From: Chris Lalancette <clalance@redhat.com>
Date: Mon, 3 Nov 2008 09:09:01 +0100
Subject: [xen] ia64: backport check_pages_physically_contiguous
Message-id: 490EB19D.3090804@redhat.com
O-Subject: [RHEL5.3 PATCH 1/2]: Backport Xen ia64 check_pages_physically_contiguous
Bugzilla: 463500
RH-Acked-by: Bill Burns <bburns@redhat.com>
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Rik van Riel <riel@redhat.com>

Despite the fact that this patch series is intended to fix i386, this first
patch only ends up touching ia64.  That's to ensure that the swiotlb exhaustion
that Stephen fixed for i386 doesn't happen on ia64.

This patch is a backport of upstream Xen linux-2.6.18-xen.hg c/s 51, 166, and
167.  The main change is in c/s 166; 51 and 167 are just in there for compile fixes.

I would appreciate it if some of the ia64 (Xen or not) people could look at
this; in particular, I want to make sure I haven't done anything crazy, and I
also want to make sure I haven't affected bare-metal with this patch.

diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index 69ff026..57f249b 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -43,6 +43,7 @@
 #include <asm/kexec.h>
 
 #include <asm/acpi-ext.h>
+#include <asm/maddr.h>          /* range_straddles_page_boundary() */
 
 extern int swiotlb_late_init_with_default_size (size_t size);
 
@@ -911,7 +912,7 @@ sba_map_single(struct device *dev, void *addr, size_t size, int dir)
  	** Check if the PCI device can DMA to ptr... if so, just return ptr
  	*/
 	if (likely(pci_addr & ~to_pci_dev(dev)->dma_mask) == 0 &&
-		   !range_straddles_page_boundary(addr, size)) {
+		   !range_straddles_page_boundary(__pa(addr), size)) {
 		/*
  		** Device is bit capable of DMA'ing to the buffer...
 		** just return the PCI address of ptr
diff --git a/arch/ia64/xen/swiotlb.c b/arch/ia64/xen/swiotlb.c
index 047abab..10d16da 100644
--- a/arch/ia64/xen/swiotlb.c
+++ b/arch/ia64/xen/swiotlb.c
@@ -606,7 +606,7 @@ swiotlb_map_single(struct device *hwdev, void *ptr, size_t size, int dir)
 	 * we can safely return the device addr and not worry about bounce
 	 * buffering it.
 	 */
-	if (!range_straddles_page_boundary(ptr, size) &&
+	if (!range_straddles_page_boundary(__pa(ptr), size) &&
 	    !address_needs_mapping(hwdev, dev_addr) && !swiotlb_force)
 		return dev_addr;
 
@@ -775,7 +775,10 @@ swiotlb_map_sg(struct device *hwdev, struct scatterlist *sg, int nelems,
 	for (i = 0; i < nelems; i++, sg++) {
 		addr = SG_ENT_VIRT_ADDRESS(sg);
 		dev_addr = virt_to_bus(addr);
-		if (swiotlb_force || address_needs_mapping(hwdev, dev_addr)) {
+		if (swiotlb_force ||
+		    range_straddles_page_boundary(page_to_pseudophys(sg->page)
+						  + sg->offset, sg->length) ||
+		    address_needs_mapping(hwdev, dev_addr)) {
 			void *map = map_single(hwdev, addr, sg->length, dir);
 			sg->dma_address = virt_to_bus(map);
 			if (!map) {
diff --git a/arch/ia64/xen/xen_dma.c b/arch/ia64/xen/xen_dma.c
index ae97c18..9b277ed 100644
--- a/arch/ia64/xen/xen_dma.c
+++ b/arch/ia64/xen/xen_dma.c
@@ -35,6 +35,41 @@ do {								\
 	}							\
 } while (0)
 
+static int check_pages_physically_contiguous(unsigned long pfn, 
+					     unsigned int offset,
+					     size_t length)
+{
+	unsigned long next_bus;
+	int i;
+	int nr_pages;
+
+	next_bus = pfn_to_mfn_for_dma(pfn);
+	nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT;
+
+	for (i = 1; i < nr_pages; i++) {
+		if (pfn_to_mfn_for_dma(++pfn) != ++next_bus) 
+			return 0;
+	}
+	return 1;
+}
+
+int range_straddles_page_boundary(paddr_t p, size_t size)
+{
+	extern unsigned long *contiguous_bitmap;
+	unsigned long pfn = p >> PAGE_SHIFT;
+	unsigned int offset = p & ~PAGE_MASK;
+
+	if (!is_running_on_xen())
+		return 0;
+
+	if (offset + size <= PAGE_SIZE)
+		return 0;
+	if (test_bit(pfn, contiguous_bitmap))
+		return 0;
+	if (check_pages_physically_contiguous(pfn, offset, size))
+		return 0;
+	return 1;
+}
 
 /*
  * This should be broken out of swiotlb and put in a common place
@@ -62,6 +97,9 @@ xen_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 		sg[i].dma_length  = sg[i].length;
 
 		IOMMU_BUG_ON(address_needs_mapping(dev, sg[i].dma_address));
+		IOMMU_BUG_ON(range_straddles_page_boundary( 
+			page_to_pseudophys(sg[i].page) + sg[i].offset,
+			sg[i].length));
 	}
 
 	return nents;
@@ -131,7 +169,7 @@ xen_map_single(struct device *dev, void *ptr, size_t size,
 {
 	dma_addr_t dma_addr = virt_to_bus(ptr);
 
-	IOMMU_BUG_ON(range_straddles_page_boundary(ptr, size));
+	IOMMU_BUG_ON(range_straddles_page_boundary(__pa(ptr), size));
 	IOMMU_BUG_ON(address_needs_mapping(dev, dma_addr));
 
 	return dma_addr;
diff --git a/include/asm-ia64/dma-mapping.h b/include/asm-ia64/dma-mapping.h
index 533952e..a85a10c 100644
--- a/include/asm-ia64/dma-mapping.h
+++ b/include/asm-ia64/dma-mapping.h
@@ -75,18 +75,4 @@ dma_cache_sync (void *vaddr, size_t size, enum dma_data_direction dir)
 
 #define dma_is_consistent(dma_handle)	(1)	/* all we do is coherent memory... */
 
-#define contiguous_bitmap_init(end_pfn)	((void)end_pfn)
-
-static inline int
-range_straddles_page_boundary(void *p, size_t size)
-{
-	extern unsigned long *contiguous_bitmap;
-
-	if (!is_running_on_xen())
-		return 0;
-
-	return (((((unsigned long)p & ~PAGE_MASK) + size) > PAGE_SIZE) &&
-	        !test_bit(__pa(p) >> PAGE_SHIFT, contiguous_bitmap));
-}
-
 #endif /* _ASM_IA64_DMA_MAPPING_H */
diff --git a/include/asm-ia64/maddr.h b/include/asm-ia64/maddr.h
index 1b05e4c..10c22db 100644
--- a/include/asm-ia64/maddr.h
+++ b/include/asm-ia64/maddr.h
@@ -102,5 +102,14 @@ extern void xen_machphys_update(unsigned long mfn, unsigned long pfn);
 #endif /* CONFIG_VMX_GUEST */
 
 typedef unsigned long maddr_t;	// to compile netback, netfront
+#ifndef _ASM_IA64_SN_TYPES_H /* paddr_t is defined in asm-ia64/sn/types.h */
+typedef unsigned long paddr_t;
+#endif
+
+#ifdef CONFIG_XEN
+int range_straddles_page_boundary(paddr_t p, size_t size);
+#else
+#define range_straddles_page_boundary(addr, size)	(0)
+#endif
 
 #endif /* _ASM_IA64_MADDR_H */
diff --git a/include/asm-ia64/sn/types.h b/include/asm-ia64/sn/types.h
index 8e04ee2..20f13bf 100644
--- a/include/asm-ia64/sn/types.h
+++ b/include/asm-ia64/sn/types.h
@@ -20,7 +20,9 @@ typedef unsigned char	slotid_t;	/* slot (blade) within module */
 typedef unsigned char	slabid_t;	/* slab (asic) within slot */
 typedef u64 nic_t;
 typedef unsigned long iopaddr_t;
+#ifndef _ASM_IA64_MADDR_H /* paddr_t is defined in asm-ia64/maddr.h */
 typedef unsigned long paddr_t;
+#endif
 typedef short cnodeid_t;
 
 #endif /* _ASM_IA64_SN_TYPES_H */