[Xen-changelog] [xen-unstable] libxc: fix incorrect scanning of pfn array in pagebuf during migration

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Shriram Rajagopalan <rshriram@xxxxxxxxx>
# Date 1299171327 0
# Node ID 5bc39222773de23c885237287902152dd53c1077
# Parent  9dfd7ffcd76c70191dcca9be0820483baa6cafa3
libxc: fix incorrect scanning of pfn array in pagebuf during migration

xc_domain_restore.c:apply_batch function makes two passes over the pfn_types
array in pagebuf to allocate the needed MFNs. The curbatch parameter to this
function specifies the array offset in pfn_types, from where the current scan
should begin. But this variable is not taken into account (index always starts
at 0) during the two passes. While this [bug] does not manifest itsef during
save/restore or live migration, under Remus, xc_domain_restore fails due to
corrupt guest page tables.

(This appears to have been broken by 21588:6c3d8aec202d which reverted
two changesets from before Remus support was added and hence
reintroduced some none-Remus compatible bits.)

Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---


diff -r 9dfd7ffcd76c -r 5bc39222773d tools/libxc/xc_domain_restore.c
--- a/tools/libxc/xc_domain_restore.c   Thu Mar 03 15:14:30 2011 +0000
+++ b/tools/libxc/xc_domain_restore.c   Thu Mar 03 16:55:27 2011 +0000
@@ -907,8 +907,8 @@
     for ( i = 0; i < j; i++ )
     {
         unsigned long pfn, pagetype;
-        pfn      = pagebuf->pfn_types[i] & ~XEN_DOMCTL_PFINFO_LTAB_MASK;
-        pagetype = pagebuf->pfn_types[i] &  XEN_DOMCTL_PFINFO_LTAB_MASK;
+        pfn      = pagebuf->pfn_types[i + curbatch] & 
~XEN_DOMCTL_PFINFO_LTAB_MASK;
+        pagetype = pagebuf->pfn_types[i + curbatch] &  
XEN_DOMCTL_PFINFO_LTAB_MASK;
 
         if ( (pagetype != XEN_DOMCTL_PFINFO_XTAB) && 
              (ctx->p2m[pfn] == INVALID_P2M_ENTRY) )
@@ -934,8 +934,8 @@
     for ( i = 0; i < j; i++ )
     {
         unsigned long pfn, pagetype;
-        pfn      = pagebuf->pfn_types[i] & ~XEN_DOMCTL_PFINFO_LTAB_MASK;
-        pagetype = pagebuf->pfn_types[i] &  XEN_DOMCTL_PFINFO_LTAB_MASK;
+        pfn      = pagebuf->pfn_types[i + curbatch] & 
~XEN_DOMCTL_PFINFO_LTAB_MASK;
+        pagetype = pagebuf->pfn_types[i + curbatch] &  
XEN_DOMCTL_PFINFO_LTAB_MASK;
 
         if ( pagetype == XEN_DOMCTL_PFINFO_XTAB )
             region_mfn[i] = ~0UL; /* map will fail but we don't care */

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