bitkeeper revision 1.1108.33.39 (410f5c80HHs32Qoh3S41tB5KdiU-uA)

Fix pci_alloc_consistent() to always return contiguous 
machine memory.

2 files changed, 48 insertions, 5 deletions

diff --git a/linux-2.4.26-xen-sparse/arch/xen/kernel/pci-dma.c b/linux-2.4.26-xen-sparse/arch/xen/kernel/pci-dma.c
index dd8842719e..e841ba86ca 100644
--- a/linux-2.4.26-xen-sparse/arch/xen/kernel/pci-dma.c
+++ b/linux-2.4.26-xen-sparse/arch/xen/kernel/pci-dma.c
@@ -18,15 +18,59 @@ void *pci_alloc_consistent(struct pci_dev *hwdev, size_t size,
 {
 	void *ret;
 	int gfp = GFP_ATOMIC;
+	unsigned int order = get_order(size);
+	unsigned long vstart;
 
 	if (hwdev == NULL || ((u32)hwdev->dma_mask < 0xffffffff))
 		gfp |= GFP_DMA;
-	ret = (void *)__get_free_pages(gfp, get_order(size));
 
-	if (ret != NULL) {
-		memset(ret, 0, size);
-		*dma_handle = virt_to_bus(ret);
+	ret = (void *)vstart = __get_free_pages(gfp, order);
+	if (ret == NULL)
+		return ret;
+
+	/*
+	 * Ensure multi-page extents are contiguous in machine memory.
+	 * This code could be cleaned up some, and the number of
+	 * hypercalls reduced.
+	 */
+	if (size > PAGE_SIZE) {
+		pgd_t         *pgd; 
+		pmd_t         *pmd;
+		pte_t         *pte;
+		unsigned long  pfn, i;
+		/* 1. Zap current PTEs, giving away the underlying pages. */
+		for (i = 0; i < (1<<order); i++) {
+			pgd = pgd_offset_k(   (vstart + (i*PAGE_SIZE)));
+			pmd = pmd_offset(pgd, (vstart + (i*PAGE_SIZE)));
+			pte = pte_offset(pmd, (vstart + (i*PAGE_SIZE)));
+			pfn = pte->pte_low >> PAGE_SHIFT;
+			queue_l1_entry_update(pte, 0);
+			flush_page_update_queue();
+			if (HYPERVISOR_dom_mem_op(MEMOP_decrease_reservation, 
+				&pfn, 1, 0) != 1) BUG();
+		}
+		/* 2. Get a new contiguous memory extent. */
+		if (HYPERVISOR_dom_mem_op(MEMOP_increase_reservation,
+			&pfn, 1, order) != 1) BUG();
+		/* 3. Map the new extent in place of old pages. */
+		for (i = 0; i < (1<<order); i++) {
+			pgd = pgd_offset_k(   (vstart + (i*PAGE_SIZE)));
+			pmd = pmd_offset(pgd, (vstart + (i*PAGE_SIZE)));
+			pte = pte_offset(pmd, (vstart + (i*PAGE_SIZE)));
+			queue_l1_entry_update(pte, 
+				((pfn+i)<<PAGE_SHIFT)|__PAGE_KERNEL);
+			queue_machphys_update(pfn+i,
+				(__pa(ret)>>PAGE_SHIFT)+i);
+			phys_to_machine_mapping[(__pa(ret)>>PAGE_SHIFT)+i] =
+				pfn+i;
+                        flush_page_update_queue();
+		}
+		flush_page_update_queue();
 	}
+
+	memset(ret, 0, size);
+	*dma_handle = virt_to_bus(ret);
+
 	return ret;
 }
 
diff --git a/linux-2.4.26-xen-sparse/mkbuildtree b/linux-2.4.26-xen-sparse/mkbuildtree
index 3dd6515b88..bb06d9b978 100755
--- a/linux-2.4.26-xen-sparse/mkbuildtree
+++ b/linux-2.4.26-xen-sparse/mkbuildtree
@@ -213,7 +213,6 @@ ln -sf ../../${LINUX_26}/include/asm-xen/xen_proc.h
 cd ${AD}/arch/xen/kernel
 ln -sf ../../i386/kernel/i387.c
 ln -sf ../../i386/kernel/init_task.c
-ln -sf ../../i386/kernel/pci-dma.c
 ln -sf ../../i386/kernel/pci-i386.c
 ln -sf ../../i386/kernel/pci-i386.h
 ln -sf ../../i386/kernel/ptrace.c