migration/postcopy: allocate tmp_page in setup stage

During migration, a tmp page is allocated so that we could place a whole
host page during postcopy.

Currently the page is allocated during load stage, this is a little bit
late. And more important, if we failed to allocate it, the error is not
checked properly. Even it is NULL, we would still use it.

This patch moves the allocation to setup stage and if failed error
message would be printed and caller would notice it.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 1f63e65ed7053ca9a0885d2aa891f89220caf195..9a16f52a791825fd8640e8e35747b3189b55ee74 100644 (file)
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1134,6 +1134,16 @@ int postcopy_ram_enable_notify(MigrationIncomingState *mis)
         return -1;
     }
 
+    mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
+                                  PROT_READ | PROT_WRITE, MAP_PRIVATE |
+                                  MAP_ANONYMOUS, -1, 0);
+    if (mis->postcopy_tmp_page == MAP_FAILED) {
+        mis->postcopy_tmp_page = NULL;
+        error_report("%s: Failed to map postcopy_tmp_page %s",
+                     __func__, strerror(errno));
+        return -1;
+    }
+
     /*
      * Ballooning can mark pages as absent while we're postcopying
      * that would cause false userfaults.
@@ -1260,30 +1270,6 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
     }
 }
 
-/*
- * Returns a target page of memory that can be mapped at a later point in time
- * using postcopy_place_page
- * The same address is used repeatedly, postcopy_place_page just takes the
- * backing page away.
- * Returns: Pointer to allocated page
- *
- */
-void *postcopy_get_tmp_page(MigrationIncomingState *mis)
-{
-    if (!mis->postcopy_tmp_page) {
-        mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
-                             PROT_READ | PROT_WRITE, MAP_PRIVATE |
-                             MAP_ANONYMOUS, -1, 0);
-        if (mis->postcopy_tmp_page == MAP_FAILED) {
-            mis->postcopy_tmp_page = NULL;
-            error_report("%s: %s", __func__, strerror(errno));
-            return NULL;
-        }
-    }
-
-    return mis->postcopy_tmp_page;
-}
-
 #else
 /* No target OS support, stubs just fail */
 void fill_destination_postcopy_migration_info(MigrationInfo *info)
@@ -1341,12 +1327,6 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
     return -1;
 }
 
-void *postcopy_get_tmp_page(MigrationIncomingState *mis)
-{
-    assert(0);
-    return NULL;
-}
-
 int postcopy_wake_shared(struct PostCopyFD *pcfd,
                          uint64_t client_addr,
                          RAMBlock *rb)

diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 9c8bd2bae07f4cc7be5d1b53a40d40afabdb91ea..fb4cd11d28744101ba7685ff472056d53c72e0bc 100644 (file)
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -100,13 +100,6 @@ typedef enum {
     POSTCOPY_INCOMING_END
 } PostcopyState;
 
-/*
- * Allocate a page of memory that can be mapped at a later point in time
- * using postcopy_place_page
- * Returns: Pointer to allocated page
- */
-void *postcopy_get_tmp_page(MigrationIncomingState *mis);
-
 PostcopyState postcopy_state_get(void);
 /* Set the state and return the old state */
 PostcopyState postcopy_state_set(PostcopyState new_state);

diff --git a/migration/ram.c b/migration/ram.c
index e29c8b34088be5f6306040af43d78babfecc36d5..071687ef37815b517d9ffec11037a725a295f161 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4032,7 +4032,7 @@ static int ram_load_postcopy(QEMUFile *f)
     bool matches_target_page_size = false;
     MigrationIncomingState *mis = migration_incoming_get_current();
     /* Temporary page that is later 'placed' */
-    void *postcopy_host_page = postcopy_get_tmp_page(mis);
+    void *postcopy_host_page = mis->postcopy_tmp_page;
     void *last_host = NULL;
     bool all_zero = false;