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Subject: Re: [PATCH 0/2] powerpc/xive: fix CPU hot unplug
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: =?ISO-8859-1?Q?C=E9dric?= Le Goater <clg@kaod.org>,
 linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>, David Gibson
 <david@gibson.dropbear.id.au>
Date: Mon, 02 Oct 2017 18:52:37 +0200
In-Reply-To: <378a1945-6263-dca7-3912-b4a2c61794b8@kaod.org>
References: <20170923082656.27219-1-clg@kaod.org>
 <378a1945-6263-dca7-3912-b4a2c61794b8@kaod.org>
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On Mon, 2017-10-02 at 18:27 +0200, Cédric Le Goater wrote:
> On 09/23/2017 10:26 AM, Cédric Le Goater wrote:
> > Hi,
> > 
> > Here are a couple of small fixes to support CPU hot unplug. There are
> > still some issues to be investigated as, in some occasions, after a
> > couple of plug and unplug, the cpu which was removed receives a 'lost'
> > interrupt. This showed to be the decrementer under QEMU.
> 
> So this seems to be a QEMU issue only which can be solved by 
> removing the DEE bit from the LPCR on P9 processor when the CPU 
> is stopped in rtas. PECE3 bit on P8 processors. 

It should be the same bit no ?

> I think these patches are valuable fixes for 4.14. The first 
> is trivial and the second touches the common xive part but it
> is only called on the pseries platform.  
> 
> Could you please take a look ? 
> 
> Thanks,
> 
> C. 
> 
> > Nevertheless, these patches are required and provide a significant
> > improvement to support CPU removal.
> > 
> > Tested under a phyp and a XIVE QEMU model for pseries.
> > 
> > Thanks,
> > 
> > C.
> > 
> > Cédric Le Goater (2):
> >   powerpc/xive: fix IPI reset
> >   powerpc/xive: fix cpu removal
> > 
> >  arch/powerpc/sysdev/xive/common.c | 8 ++++++++
> >  arch/powerpc/sysdev/xive/spapr.c  | 4 ++++
> >  2 files changed, 12 insertions(+)
> >