From: Don Dutile <ddutile@redhat.com>
Date: Tue, 1 Dec 2009 23:43:07 -0500
Subject: [pci] dmar: check for DMAR at zero BIOS error earlier
Message-id: <4B15AA0B.2080600@redhat.com>
Patchwork-id: 21632
O-Subject: [RHEL5.5 PATCH V2] 4/9: INTEL_IOMMU: check for DMAR at zero BIOS
	error earlier
Bugzilla: 516811 518103
RH-Acked-by: Chris Wright <chrisw@redhat.com>
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>

V2: cleaned up/out space/ident patches that belonged
     in 1/9 or 2/9.

BZ 516727  (BZ 533952 in F12)

Backport of following patch from iommu-2.6.32.git tree:
intel-iommu: Check for 'DMAR at zero' BIOS error earlier.
commit 86cf898e1d0fca245173980e3897580db38569a8

0/9 states build & tests.

Please review & ACK.

- Don
>From 1f28ed45b0ebbea16ace2b0c8f857ff02599934e Mon Sep 17 00:00:00 2001
From: Donald Dutile <ddutile@redhat.com>
Date: Mon, 16 Nov 2009 18:07:24 -0500
Subject: [PATCH 4/9]   INTEL_IOMMU: check for DMAR at zero BIOS error earlier


diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 65513e9..dda81f4 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -175,15 +175,7 @@ dmar_parse_one_drhd(struct acpi_dmar_header *header)
 	int ret = 0;
 
 	drhd = (struct acpi_dmar_hardware_unit *)header;
-	if (!drhd->address) {
-		/* Promote an attitude of violence to a BIOS engineer today */
-		printk(KERN_WARNING PREFIX "Your BIOS is broken; DMAR reported at address zero!\n"
-		     "BIOS vendor: %s; Ver: %s; Product Version: %s\n",
-		     dmi_get_system_info(DMI_BIOS_VENDOR),
-		     dmi_get_system_info(DMI_BIOS_VERSION),
-		     dmi_get_system_info(DMI_PRODUCT_VERSION));
-		return -ENODEV;
-	}
+
 	dmaru = kzalloc(sizeof(*dmaru), GFP_KERNEL);
 	if (!dmaru)
 		return -ENOMEM;
@@ -563,12 +555,52 @@ int __init dmar_table_init(void)
 	return 0;
 }
 
+int __init check_zero_address(void)
+{
+	struct acpi_table_dmar *dmar;
+	struct acpi_dmar_header *entry_header;
+	struct acpi_dmar_hardware_unit *drhd;
+
+	dmar = (struct acpi_table_dmar *)dmar_tbl;
+	entry_header = (struct acpi_dmar_header *)(dmar + 1);
+
+	while (((unsigned long)entry_header) <
+			(((unsigned long)dmar) + dmar_tbl->length)) {
+		/* Avoid looping forever on bad ACPI tables */
+		if (entry_header->length == 0) {
+			printk(KERN_WARNING PREFIX
+				"Invalid 0-length structure\n");
+			return 0;
+		}
+
+		if (entry_header->type == ACPI_DMAR_TYPE_HARDWARE_UNIT) {
+			drhd = (void *)entry_header;
+
+			if (!drhd->address) {
+				/* Promote an attitude of violence to a BIOS engineer today */
+				printk(KERN_WARNING PREFIX 
+					"Your BIOS is broken; DMAR reported at address zero!\n"
+					"BIOS vendor: %s; Ver: %s; Product Version: %s\n",
+					dmi_get_system_info(DMI_BIOS_VENDOR),
+					dmi_get_system_info(DMI_BIOS_VERSION),
+					dmi_get_system_info(DMI_PRODUCT_VERSION));
+				return 0;
+			}
+			break;
+		}
+
+		entry_header = ((void *)entry_header + entry_header->length);
+	}
+	return 1;
+}
+
 void __init detect_intel_iommu(void)
 {
 	int ret;
 
 	ret = dmar_table_detect();
-
+	if (ret)
+		ret = check_zero_address();
 	{
 #ifdef CONFIG_INTR_REMAP
 		struct acpi_table_dmar *dmar;