x86/iommu/intel: Fix identity mapping for sandy bridge

With SandyBridge, Intel has changed these Socket PCI devices to
have a class type of "System Peripheral" & "Performance
counter", rather than "HostBridge".

So instead of using a "special" case to detect which devices will
not be doing DMA, use the fact that a device that is not associated
with an IOMMU, will not need an identity map.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Mike Habeck <habeck@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Daniel Rahn <drahn@suse.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-018fywmjs3lmzfyzjlktg8dx@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

drivers/iommu/intel-iommu.c

@@ -48,8 +48,6 @@
 #define ROOT_SIZE		VTD_PAGE_SIZE
 #define CONTEXT_SIZE		VTD_PAGE_SIZE
 
-#define IS_BRIDGE_HOST_DEVICE(pdev) \
-			    ((pdev->class >> 8) == PCI_CLASS_BRIDGE_HOST)
 #define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY)
 #define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA)
 #define IS_AZALIA(pdev) ((pdev)->vendor == 0x8086 && (pdev)->device == 0x3a3e)
@@ -2369,18 +2367,18 @@ static int __init iommu_prepare_static_identity_mapping(int hw)
 		return -EFAULT;
 
 	for_each_pci_dev(pdev) {
-		/* Skip Host/PCI Bridge devices */
-		if (IS_BRIDGE_HOST_DEVICE(pdev))
-			continue;
 		if (iommu_should_identity_map(pdev, 1)) {
-			printk(KERN_INFO "IOMMU: %s identity mapping for device %s\n",
-			       hw ? "hardware" : "software", pci_name(pdev));
-
 			ret = domain_add_dev_info(si_domain, pdev,
-						     hw ? CONTEXT_TT_PASS_THROUGH :
-						     CONTEXT_TT_MULTI_LEVEL);
-			if (ret)
+					     hw ? CONTEXT_TT_PASS_THROUGH :
+						  CONTEXT_TT_MULTI_LEVEL);
+			if (ret) {
+				/* device not associated with an iommu */
+				if (ret == -ENODEV)
+					continue;
 				return ret;
+			}
+			pr_info("IOMMU: %s identity mapping for device %s\n",
+				hw ? "hardware" : "software", pci_name(pdev));
 		}
 	}