[Xen-changelog] [xen-3.4-testing] VT-d: prevent dom0 to use VT-d HW

["Xen patchbot-3.4-testing" <patchbot-3.4-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1254409055 -3600
# Node ID 7eaa798200f679148fbd9d74b3fd958b5f8b7079
# Parent  a5251bffea427aad74592065dc7fff99fe74f5ce
VT-d: prevent dom0 to use VT-d HW

pv-ops dom0 contains Linux upstream VT-d driver, and will go to enable
it when VT-d is set in kernel config file. It should not enable VT-d
in dom0.

Currently it already zaps ACPI DMAR signature to prevents dom0 using
VT-d HW when VT-d is enabled for Xen. But when VT-d is not enabled for
Xen, and VT-d is set in pv-ops kernel config file, pv-ops dom0 will go
to enable it. This will results in pv-ops dom0 booting failure. This
patch prevents dom0 to use VT-d HW whether VT-d is enabled or disabled
for Xen.

Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
xen-unstable changeset:   20181:1c406a505fc0
xen-unstable date:        Tue Sep 08 15:10:31 2009 +0100
---
 xen/drivers/passthrough/vtd/dmar.c |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff -r a5251bffea42 -r 7eaa798200f6 xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c        Thu Oct 01 15:57:05 2009 +0100
+++ b/xen/drivers/passthrough/vtd/dmar.c        Thu Oct 01 15:57:35 2009 +0100
@@ -471,6 +471,12 @@ static int __init acpi_parse_dmar(struct
 
     dmar = (struct acpi_table_dmar *)table;
 
+    if ( !iommu_enabled )
+    {
+        ret = -EINVAL;
+        goto out;
+    }
+
     if ( !dmar->width )
     {
         dprintk(XENLOG_WARNING VTDPREFIX, "Zero: Invalid DMAR width\n");
@@ -513,9 +519,6 @@ static int __init acpi_parse_dmar(struct
         entry_header = ((void *)entry_header + entry_header->length);
     }
 
-    /* Zap APCI DMAR signature to prevent dom0 using vt-d HW. */
-    dmar->header.signature[0] = '\0';
-
     if ( ret )
     {
         if ( force_iommu )
@@ -529,6 +532,9 @@ static int __init acpi_parse_dmar(struct
         }
     }
 
+out:
+    /* Zap ACPI DMAR signature to prevent dom0 using vt-d HW. */
+    dmar->header.signature[0] = '\0';
     return ret;
 }
 
@@ -549,9 +555,6 @@ int acpi_dmar_init(void)
     if ( force_iommu )
         iommu_enabled = 1;
 
-    if ( !iommu_enabled )
-        goto fail;
-
     rc = parse_dmar_table(acpi_parse_dmar);
     if ( rc )
         goto fail;

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog