[Xen-changelog] [xen-4.1-testing] x86-64: Fix memory hotplug epfn upper limit test for updating the compat M2P table

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Malcolm Crossley <malcolm.crossley@xxxxxxxxxx>
# Date 1335878038 -3600
# Node ID b1e2ca715ae7f60ecb4bac84dcab48d9bb3006d9
# Parent  99517f769cc861094d35bd9e681d78a5a2573265
x86-64: Fix memory hotplug epfn upper limit test for updating the compat M2P 
table

The epfn is being compared to (RDWR_COMPAT_MPT_VIRT_END -
RDWR_COMPAT_MPT_VIRT_START) without a 2 bit shift, resulting in the
epfn being compared to the size of the RDWR_COMPAT_MPT table in bytes
instead of the maximum page frame number that the RDWR_COMPAT_MPT
table can map.

Signed-off-by: Malcolm Crossley <malcolm.crossley@xxxxxxxxxx>
Committed-by: Jan Beulich <jbeulich@xxxxxxxx>
xen-unstable changeset:   25242:b7ce6a88bebb
xen-unstable date:        Wed Apr 25 12:35:56 2012 +0200
---


diff -r 99517f769cc8 -r b1e2ca715ae7 xen/arch/x86/x86_64/mm.c
--- a/xen/arch/x86/x86_64/mm.c  Tue Apr 24 18:38:19 2012 +0100
+++ b/xen/arch/x86/x86_64/mm.c  Tue May 01 14:13:58 2012 +0100
@@ -450,7 +450,7 @@ static int setup_compat_m2p_table(struct
     if   ((smap > ((RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) >> 
2)) )
         return 0;
 
-    if (epfn > (RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START))
+    if ( epfn > ((RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) >> 2) 
)
         epfn = (RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) >> 2;
 
     emap = ( (epfn + ((1UL << (L2_PAGETABLE_SHIFT - 2)) - 1 )) &

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