From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from va3outboundpool.messaging.microsoft.com (va3ehsobe002.messaging.microsoft.com [216.32.180.12]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id E2F242C00B6 for ; Tue, 23 Jul 2013 08:19:19 +1000 (EST) Date: Mon, 22 Jul 2013 17:19:08 -0500 From: Scott Wood To: Alexander Graf Subject: Re: PPC: Don't sync timebase when inside VM Message-ID: <20130722221908.GA26079@home.buserror.net> References: <1330697553-27156-1-git-send-email-agraf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <1330697553-27156-1-git-send-email-agraf@suse.de> Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Mar 02, 2012 at 03:12:33PM +0100, Alexander Graf wrote: > When running inside a virtual machine, we can not modify timebase, so > let's just not call the functions for it then. > > This resolves hangs when booting e500 SMP guests on overcommitted hosts. > > Reported-by: Stuart Yoder > Signed-off-by: Alexander Graf > > --- > arch/powerpc/platforms/85xx/smp.c | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c > index ff42490..d4b6c1f 100644 > --- a/arch/powerpc/platforms/85xx/smp.c > +++ b/arch/powerpc/platforms/85xx/smp.c > @@ -249,6 +249,13 @@ void __init mpc85xx_smp_init(void) > smp_85xx_ops.cause_ipi = doorbell_cause_ipi; > } > > + /* When running under a hypervisor, we can not modify tb */ > + np = of_find_node_by_path("/hypervisor"); > + if (np) { > + smp_85xx_ops.give_timebase = NULL; > + smp_85xx_ops.take_timebase = NULL; > + } I'm marking this superseded as we now only set give/take_timebase if a guts node is present that corresponds to an SMP SoC. QEMU currently advertises an mpc8544 guts (which is not SMP) and will eventually move to a paravirt device with no guts at all. -Scott