From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3w1c8z2TmRzDq7Z for ; Mon, 10 Apr 2017 14:07:47 +1000 (AEST) Message-ID: <1491797258.4166.205.camel@kernel.crashing.org> Subject: Re: [PATCH 1/5] powerpc/pseries: do not use msgsndp doorbells on POWER9 guests From: Benjamin Herrenschmidt To: Nicholas Piggin Cc: linuxppc-dev@lists.ozlabs.org, Paul Mackerras Date: Mon, 10 Apr 2017 14:07:38 +1000 In-Reply-To: <20170410132245.16802599@roar.ozlabs.ibm.com> References: <20170407125602.31146-1-npiggin@gmail.com> <20170407125602.31146-2-npiggin@gmail.com> <1491725015.4166.188.camel@kernel.crashing.org> <20170410132245.16802599@roar.ozlabs.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2017-04-10 at 13:22 +1000, Nicholas Piggin wrote: > On Sun, 09 Apr 2017 18:03:35 +1000 > > Benjamin Herrenschmidt wrote: > > > On Fri, 2017-04-07 at 22:55 +1000, Nicholas Piggin wrote: > > > POWER9 hypervisors will not necessarily run guest threads together on > > > the same core at the same time, so msgsndp should not be used.   > > > > Maybe we shouldn't advertise doorbells at all ? > > Possibly not. I don't know if there is a good way to switch it off > in the guest from the host with device tree currently. Might be better > to clear it early in the guest rather than test it here though? Sure for now. Long term a separate DT entry would be good. Might be worth re-enabling one day if we have HW virtualization of geust doorbells. Cheers, Ben