When doing migration using the fd: URI, QEMU will fetch the file
descriptor passed in via the monitor at
fd_start_outgoing|incoming_migration(), which means the checks at
migration_channels_and_transport_compatible() happen too soon and we
don't know at that point whether the FD refers to a plain file or a
socket.
For this reason, we've been allowing a migration channel of type
SOCKET_ADDRESS_TYPE_FD to pass the initial verifications in scenarios
where the socket migration is not supported, such as with fd + multifd.
The commit decdc76772 ("migration/multifd: Add mapped-ram support to
fd: URI") was supposed to add a second check prior to starting
migration to make sure a socket fd is not passed instead of a file fd,
but failed to do so.
Add the missing verification and update the comment explaining this
situation which is currently incorrect.
Fixes: decdc76772 ("migration/multifd: Add mapped-ram support to fd: URI")
Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
migration/fd.c | 8 ++++++++
migration/file.c | 7 +++++++
migration/migration.c | 6 +++---
3 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/migration/fd.c b/migration/fd.c
index 39a52e5c90..c07030f715 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -22,6 +22,7 @@
#include "migration.h"
#include "monitor/monitor.h"
#include "io/channel-file.h"
+#include "io/channel-socket.h"
#include "io/channel-util.h"
#include "options.h"
#include "trace.h"
@@ -95,6 +96,13 @@ void fd_start_incoming_migration(const char *fdname, Error
**errp)
}
if (migrate_multifd()) {
+ if (fd_is_socket(fd)) {
+ error_setg(errp,
+ "Multifd migration to a socket FD is not supported");
+ object_unref(ioc);
+ return;
+ }
+
file_create_incoming_channels(ioc, errp);
} else {
qio_channel_set_name(ioc, "migration-fd-incoming");
diff --git a/migration/file.c b/migration/file.c
index ddde0ca818..b6e8ba13f2 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -15,6 +15,7 @@
#include "file.h"
#include "migration.h"
#include "io/channel-file.h"
+#include "io/channel-socket.h"
#include "io/channel-util.h"
#include "options.h"
#include "trace.h"
@@ -58,6 +59,12 @@ bool file_send_channel_create(gpointer opaque, Error **errp)
int fd = fd_args_get_fd();
if (fd && fd != -1) {
+ if (fd_is_socket(fd)) {
+ error_setg(errp,
+ "Multifd migration to a socket FD is not supported");
+ goto out;
+ }
+
ioc = qio_channel_file_new_dupfd(fd, errp);
} else {
ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
diff --git a/migration/migration.c b/migration/migration.c
index 644e073b7d..f60bd371e3 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -166,9 +166,9 @@ static bool transport_supports_seeking(MigrationAddress
*addr)
}
/*
- * At this point, the user might not yet have passed the file
- * descriptor to QEMU, so we cannot know for sure whether it
- * refers to a plain file or a socket. Let it through anyway.
+ * At this point QEMU has not yet fetched the fd passed in by the
+ * user, so we cannot know for sure whether it refers to a plain
+ * file or a socket. Let it through anyway and check at fd.c.
*/
if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
return addr->u.socket.type == SOCKET_ADDRESS_TYPE_FD;
--
2.35.3
