From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964895Ab2JCPt7 (ORCPT ); Wed, 3 Oct 2012 11:49:59 -0400 Received: from smtp.ctxuk.citrix.com ([62.200.22.115]:42340 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932427Ab2JCPt6 (ORCPT ); Wed, 3 Oct 2012 11:49:58 -0400 X-IronPort-AV: E=Sophos;i="4.80,528,1344211200"; d="scan'208";a="14920059" Date: Wed, 3 Oct 2012 16:48:57 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Konrad Rzeszutek Wilk CC: Stefano Stabellini , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] xen: point xen_start_info to a dummy struct for PV on HVM guests In-Reply-To: <20121003134323.GA31270@phenom.dumpdata.com> Message-ID: References: <20121003134323.GA31270@phenom.dumpdata.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 3 Oct 2012, Konrad Rzeszutek Wilk wrote: > On Wed, Oct 03, 2012 at 02:37:53PM +0100, Stefano Stabellini wrote: > > PV on HVM guests don't have a start_info page mapped by Xen, so > > xen_start_info is just NULL for them. > > That is problem because other parts of the code expect xen_start_info to > > point to something valid, for example xen_initial_domain() is defined as > > follow: > > > > #define xen_initial_domain() (xen_domain() && \ > > xen_start_info->flags & SIF_INITDOMAIN) > > > > .. introduced by commit 4c071ee5268f7234c3d084b6093bebccc28cdcba > ("arm: initial Xen support) > > > > > Allocate a dummy start_info struct and point xen_start_info to it, as we > > do on ARM. > > This is not going to change things for PV guests because > > xen_start_info is set by arch/x86/xen/xen-head.S:startup_xen. > > > > Signed-off-by: Stefano Stabellini > > Reported-by: Konrad Rzeszutek Wilk > > > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > > index bf788d3..5f242cb 100644 > > --- a/arch/x86/xen/enlighten.c > > +++ b/arch/x86/xen/enlighten.c > > @@ -96,7 +96,8 @@ EXPORT_SYMBOL(machine_to_phys_mapping); > > unsigned long machine_to_phys_nr; > > EXPORT_SYMBOL(machine_to_phys_nr); > > > > -struct start_info *xen_start_info; > > +static struct start_info _xen_start_info; > > And lets change that to > 'xen_dummy_start_info' to keep in sync with the other dummy one. > > And also add a commnt: > > /* > * Since 'xen_initial_domain' dereferences the xen_start_info we need > * a dummy structure filled with zeros (for PVHVM guests which initialize > * this late). For PV guests we do not have to worry about this as the first > * few instructions (startup_xen) set it properly. > */ I agree with all the changes, I'll repost soon > > +struct start_info *xen_start_info = &_xen_start_info; > > EXPORT_SYMBOL_GPL(xen_start_info); > > > > struct shared_info xen_dummy_shared_info; >