[Xen-changelog] [xen-unstable] [XEN] Extend fix from 12403:680b37789200 to other emulation paths.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
# Node ID a07d6a05792e5cfc8ca08a4db44e79ae1b5bee96
# Parent  bb76a76985febd022dd27c7456abccd12529aa7b
[XEN] Extend fix from 12403:680b37789200 to other emulation paths.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm/shadow/multi.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff -r bb76a76985fe -r a07d6a05792e xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c    Tue Nov 14 17:00:05 2006 +0000
+++ b/xen/arch/x86/mm/shadow/multi.c    Tue Nov 14 17:11:45 2006 +0000
@@ -3778,7 +3778,7 @@ sh_x86_emulate_write(struct vcpu *v, uns
         shadow_validate_guest_pt_write(v, mfn, addr, bytes_on_page);
         bytes -= bytes_on_page;
         /* If we are writing zeros to this page, might want to unshadow */
-        if ( *(u32 *)addr == 0 )
+        if ( likely(bytes_on_page >= 4) && (*(u32 *)addr == 0) )
             check_for_early_unshadow(v, mfn);
         sh_unmap_domain_page(addr);
     }
@@ -3823,7 +3823,7 @@ sh_x86_emulate_cmpxchg(struct vcpu *v, u
                   vaddr, prev, old, new, *(unsigned long *)addr, bytes);
 
     /* If we are writing zeros to this page, might want to unshadow */
-    if ( *(u8 *)addr == 0 )
+    if ( likely(bytes >= 4) && (*(u32 *)addr == 0) )
         check_for_early_unshadow(v, mfn);
 
     sh_unmap_domain_page(addr);
@@ -3858,7 +3858,7 @@ sh_x86_emulate_cmpxchg8b(struct vcpu *v,
         rv = X86EMUL_CMPXCHG_FAILED;
 
     /* If we are writing zeros to this page, might want to unshadow */
-    if ( *(u8 *)addr == 0 )
+    if ( *(u32 *)addr == 0 )
         check_for_early_unshadow(v, mfn);
 
     sh_unmap_domain_page(addr);

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