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-rw-r--r--arch/x86/xen/setup.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index b1dbdaa23ecc..769c4b01fa32 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -118,16 +118,18 @@ static unsigned long __init xen_return_unused_memory(unsigned long max_pfn,
const struct e820map *e820)
{
phys_addr_t max_addr = PFN_PHYS(max_pfn);
- phys_addr_t last_end = 0;
+ phys_addr_t last_end = ISA_END_ADDRESS;
unsigned long released = 0;
int i;
+ /* Free any unused memory above the low 1Mbyte. */
for (i = 0; i < e820->nr_map && last_end < max_addr; i++) {
phys_addr_t end = e820->map[i].addr;
end = min(max_addr, end);
- released += xen_release_chunk(last_end, end);
- last_end = e820->map[i].addr + e820->map[i].size;
+ if (last_end < end)
+ released += xen_release_chunk(last_end, end);
+ last_end = max(last_end, e820->map[i].addr + e820->map[i].size);
}
if (last_end < max_addr)
@@ -164,6 +166,7 @@ char * __init xen_memory_setup(void)
XENMEM_memory_map;
rc = HYPERVISOR_memory_op(op, &memmap);
if (rc == -ENOSYS) {
+ BUG_ON(xen_initial_domain());
memmap.nr_entries = 1;
map[0].addr = 0ULL;
map[0].size = mem_end;
@@ -201,12 +204,13 @@ char * __init xen_memory_setup(void)
}
/*
- * Even though this is normal, usable memory under Xen, reserve
- * ISA memory anyway because too many things think they can poke
+ * In domU, the ISA region is normal, usable memory, but we
+ * reserve ISA memory anyway because too many things poke
* about in there.
*
- * In a dom0 kernel, this region is identity mapped with the
- * hardware ISA area, so it really is out of bounds.
+ * In Dom0, the host E820 information can leave gaps in the
+ * ISA range, which would cause us to release those pages. To
+ * avoid this, we unconditionally reserve them here.
*/
e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS,
E820_RESERVED);