xen/e820: Guard against E820_RAM not having page-aligned size or start.
Under Dell Inspiron 1525, and Intel SandyBridge SDP's the
BIOS e820 RAM is not page-aligned:
[ 0.000000] Xen: 0000000000100000 - 00000000df66d800 (usable)
We were not handling that and ended up setting up a pagetable
that included up to df66e000 with the disastrous effect that when
memset(NODE_DATA(nodeid), 0, sizeof(pg_data_t));
tried to clear the page it would crash at the 2K mark.
Initially reported by Michael Young @
http://lists.xensource.com/archives/html/xen-devel/2011-01/msg00108.html
The fix is to page-align the size and also take into consideration
the start of the E820 (in case that is not page-aligned either). This
fixes the bootup failure on those affected machines.
This patch is a rework of the Micheal A Young initial patch and
considers the case if the start is not page-aligned.
Reported-by: Michael A Young <m.a.young@durham.ac.uk>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Michael A Young <m.a.young@durham.ac.uk>
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index b5a7f92..75bdf2a 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -179,8 +179,13 @@
e820.nr_map = 0;
xen_extra_mem_start = mem_end;
for (i = 0; i < memmap.nr_entries; i++) {
- unsigned long long end = map[i].addr + map[i].size;
+ unsigned long long end;
+ /* Guard against non-page aligned E820 entries. */
+ if (map[i].type == E820_RAM)
+ map[i].size -= (map[i].size + map[i].addr) % PAGE_SIZE;
+
+ end = map[i].addr + map[i].size;
if (map[i].type == E820_RAM && end > mem_end) {
/* RAM off the end - may be partially included */
u64 delta = min(map[i].size, end - mem_end);
