[Qemu-devel] [PATCH 7/7 V8] migration/ram: ensure write persistence on loading all data to PMEM.

[junyan . he]

From: Junyan He <address@hidden>

Because we need to make sure the pmem kind memory data is synced
after migration, we choose to call pmem_persist() when the migration
finish. This will make sure the data of pmem is safe and will not
lose if power is off.

Signed-off-by: Junyan He <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
Reviewed-by: Igor Mammedov <address@hidden>
---
 include/qemu/pmem.h |  1 +
 migration/ram.c     | 10 +++++++++-
 stubs/pmem.c        |  4 ++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/qemu/pmem.h b/include/qemu/pmem.h
index 00d6680..8f52b08 100644
--- a/include/qemu/pmem.h
+++ b/include/qemu/pmem.h
@@ -17,6 +17,7 @@
 #else  /* !CONFIG_LIBPMEM */
 
 void *pmem_memcpy_persist(void *pmemdest, const void *src, size_t len);
+void pmem_persist(const void *addr, size_t len);
 
 #endif /* CONFIG_LIBPMEM */
 
diff --git a/migration/ram.c b/migration/ram.c
index 9c03e2b..62dfe75 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -33,6 +33,7 @@
 #include "qemu/bitops.h"
 #include "qemu/bitmap.h"
 #include "qemu/main-loop.h"
+#include "qemu/pmem.h"
 #include "xbzrle.h"
 #include "ram.h"
 #include "migration.h"
@@ -3541,6 +3542,13 @@ static int ram_load_setup(QEMUFile *f, void *opaque)
 static int ram_load_cleanup(void *opaque)
 {
     RAMBlock *rb;
+
+    RAMBLOCK_FOREACH_MIGRATABLE(rb) {
+        if (ramblock_is_pmem(rb)) {
+            pmem_persist(rb->host, rb->used_length);
+        }
+    }
+
     xbzrle_load_cleanup();
     compress_threads_load_cleanup();
 
@@ -3896,7 +3904,7 @@ static int ram_load(QEMUFile *f, void *opaque, int 
version_id)
 static bool ram_has_postcopy(void *opaque)
 {
     RAMBlock *rb;
-    RAMBLOCK_FOREACH(rb) {
+    RAMBLOCK_FOREACH_MIGRATABLE(rb) {
         if (ramblock_is_pmem(rb)) {
             info_report("Block: %s, host: %p is a nvdimm memory, postcopy"
                          "is not supported now!", rb->idstr, rb->host);
diff --git a/stubs/pmem.c b/stubs/pmem.c
index b4ec72d..f794262 100644
--- a/stubs/pmem.c
+++ b/stubs/pmem.c
@@ -17,3 +17,7 @@ void *pmem_memcpy_persist(void *pmemdest, const void *src, 
size_t len)
 {
     return memcpy(pmemdest, src, len);
 }
+
+void pmem_persist(const void *addr, size_t len)
+{
+}
-- 
2.7.4