PCI/iommu: blacklist DMAR on Intel G31/G33 chipsets

Some BIOSes (the Intel DG33BU, for example) wrongly claim to have DMAR
when they don't. Avoid the resulting crashes when it doesn't work as
expected.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 8d0e60ac849c..c3edcdc08e72 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -2348,11 +2348,34 @@ static void __init iommu_exit_mempool(void)
 
 }
 
+static int blacklist_iommu(const struct dmi_system_id *id)
+{
+        printk(KERN_INFO "%s detected; disabling IOMMU\n",
+               id->ident);
+        dmar_disabled = 1;
+        return 0;
+}
+
+static struct dmi_system_id __initdata intel_iommu_dmi_table[] = {
+        {       /* Some DG33BU BIOS revisions advertised non-existent VT-d */
+                .callback = blacklist_iommu,
+                .ident = "Intel DG33BU",
+                {       DMI_MATCH(DMI_BOARD_VENDOR, "Intel Corporation"),
+                        DMI_MATCH(DMI_BOARD_NAME, "DG33BU"),
+                }
+        },
+        { }
+};
+
+
 void __init detect_intel_iommu(void)
 {
         if (swiotlb || no_iommu || iommu_detected || dmar_disabled)
                 return;
         if (early_dmar_detect()) {
+                dmi_check_system(intel_iommu_dmi_table);
+                if (dmar_disabled)
+                        return;
                 iommu_detected = 1;
         }
 }