migration/multifd: Add incoming QIOChannelFile support

On the receiving side we don't need to differentiate between main
channel and threads, so whichever channel is defined first gets to be
the main one. And since there are no packets, use the atomic channel
count to index into the params array.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-19-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

3 files changed, 30 insertions, 11 deletions

diff --git a/migration/file.c b/migration/file.c
index a350dd61f0..2f8b626b27 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -8,6 +8,7 @@
 #include "qemu/osdep.h"
 #include "exec/ramblock.h"
 #include "qemu/cutils.h"
+#include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "channel.h"
 #include "file.h"
@@ -15,6 +16,7 @@
 #include "multifd.h"
 #include "io/channel-file.h"
 #include "io/channel-util.h"
+#include "options.h"
 #include "trace.h"
 
 #define OFFSET_OPTION ",offset="
@@ -112,7 +114,8 @@ void file_start_incoming_migration(FileMigrationArgs *file_args, Error **errp)
     g_autofree char *filename = g_strdup(file_args->filename);
     QIOChannelFile *fioc = NULL;
     uint64_t offset = file_args->offset;
-    QIOChannel *ioc;
+    int channels = 1;
+    int i = 0;
 
     trace_migration_file_incoming(filename);
 
@@ -121,13 +124,29 @@ void file_start_incoming_migration(FileMigrationArgs *file_args, Error **errp)
         return;
     }
 
-    ioc = QIO_CHANNEL(fioc);
-    if (offset && qio_channel_io_seek(ioc, offset, SEEK_SET, errp) < 0) {
+    if (offset &&
+        qio_channel_io_seek(QIO_CHANNEL(fioc), offset, SEEK_SET, errp) < 0) {
         return;
     }
-    qio_channel_set_name(QIO_CHANNEL(ioc), "migration-file-incoming");
-    qio_channel_add_watch_full(ioc, G_IO_IN,
-                               file_accept_incoming_migration,
-                               NULL, NULL,
-                               g_main_context_get_thread_default());
+
+    if (migrate_multifd()) {
+        channels += migrate_multifd_channels();
+    }
+
+    do {
+        QIOChannel *ioc = QIO_CHANNEL(fioc);
+
+        qio_channel_set_name(ioc, "migration-file-incoming");
+        qio_channel_add_watch_full(ioc, G_IO_IN,
+                                   file_accept_incoming_migration,
+                                   NULL, NULL,
+                                   g_main_context_get_thread_default());
+
+        fioc = qio_channel_file_new_fd(dup(fioc->fd));
+
+        if (!fioc || fioc->fd == -1) {
+            error_setg(errp, "Error creating migration incoming channel");
+            break;
+        }
+    } while (++i < channels);
 }
diff --git a/migration/migration.c b/migration/migration.c
index 2669600d25..faeb75a59b 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -910,7 +910,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
     uint32_t channel_magic = 0;
     int ret = 0;
 
-    if (migrate_multifd() && !migrate_postcopy_ram() &&
+    if (migrate_multifd() && !migrate_mapped_ram() &&
+        !migrate_postcopy_ram() &&
         qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
         /*
          * With multiple channels, it is possible that we receive channels
diff --git a/migration/multifd.c b/migration/multifd.c
index caef1076ca..ea08f1aa9e 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -1545,8 +1545,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
         }
         trace_multifd_recv_new_channel(id);
     } else {
-        /* next patch gives this a meaningful value */
-        id = 0;
+        id = qatomic_read(&multifd_recv_state->count);
     }
 
     p = &multifd_recv_state->params[id];