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Date: Thu, 4 Oct 2012 11:07:46 +0100
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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To: Jan Beulich <JBeulich@suse.com>
CC: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
        Ian Campbell <Ian.Campbell@citrix.com>,
        "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen/xen_initial_domain: check that xen_start_info
 is initialized
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On Thu, 4 Oct 2012, Jan Beulich wrote:
> >>> On 03.10.12 at 19:08, Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>
> wrote:
> > Since commit commit 4c071ee5268f7234c3d084b6093bebccc28cdcba ("arm:
> > initial Xen support") PV on HVM guests can be xen_initial_domain.
> > However PV on HVM guests might have an unitialized xen_start_info, so
> > check before accessing its fields.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> > Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
> > Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > 
> > diff --git a/include/xen/xen.h b/include/xen/xen.h
> > index 9a39ca5..e7101bb 100644
> > --- a/include/xen/xen.h
> > +++ b/include/xen/xen.h
> > @@ -28,7 +28,7 @@ extern enum xen_domain_type xen_domain_type;
> >  #include <asm/xen/hypervisor.h>
> >  
> >  #define xen_initial_domain()	(xen_domain() && \
> > -				 xen_start_info->flags & SIF_INITDOMAIN)
> > +				 xen_start_info && xen_start_info->flags & SIF_INITDOMAIN)
> >  #else  /* !CONFIG_XEN_DOM0 */
> >  #define xen_initial_domain()	(0)
> >  #endif	/* CONFIG_XEN_DOM0 */
> 
> Didn't your other patch statically initialize it?

Yes. Even though both patches can safely coexist, I wrote this one as an
alternative solution.