From: Jarod Wilson <jwilson@redhat.com>
Date: Tue, 21 Aug 2007 22:12:53 -0400
Subject: [xen] ia64: make ioremapping work
Message-id: 46CB9BA5.4030109@redhat.com
O-Subject: [RHEL5.2 PATCH] make ioremapping work on ia64 xen kernels
Bugzilla: 240006

Bugzilla
--------
#252399: ioremap patchset makes kernel-xen non-bootable on some ia64
hardware

Description
-----------
The ioremapping patch set we initially pulled into kernel 2.6.18-40.el5,
but reverted in 2.6.18-41.el5, adds the ability for mmap requests to be
validated, and if need be, remapped to another memory location. This
change was necessary to make X function on a number of newer ia64
systems. However, these changes made the xen kernel trigger a machine
check on many of the same systems (predominantly those from HP).

The crux of the problem is that we need the value of "size" for the xen
ioremap hypercall, but we rounded it up to full pages before passing it
to xen. If we use a different variable "page_size" for the rounded-up
value, rather than clobbering "size", the xen kernels function with the
ioremapping changes included.

If at all possible, I know HP, Fujitsu, Hitachi and Intel would all like
to see us revisit the ioremapping patches + this for 5.1 so X won't be
busted on their newer systems, but if not, hey, we're getting a good
jump start on 5.2...

Testing
-------
Tested successfully on a number of HP systems that were failing with the
prior ioremap patchset. Further testing across a wider array of systems
forthcoming.

Upstream status
---------------
The patch originates from Bjorn Helgaas at Hewlett-Packard, who wrote
the ioremapping patches in the first place (which went into 2.6.19), and
Bjorn should be sending them along upstream himself before too much longer.

--
Jarod Wilson
jwilson@redhat.com

Preserve "size", which is used if we can't use page table mappings.

Acked-by: Doug Chapman <dchapman@redhat.com>
Nacked-by: "Stephen C. Tweedie" <sct@redhat.com>
Acked-by: "Stephen C. Tweedie" <sct@redhat.com>

diff --git a/arch/ia64/mm/ioremap.c b/arch/ia64/mm/ioremap.c
index 7e876e0..5568d56 100644
--- a/arch/ia64/mm/ioremap.c
+++ b/arch/ia64/mm/ioremap.c
@@ -35,7 +35,7 @@ ioremap (unsigned long phys_addr, unsigned long size)
 	pgprot_t prot;
 	u64 attr;
 	unsigned long gran_base, gran_size;
-	unsigned long page_base;
+	unsigned long page_base, page_size;
 
 	/*
 	 * For things in kern_memmap, we must use the same attribute
@@ -64,8 +64,8 @@ ioremap (unsigned long phys_addr, unsigned long size)
 	 * instead.
 	 */
 	page_base = phys_addr & PAGE_MASK;
-	size = PAGE_ALIGN(phys_addr + size) - page_base;
-	if (efi_mem_attribute(page_base, size) & EFI_MEMORY_WB) {
+	page_size = PAGE_ALIGN(phys_addr + size) - page_base;
+	if (efi_mem_attribute(page_base, page_size) & EFI_MEMORY_WB) {
 		prot = PAGE_KERNEL;
 
 		/*
@@ -77,14 +77,14 @@ ioremap (unsigned long phys_addr, unsigned long size)
 		/*
 		 * Ok, go for it..
 		 */
-		area = get_vm_area(size, VM_IOREMAP);
+		area = get_vm_area(page_size, VM_IOREMAP);
 		if (!area)
 			return NULL;
 
 		area->phys_addr = phys_addr;
 		addr = (void __iomem *) area->addr;
 		if (ioremap_page_range((unsigned long) addr,
-				(unsigned long) addr + size, phys_addr, prot)) {
+				(unsigned long) addr + page_size, phys_addr, prot)) {
 			vunmap((void __force *) addr);
 			return NULL;
 		}