[VTD][QUIRK] turn off Sandybridge IGD quirk by default

Turn off Sandybridge IGD quirk by default until potential issues such
as MMIO register conflict with OS device driver and proper locking in
preamble and postamble functions are addressed.

Signed-off-by: Allen Kay <allen.m.kay@intel.com>

diff --git a/xen/drivers/passthrough/vtd/quirks.c b/xen/drivers/passthrough/vtd/quirks.c
index f6a7ac029425368234e64662cdacdba12960422e..f4f60605767bfab2d0dbcb111df9a5eff348603d 100644 (file)
--- a/xen/drivers/passthrough/vtd/quirks.c
+++ b/xen/drivers/passthrough/vtd/quirks.c
@@ -217,10 +217,15 @@ static void snb_vtd_ops_postamble(struct iommu* iommu)
 /*
  * call before VT-d translation enable and IOTLB flush operations.
  */
+
+static int snb_igd_quirk;
+boolean_param("snb_igd_quirk", snb_igd_quirk);
+
 void vtd_ops_preamble_quirk(struct iommu* iommu)
 {
     cantiga_vtd_ops_preamble(iommu);
-    snb_vtd_ops_preamble(iommu);
+    if ( snb_igd_quirk )
+        snb_vtd_ops_preamble(iommu);
 }
 
 /*
@@ -228,7 +233,8 @@ void vtd_ops_preamble_quirk(struct iommu* iommu)
  */
 void vtd_ops_postamble_quirk(struct iommu* iommu)
 {
-    snb_vtd_ops_postamble(iommu);
+    if ( snb_igd_quirk )
+        snb_vtd_ops_postamble(iommu);
 }
 
 /* initialize platform identification flags */