From: Don Dugger <ddugger@redhat.com>
Date: Tue, 23 Feb 2010 20:31:37 -0500
Subject: [xen] vtd: ignore unknown DMAR entries
Message-id: <201002232031.o1NKVbTv008403@sobek.n0ano.com>
Patchwork-id: 23412
O-Subject: [RHEL 5.5 PATCH V2] BZ 563900: xen: Ignore unknown DMAR entries
Bugzilla: 563900
RH-Acked-by: Don Dutile <ddutile@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Andrew Jones <drjones@redhat.com>

Currently the system fails the VTd initialization when it encounters an
unknown DMAR entry which is a little excessive.  This simple one line change
causes the system to print out a warning message and then continue when
it encounters an unknown entry.

This fix is required in order to enable VTd on a Tylersburg-EX system.
The more complete fix is to backport 2 upstream changesets (19810 and
19929) but that is too invasive for 5.5, those changes will be targeted
for RHEL 5.6.

Upstream Status - NA (see above)

Brew build - http://brewweb.devel.redhat.com/brew/taskinfo?taskID=2276748

Testing - Tested on my Tylersberg-EP system (which doesn't have the unknown
DMAR entry) and the system works fine, including VTd assignment to an
HVM guest.  More testing will be available tomorrow from the PRC team
but I wanted to get the patch out as soon as possible.

Signed-off-by: Don Dugger <donald.d.dugger@intel.com>
---
 drivers/passthrough/vtd/dmar.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/drivers/passthrough/vtd/dmar.c b/drivers/passthrough/vtd/dmar.c
index 63e4e0b..f3f2c5f 100644
--- a/drivers/passthrough/vtd/dmar.c
+++ b/drivers/passthrough/vtd/dmar.c
@@ -486,8 +486,11 @@ static int __init acpi_parse_dmar(unsigned long phys_addr,
             ret = acpi_parse_one_atsr(entry_header);
             break;
         default:
+	    /*
+	     *  Don't panic on an unknown table, just print a warning
+	     *    and continue
+	     */
             dprintk(XENLOG_WARNING VTDPREFIX, "Unknown DMAR structure type\n");
-            ret = -EINVAL;
             break;
         }
         if ( ret )