[PATCH] swiotlb: use swiotlb_alloc_boot to allocate emergency pool

[Jeremy Fitzhardinge <jeremy@goop.org>]

Impact: bugfix

Also fix xen_swiotlb_fixup() to deal with sub-slab-sized allocations.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 0de836d..e8df499 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -202,7 +202,8 @@ swiotlb_init_with_default_size(size_t default_size)
 	/*
 	 * Get the overflow emergency buffer
 	 */
-	io_tlb_overflow_buffer = alloc_bootmem_low(io_tlb_overflow);
+	io_tlb_overflow_buffer = swiotlb_alloc_boot(io_tlb_overflow,
+						    io_tlb_overflow >> IO_TLB_SHIFT);
 	if (!io_tlb_overflow_buffer)
 		panic("Cannot allocate SWIOTLB overflow buffer!\n");
 
diff --git a/drivers/pci/xen-iommu.c b/drivers/pci/xen-iommu.c
index 9ce1599..5775691 100644
--- a/drivers/pci/xen-iommu.c
+++ b/drivers/pci/xen-iommu.c
@@ -47,16 +47,22 @@ void xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
 		buf, size);
 
 	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
-	for (i = 0; i < nslabs; i += IO_TLB_SEGSIZE) {
+
+	i = 0;
+	do {
+		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
+
 		do {
 			rc = xen_create_contiguous_region(
 				(unsigned long)buf + (i << IO_TLB_SHIFT),
-				get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT),
+				get_order(slabs << IO_TLB_SHIFT),
 				dma_bits);
 		} while (rc && dma_bits++ < max_dma_bits);
 		if (rc)
 			panic(KERN_ERR "xen_create_contiguous_region failed\n");
-	}
+
+		i += slabs;
+	} while(i < nslabs);
 }
 
 int xen_wants_swiotlb(void)