From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from TX2EHSOBE004.bigfish.com (tx2ehsobe001.messaging.microsoft.com [65.55.88.11]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 0256F1007DA for ; Sat, 3 Mar 2012 03:21:30 +1100 (EST) Date: Fri, 2 Mar 2012 10:20:58 -0600 From: Scott Wood To: Alexander Graf Subject: Re: [PATCH] PPC: Don't sync timebase when inside VM Message-ID: <20120302162058.GA24552@schlenkerla.am.freescale.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; > + } > + > smp_ops = &smp_85xx_ops; Again, for 85xx we should *never* sync the timebase in the kernel, hypervisor or no. -Scott