I'm on a powervm or
> powerkvm guest. Just a thought.

Right that does explain it. I went looking for the KVM kernel/qemu code that
implements set-indicator but couldn't find it. Presumably it's in some branch
other than the one I was looking at, or I was grepping for the wrong thing.

So I guess a printf there is probably not helpful, because it will fire always
on PowerKVM (at least at the moment).

cheers


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