From ca8642f606ce22de23bae08a5044067f98de855b Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Wed, 11 Jan 2006 22:44:27 +0100
Subject: [PATCH] [PATCH] x86_64: Fix off by one in IOMMU check

Fix off by one when checking if the machine has enougn memory to need IOMMU
This caused the IOMMUs to be needlessly enabled for mem=4G

Based on a patch from Jon Mason

Signed-off-by: jdmason@us.ibm.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 arch/x86_64/kernel/aperture.c | 3 ++-
 arch/x86_64/kernel/io_apic.c  | 3 ++-
 arch/x86_64/kernel/pci-gart.c | 2 +-
 arch/x86_64/mm/init.c         | 2 +-
 4 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86_64/kernel/aperture.c b/arch/x86_64/kernel/aperture.c
index c7f4fdd..e4e2b7d 100644
--- a/arch/x86_64/kernel/aperture.c
+++ b/arch/x86_64/kernel/aperture.c
@@ -23,6 +23,7 @@
 #include <asm/io.h>
 #include <asm/proto.h>
 #include <asm/pci-direct.h>
+#include <asm/dma.h>
 
 int iommu_aperture;
 int iommu_aperture_disabled __initdata = 0;
@@ -247,7 +248,7 @@ void __init iommu_hole_init(void)
 		/* Got the aperture from the AGP bridge */
 	} else if (swiotlb && !valid_agp) {
 		/* Do nothing */
-	} else if ((!no_iommu && end_pfn >= 0xffffffff>>PAGE_SHIFT) ||
+	} else if ((!no_iommu && end_pfn >= MAX_DMA32_PFN) ||
 		   force_iommu ||
 		   valid_agp ||
 		   fallback_aper_force) { 
diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index bdc5899..83ea86e0 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -37,6 +37,7 @@
 #include <asm/proto.h>
 #include <asm/mach_apic.h>
 #include <asm/acpi.h>
+#include <asm/dma.h>
 
 #define __apicdebuginit  __init
 
@@ -281,7 +282,7 @@ void __init check_ioapic(void)
 				switch (vendor) { 
 				case PCI_VENDOR_ID_VIA:
 #ifdef CONFIG_GART_IOMMU
-					if ((end_pfn >= (0xffffffff>>PAGE_SHIFT) ||
+					if ((end_pfn > MAX_DMA32_PFN ||
 					     force_iommu) &&
 					    !iommu_aperture_allowed) {
 						printk(KERN_INFO
diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
index 2b865c9..116e00f1 100644
--- a/arch/x86_64/kernel/pci-gart.c
+++ b/arch/x86_64/kernel/pci-gart.c
@@ -804,7 +804,7 @@ static int __init pci_iommu_init(void)
 	} 
 	
 	if (no_iommu ||
-	    (!force_iommu && end_pfn < 0xffffffff>>PAGE_SHIFT) ||
+	    (!force_iommu && (end_pfn-1) < 0xffffffff>>PAGE_SHIFT) ||
 	    !iommu_aperture ||
 	    (no_agp && init_k8_gatt(&info) < 0)) {
 		printk(KERN_INFO "PCI-DMA: Disabling IOMMU.\n"); 
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 1faae5f..5337ca0 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -424,7 +424,7 @@ void __init mem_init(void)
 
 #ifdef CONFIG_SWIOTLB
 	if (!iommu_aperture &&
-	    (end_pfn >= 0xffffffff>>PAGE_SHIFT || force_iommu))
+	    ((end_pfn-1) >= 0xffffffff>>PAGE_SHIFT || force_iommu))
 	       swiotlb = 1;
 	if (swiotlb)
 		swiotlb_init();	
-- 
2.7.4