[PATCH 2/2] migration/postcopy: map large zero page in postcopy_ram_incoming_setup()

[Wei Yang]

postcopy_ram_incoming_setup() and postcopy_ram_incoming_cleanup() are
counterpart. It is reasonable to map/unmap large zero page in these two
functions respectively.

Signed-off-by: Wei Yang <address@hidden>
---
 migration/postcopy-ram.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index e554f93eec..813cfa5c42 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1142,6 +1142,22 @@ int postcopy_ram_incoming_setup(MigrationIncomingState 
*mis)
         return -1;
     }
 
+    /*
+     * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
+     */
+    mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
+                                       PROT_READ | PROT_WRITE,
+                                       MAP_PRIVATE | MAP_ANONYMOUS,
+                                       -1, 0);
+    if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
+        int e = errno;
+        mis->postcopy_tmp_zero_page = NULL;
+        error_report("%s: Failed to map large zero page %s",
+                     __func__, strerror(e));
+        return -e;
+    }
+    memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
+
     /*
      * Ballooning can mark pages as absent while we're postcopying
      * that would cause false userfaults.
@@ -1248,23 +1264,7 @@ int postcopy_place_page_zero(MigrationIncomingState 
*mis, void *host,
                                            qemu_ram_block_host_offset(rb,
                                                                       host));
     } else {
-        /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
-        if (!mis->postcopy_tmp_zero_page) {
-            mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
-                                               PROT_READ | PROT_WRITE,
-                                               MAP_PRIVATE | MAP_ANONYMOUS,
-                                               -1, 0);
-            if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
-                int e = errno;
-                mis->postcopy_tmp_zero_page = NULL;
-                error_report("%s: %s mapping large zero page",
-                             __func__, strerror(e));
-                return -e;
-            }
-            memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
-        }
-        return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
-                                   rb);
+        return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
     }
 }
 
-- 
2.17.1