migration/multifd: Support incoming mapped-ram stream format

For the incoming mapped-ram migration we need to read the ramblock
headers, get the pages bitmap and send the host address of each
non-zero page to the multifd channel thread for writing.

Usage on HMP is:

(qemu) migrate_set_capability multifd on
(qemu) migrate_set_capability mapped-ram on
(qemu) migrate_incoming file:migfile

(the ram.h include needs to move because we've been previously relying
on it being included from migration.c. Now file.h will start including
multifd.h before migration.o is processed)

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-22-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

1 files changed, 28 insertions, 3 deletions

diff --git a/migration/multifd.c b/migration/multifd.c
index 8118145428..419feb7df1 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -18,7 +18,6 @@
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "file.h"
-#include "ram.h"
 #include "migration.h"
 #include "migration-stats.h"
 #include "socket.h"
@@ -251,7 +250,7 @@ static int nocomp_recv(MultiFDRecvParams *p, Error **errp)
     uint32_t flags;
 
     if (!multifd_use_packets()) {
-        return 0;
+        return multifd_file_recv_data(p, errp);
     }
 
     flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
@@ -1331,22 +1330,48 @@ void multifd_recv_cleanup(void)
 void multifd_recv_sync_main(void)
 {
     int thread_count = migrate_multifd_channels();
+    bool file_based = !multifd_use_packets();
     int i;
 
-    if (!migrate_multifd() || !multifd_use_packets()) {
+    if (!migrate_multifd()) {
         return;
     }
 
     /*
+     * File-based channels don't use packets and therefore need to
+     * wait for more work. Release them to start the sync.
+     */
+    if (file_based) {
+        for (i = 0; i < thread_count; i++) {
+            MultiFDRecvParams *p = &multifd_recv_state->params[i];
+
+            trace_multifd_recv_sync_main_signal(p->id);
+            qemu_sem_post(&p->sem);
+        }
+    }
+
+    /*
      * Initiate the synchronization by waiting for all channels.
+     *
      * For socket-based migration this means each channel has received
      * the SYNC packet on the stream.
+     *
+     * For file-based migration this means each channel is done with
+     * the work (pending_job=false).
      */
     for (i = 0; i < thread_count; i++) {
         trace_multifd_recv_sync_main_wait(i);
         qemu_sem_wait(&multifd_recv_state->sem_sync);
     }
 
+    if (file_based) {
+        /*
+         * For file-based loading is done in one iteration. We're
+         * done.
+         */
+        return;
+    }
+
     /*
      * Sync done. Release the channels for the next iteration.
      */