[PATCH] x86_64: no_iommu removal in pci-gart.c

In previous versions of pci-gart.c, no_iommu was used to determine if IOMMU was
disabled in the GART DMA mapping functions.  This changed in 2.6.16 and now
gart_xxx() functions are only called if gart is enabled.  Therefore, uses of
no_iommu in the GART code are no longer necessary and can be removed.

Also, it removes double deceleration of no_iommu and force_iommu in pci.h and
proto.h, by removing the deceleration in pci.h.

Lastly, end_pfn off by one error.

Tested (along with patch 1/2) on dual opteron with gart enabled, iommu=soft,
and iommu=off.

Signed-off-by: Jon Mason <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

@@ -248,7 +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 >= MAX_DMA32_PFN) ||
+	} else if ((!no_iommu && end_pfn > MAX_DMA32_PFN) ||
 		   force_iommu ||
 		   valid_agp ||
 		   fallback_aper_force) { 

arch/x86_64/kernel/pci-gart.c

@@ -228,11 +228,6 @@ static inline int need_iommu(struct device *dev, unsigned long addr, size_t size
 	int mmu = high;
 	if (force_iommu) 
 		mmu = 1; 
-	if (no_iommu) { 
-		if (high) 
-			panic("PCI-DMA: high address but no IOMMU.\n"); 
-		mmu = 0; 
-	} 	
 	return mmu; 
 }
 
@@ -241,11 +236,6 @@ static inline int nonforced_iommu(struct device *dev, unsigned long addr, size_t
 	u64 mask = *dev->dma_mask;
 	int high = addr + size >= mask;
 	int mmu = high;
-	if (no_iommu) { 
-		if (high) 
-			panic("PCI-DMA: high address but no IOMMU.\n"); 
-		mmu = 0; 
-	} 	
 	return mmu; 
 }
 
@@ -310,7 +300,7 @@ void gart_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, int di
 
 	for (i = 0; i < nents; i++) {
 		struct scatterlist *s = &sg[i];
-		if (!s->dma_length)
+		if (!s->dma_length || !s->length)
 			break;
 		dma_unmap_single(dev, s->dma_address, s->dma_length, dir);
 	}
@@ -364,6 +354,7 @@ static int __dma_map_cont(struct scatterlist *sg, int start, int stopat,
 		
 		BUG_ON(i > start && s->offset);
 		if (i == start) {
+			*sout = *s; 
 			sout->dma_address = iommu_bus_base;
 			sout->dma_address += iommu_page*PAGE_SIZE + s->offset;
 			sout->dma_length = s->length;
@@ -390,6 +381,7 @@ static inline int dma_map_cont(struct scatterlist *sg, int start, int stopat,
 {
 	if (!need) { 
 		BUG_ON(stopat - start != 1);
+		*sout = sg[start]; 
 		sout->dma_length = sg[start].length; 
 		return 0;
 	} 
@@ -632,17 +624,13 @@ static int __init pci_iommu_init(void)
 		(agp_copy_info(agp_bridge, &info) < 0);
 #endif	
 
-	if (swiotlb) { 
-		no_iommu = 1;
+	if (swiotlb)
 		return -1; 
-	} 
-	
+
 	if (no_iommu ||
 	    (!force_iommu && end_pfn <= MAX_DMA32_PFN) ||
 	    !iommu_aperture ||
 	    (no_agp && init_k8_gatt(&info) < 0)) {
-		no_iommu = 1;
-		no_iommu_init();
 		printk(KERN_INFO "PCI-DMA: Disabling IOMMU.\n");
 		if (end_pfn > MAX_DMA32_PFN) {
 			printk(KERN_ERR "WARNING more than 4GB of memory "

include/asm-x86_64/pci.h

@@ -19,8 +19,6 @@ extern unsigned int pcibios_assign_all_busses(void);
 #endif
 #define pcibios_scan_all_fns(a, b)	0
 
-extern int no_iommu, force_iommu;
-
 extern unsigned long pci_mem_start;
 #define PCIBIOS_MIN_IO		0x1000
 #define PCIBIOS_MIN_MEM		(pci_mem_start)