intel-iommu: Abort IOMMU setup for igfx if BIOS gave no shadow GTT space

Yet another BIOS bug; Lenovo this time (X201). Red Hat bug #593516.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/pci/intel-iommu.c

@@ -3761,6 +3761,23 @@ static void __devinit quirk_iommu_rwbf(struct pci_dev *dev)
 
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_rwbf);
 
+static void __devinit quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
+{
+	unsigned short ggc;
+
+	if (pci_read_config_word(dev, 0x52, &ggc))
+		return;
+
+	if (!(ggc & 0x800)) {
+		printk(KERN_INFO "DMAR: BIOS has allocated no shadow GTT; disabling IOMMU for graphics\n");
+		dmar_map_gfx = 0;
+	}
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0044, quirk_calpella_no_shadow_gtt);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0062, quirk_calpella_no_shadow_gtt);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x006a, quirk_calpella_no_shadow_gtt);
+
 /* On Tylersburg chipsets, some BIOSes have been known to enable the
    ISOCH DMAR unit for the Azalia sound device, but not give it any
    TLB entries, which causes it to deadlock. Check for that.  We do