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

Noticed by Jon Mason.

Cc: jdmason@us.ibm.com

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/arch/x86_64/kernel/aperture.c
===================================================================
--- linux.orig/arch/x86_64/kernel/aperture.c
+++ linux/arch/x86_64/kernel/aperture.c
@@ -247,7 +247,7 @@ 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-1) >= 0xffffffff>>PAGE_SHIFT) ||
 		   force_iommu ||
 		   valid_agp ||
 		   fallback_aper_force) { 
Index: linux/arch/x86_64/kernel/pci-gart.c
===================================================================
--- linux.orig/arch/x86_64/kernel/pci-gart.c
+++ linux/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"); 
Index: linux/arch/x86_64/mm/init.c
===================================================================
--- linux.orig/arch/x86_64/mm/init.c
+++ linux/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();