[Xen-changelog] [xen-unstable] x86/mm: fix mod_l1_entry() return value when encountering r/o MMIO page

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1340271059 -7200
# Node ID baa85434d0ec16629ca30b7c07deaa9beb3ea9c5
# Parent  d4cdcf4d541cc4ce72c48df2e26c2b506c5b04bd
x86/mm: fix mod_l1_entry() return value when encountering r/o MMIO page

While putting together the workaround announced in
http://lists.xen.org/archives/html/xen-devel/2012-06/msg00709.html, I
found that mod_l1_entry(), upon encountering a set bit in
mmio_ro_ranges, would return 1 instead of 0 (the removal of the write
permission is supposed to be entirely transparent to the caller, even
more so to the calling guest).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
---


diff -r d4cdcf4d541c -r baa85434d0ec xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Thu Jun 21 11:30:22 2012 +0200
+++ b/xen/arch/x86/mm.c Thu Jun 21 11:30:59 2012 +0200
@@ -1875,6 +1875,7 @@ static int mod_l1_entry(l1_pgentry_t *pl
             break;
         case 1:
             l1e_remove_flags(nl1e, _PAGE_RW);
+            rc = 0;
             break;
         }
         if ( page )

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