xen/x86: Increase xen_e820_map to E820_X_MAX possible entries

Alex Thorlton · jgross1 · commit 738662c35c49 · 2016-12-09T10:59:08.000+01:00
On systems with sufficiently large e820 tables, and several IOAPICs, it
is possible for the XENMEM_machine_memory_map callback (and its
counterpart, XENMEM_memory_map) to attempt to return an e820 table with
more than 128 entries.  This callback adds entries to the BIOS-provided
e820 table to account for IOAPIC registers, which, on sufficiently large
systems, can result in an e820 table that is too large to copy back into
xen_e820_map.

This change simply increases the size of xen_e820_map to E820_X_MAX to
ensure that there is enough room to store the entire e820 map returned
from this callback.

Signed-off-by: Alex Thorlton &lt;athorlton@sgi.com&gt;
Suggested-by: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Reviewed-by: Juergen Gross &lt;jgross@suse.com&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Juergen Gross &lt;jgross@suse.com&gt;
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
@@ -41,7 +41,7 @@ struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
 unsigned long xen_released_pages;
 
 /* E820 map used during setting up memory. */
-static struct e820entry xen_e820_map[E820MAX] __initdata;
+static struct e820entry xen_e820_map[E820_X_MAX] __initdata;
 static u32 xen_e820_map_entries __initdata;
 
 /*
@@ -750,7 +750,7 @@ char * __init xen_memory_setup(void)
 	max_pfn = min(max_pfn, xen_start_info->nr_pages);
 	mem_end = PFN_PHYS(max_pfn);
 
-	memmap.nr_entries = E820MAX;
+	memmap.nr_entries = ARRAY_SIZE(xen_e820_map);
 	set_xen_guest_handle(memmap.buffer, xen_e820_map);
 
 	op = xen_initial_domain() ?
@@ -923,7 +923,7 @@ char * __init xen_auto_xlated_memory_setup(void)
 	int i;
 	int rc;
 
-	memmap.nr_entries = E820MAX;
+	memmap.nr_entries = ARRAY_SIZE(xen_e820_map);
 	set_xen_guest_handle(memmap.buffer, xen_e820_map);
 
 	rc = HYPERVISOR_memory_op(XENMEM_memory_map, &memmap);
