diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 1093f80..b2c7179 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -173,9 +173,21 @@
 	domid_t domid = DOMID_SELF;
 	int ret;
 
-	ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
-	if (ret > 0)
-		max_pages = ret;
+	/*
+	 * For the initial domain we use the maximum reservation as
+	 * the maximum page.
+	 *
+	 * For guest domains the current maximum reservation reflects
+	 * the current maximum rather than the static maximum. In this
+	 * case the e820 map provided to us will cover the static
+	 * maximum region.
+	 */
+	if (xen_initial_domain()) {
+		ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
+		if (ret > 0)
+			max_pages = ret;
+	}
+
 	return min(max_pages, MAX_DOMAIN_PAGES);
 }
 
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 8e964b9..284798a 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -166,7 +166,7 @@
 	/*
 	 * Get IO TLB memory from any location.
 	 */
-	xen_io_tlb_start = alloc_bootmem(bytes);
+	xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
 	if (!xen_io_tlb_start) {
 		m = "Cannot allocate Xen-SWIOTLB buffer!\n";
 		goto error;
@@ -179,7 +179,7 @@
 			       bytes,
 			       xen_io_tlb_nslabs);
 	if (rc) {
-		free_bootmem(__pa(xen_io_tlb_start), bytes);
+		free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
 		m = "Failed to get contiguous memory for DMA from Xen!\n"\
 		    "You either: don't have the permissions, do not have"\
 		    " enough free memory under 4GB, or the hypervisor memory"\