[xen staging] tools/migration: unify type checking for data pfns in the VM

[patchbot@xxxxxxx]

commit 5588ebcfca774477cf823949e5703b0ac48818cc
Author:     Olaf Hering <olaf@xxxxxxxxx>
AuthorDate: Thu Jul 1 11:56:07 2021 +0200
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Jul 6 10:49:58 2021 +0100

    tools/migration: unify type checking for data pfns in the VM
    
    Introduce a helper which decides if a given pfn in the migration
    stream is backed by memory.
    
    This highlights more clearly that type XEN_DOMCTL_PFINFO_XALLOC (a
    synthetic toolstack-only type used between Xen 4.2 to 4.5 which
    indicated a dirty page on the sending side for which no data will be
    send in the initial iteration) does get populated in the VM.
    
    No change in behaviour intended, except for invalid page types which now
    have a safer default.
    
    Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/libs/guest/xg_sr_common.h  | 29 +++++++++++++++++++++++++++++
 tools/libs/guest/xg_sr_restore.c |  4 +---
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/tools/libs/guest/xg_sr_common.h b/tools/libs/guest/xg_sr_common.h
index e8436d1abb..7f4b0439f6 100644
--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -484,6 +484,35 @@ static inline bool is_known_page_type(uint32_t type)
     }
 }
 
+/* Page type backed by RAM in the guest? */
+static inline bool page_type_to_populate(uint32_t type)
+{
+    switch ( type )
+    {
+    case XEN_DOMCTL_PFINFO_NOTAB:
+
+    case XEN_DOMCTL_PFINFO_L1TAB:
+    case XEN_DOMCTL_PFINFO_L1TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+    case XEN_DOMCTL_PFINFO_L2TAB:
+    case XEN_DOMCTL_PFINFO_L2TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+    case XEN_DOMCTL_PFINFO_L3TAB:
+    case XEN_DOMCTL_PFINFO_L3TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+    case XEN_DOMCTL_PFINFO_L4TAB:
+    case XEN_DOMCTL_PFINFO_L4TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+    case XEN_DOMCTL_PFINFO_XALLOC:
+        return true;
+
+    case XEN_DOMCTL_PFINFO_XTAB:
+    case XEN_DOMCTL_PFINFO_BROKEN:
+    default:
+        return false;
+    }
+}
+
 #endif
 /*
  * Local variables:
diff --git a/tools/libs/guest/xg_sr_restore.c b/tools/libs/guest/xg_sr_restore.c
index 508953fd3c..3d63442d45 100644
--- a/tools/libs/guest/xg_sr_restore.c
+++ b/tools/libs/guest/xg_sr_restore.c
@@ -152,9 +152,7 @@ int populate_pfns(struct xc_sr_context *ctx, unsigned int 
count,
 
     for ( i = 0; i < count; ++i )
     {
-        if ( (!types || (types &&
-                         (types[i] != XEN_DOMCTL_PFINFO_XTAB &&
-                          types[i] != XEN_DOMCTL_PFINFO_BROKEN))) &&
+        if ( (!types || page_type_to_populate(types[i])) &&
              !pfn_is_populated(ctx, original_pfns[i]) )
         {
             rc = pfn_set_populated(ctx, original_pfns[i]);
--
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