From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 06/10] xen/setup: Only set identity mapping in E820 regions when privileged. Date: Tue, 21 Dec 2010 14:37:01 -0800 Message-ID: <4D112C0D.6060400@goop.org> References: <1292967460-15709-1-git-send-email-konrad.wilk@oracle.com> <1292967460-15709-7-git-send-email-konrad.wilk@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1292967460-15709-7-git-send-email-konrad.wilk@oracle.com> Sender: linux-kernel-owner@vger.kernel.org To: Konrad Rzeszutek Wilk Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, Jan Beulich , xen-devel@lists.xensource.com, Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org On 12/21/2010 01:37 PM, Konrad Rzeszutek Wilk wrote: > We do not want to set the identity mapping on E820 reserved > regions when running as PV. This is b/c the 0->ISA_END_ADDRESS region > would be considered identity and we would try to read DMI information > and fail (since the pfn_to_mfn(mfn)==pfn) under PV guests. > > Signed-off-by: Konrad Rzeszutek Wilk > --- > arch/x86/xen/setup.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c > index 752c865..34fb906 100644 > --- a/arch/x86/xen/setup.c > +++ b/arch/x86/xen/setup.c > @@ -160,7 +160,7 @@ static unsigned long __init xen_set_identity(const struct e820map *e820) > if (end < start) > continue; > > - if (e820->map[i].type != E820_RAM) { > + if (xen_initial_domain() && e820->map[i].type != E820_RAM) { > for (pfn = PFN_UP(start); pfn < PFN_DOWN(end); pfn++) > set_phys_to_machine(pfn, pfn); > identity += pfn - PFN_UP(start); So you're relying on the fact that the ISA area is the only non-RAM e820 entry in domU? I think it would be better to do a specific exclusion for the ISA area rather than this. J