[PATCH 4/5] tools/migration: unify type checking for data pfns in the VM

[Andrew Cooper <andrew.cooper3@citrix.com>]

From: Olaf Hering <olaf@aepfle.de>

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@aepfle.de>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
 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 e8436d1abb14..7f4b0439f6bd 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 508953fd3cf7..3d63442d4537 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]);
-- 
2.11.0