Commit 7cb31b75 authored Jan 27, 2011 by Stefano Stabellini Committed by Konrad Rzeszutek Wilk Jan 27, 2011

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>

parent cf04d120

arch/x86/xen/setup.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -179,8 +179,13 @@ char * __init xen_memory_setup(void)
		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);

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