Migration pull for 9.0-rc1

- Fabiano's patch to revert fd: support on mapped-ram
 - Peter's fix on postcopy regression on unnecessary dirty syncs
 - Fabiano's fix on mapped-ram rare corrupt on zero page handling
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Merge tag 'migration-20240322-pull-request' of https://gitlab.com/peterx/qemu into staging

Migration pull for 9.0-rc1

- Fabiano's patch to revert fd: support on mapped-ram
- Peter's fix on postcopy regression on unnecessary dirty syncs
- Fabiano's fix on mapped-ram rare corrupt on zero page handling

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# gpg: Signature made Fri 22 Mar 2024 16:13:23 GMT
# gpg:                using EDDSA key B9184DC20CC457DACF7DD1A93B5FCCCDF3ABD706
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# gpg: Good signature from "Peter Xu <xzpeter@gmail.com>" [marginal]
# gpg:                 aka "Peter Xu <peterx@redhat.com>" [marginal]
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# Primary key fingerprint: B918 4DC2 0CC4 57DA CF7D  D1A9 3B5F CCCD F3AB D706

* tag 'migration-20240322-pull-request' of https://gitlab.com/peterx/qemu:
  migration/multifd: Fix clearing of mapped-ram zero pages
  migration/postcopy: Fix high frequency sync
  migration: Revert mapped-ram multifd support to fd: URI

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

migration/fd.c

@@ -15,42 +15,19 @@
  */
 
 #include "qemu/osdep.h"
-#include "qapi/error.h"
 #include "channel.h"
 #include "fd.h"
 #include "file.h"
 #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"
 
 
-static struct FdOutgoingArgs {
-    int fd;
-} outgoing_args;
-
-int fd_args_get_fd(void)
-{
-    return outgoing_args.fd;
-}
-
-void fd_cleanup_outgoing_migration(void)
-{
-    if (outgoing_args.fd > 0) {
-        close(outgoing_args.fd);
-        outgoing_args.fd = -1;
-    }
-}
-
 void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
 {
     QIOChannel *ioc;
     int fd = monitor_get_fd(monitor_cur(), fdname, errp);
-    int newfd;
-
     if (fd == -1) {
         return;
     }
@@ -62,18 +39,6 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
         return;
     }
 
-    /*
-     * This is dup()ed just to avoid referencing an fd that might
-     * be already closed by the iochannel.
-     */
-    newfd = dup(fd);
-    if (newfd == -1) {
-        error_setg_errno(errp, errno, "Could not dup FD %d", fd);
-        object_unref(ioc);
-        return;
-    }
-    outgoing_args.fd = newfd;
-
     qio_channel_set_name(ioc, "migration-fd-outgoing");
     migration_channel_connect(s, ioc, NULL, NULL);
     object_unref(OBJECT(ioc));
@@ -104,20 +69,9 @@ void fd_start_incoming_migration(const char *fdname, Error **errp)
         return;
     }
 
-    if (migrate_multifd()) {
+    qio_channel_set_name(ioc, "migration-fd-incoming");
-        if (fd_is_socket(fd)) {
+    qio_channel_add_watch_full(ioc, G_IO_IN,
-            error_setg(errp,
+                               fd_accept_incoming_migration,
-                       "Multifd migration to a socket FD is not supported");
+                               NULL, NULL,
-            object_unref(ioc);
+                               g_main_context_get_thread_default());
-            return;
-        }
-
-        file_create_incoming_channels(ioc, errp);
-    } else {
-        qio_channel_set_name(ioc, "migration-fd-incoming");
-        qio_channel_add_watch_full(ioc, G_IO_IN,
-                                   fd_accept_incoming_migration,
-                                   NULL, NULL,
-                                   g_main_context_get_thread_default());
-    }
 }

migration/fd.h

@@ -20,6 +20,4 @@ void fd_start_incoming_migration(const char *fdname, Error **errp);
 
 void fd_start_outgoing_migration(MigrationState *s, const char *fdname,
                                  Error **errp);
-void fd_cleanup_outgoing_migration(void);
-int fd_args_get_fd(void);
 #endif

migration/file.c

@@ -11,7 +11,6 @@
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "channel.h"
-#include "fd.h"
 #include "file.h"
 #include "migration.h"
 #include "io/channel-file.h"
@@ -55,27 +54,15 @@ bool file_send_channel_create(gpointer opaque, Error **errp)
 {
     QIOChannelFile *ioc;
     int flags = O_WRONLY;
-    bool ret = false;
+    bool ret = true;
-    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);
-    }
 
+    ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
     if (!ioc) {
+        ret = false;
         goto out;
     }
 
     multifd_channel_connect(opaque, QIO_CHANNEL(ioc));
-    ret = true;
 
 out:
     /*

migration/migration.c

@@ -140,10 +140,6 @@ static bool transport_supports_multi_channels(MigrationAddress *addr)
     if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
         SocketAddress *saddr = &addr->u.socket;
 
-        if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            return migrate_mapped_ram();
-        }
-
         return (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
                 saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
                 saddr->type == SOCKET_ADDRESS_TYPE_VSOCK);
@@ -165,15 +161,6 @@ static bool transport_supports_seeking(MigrationAddress *addr)
         return true;
     }
 
-    /*
-     * 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;
-    }
-
     return false;
 }
 
@@ -3212,17 +3199,16 @@ typedef enum {
  */
 static MigIterateState migration_iteration_run(MigrationState *s)
 {
-    uint64_t must_precopy, can_postcopy;
+    uint64_t must_precopy, can_postcopy, pending_size;
     Error *local_err = NULL;
     bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
     bool can_switchover = migration_can_switchover(s);
 
     qemu_savevm_state_pending_estimate(&must_precopy, &can_postcopy);
-    uint64_t pending_size = must_precopy + can_postcopy;
+    pending_size = must_precopy + can_postcopy;
-
     trace_migrate_pending_estimate(pending_size, must_precopy, can_postcopy);
 
-    if (must_precopy <= s->threshold_size) {
+    if (pending_size < s->threshold_size) {
         qemu_savevm_state_pending_exact(&must_precopy, &can_postcopy);
         pending_size = must_precopy + can_postcopy;
         trace_migrate_pending_exact(pending_size, must_precopy, can_postcopy);

migration/multifd.c

@@ -18,7 +18,6 @@
 #include "exec/ramblock.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
-#include "fd.h"
 #include "file.h"
 #include "migration.h"
 #include "migration-stats.h"
@@ -112,7 +111,6 @@ void multifd_send_channel_created(void)
 static void multifd_set_file_bitmap(MultiFDSendParams *p)
 {
     MultiFDPages_t *pages = p->pages;
-    uint32_t zero_num = p->pages->num - p->pages->normal_num;
 
     assert(pages->block);
 
@@ -120,7 +118,7 @@ static void multifd_set_file_bitmap(MultiFDSendParams *p)
         ramblock_set_file_bmap_atomic(pages->block, pages->offset[i], true);
     }
 
-    for (int i = p->pages->num; i < zero_num; i++) {
+    for (int i = p->pages->normal_num; i < p->pages->num; i++) {
         ramblock_set_file_bmap_atomic(pages->block, pages->offset[i], false);
     }
 }
@@ -794,7 +792,6 @@ static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp)
 static void multifd_send_cleanup_state(void)
 {
     file_cleanup_outgoing_migration();
-    fd_cleanup_outgoing_migration();
     socket_cleanup_outgoing_migration();
     qemu_sem_destroy(&multifd_send_state->channels_created);
     qemu_sem_destroy(&multifd_send_state->channels_ready);

tests/qtest/migration-test.c

@@ -2536,13 +2536,6 @@ static void *migrate_precopy_fd_file_start(QTestState *from, QTestState *to)
     return NULL;
 }
 
-static void *migrate_fd_file_mapped_ram_start(QTestState *from, QTestState *to)
-{
-    migrate_mapped_ram_start(from, to);
-
-    return migrate_precopy_fd_file_start(from, to);
-}
-
 static void test_migrate_precopy_fd_file(void)
 {
     MigrateCommon args = {
@@ -2553,36 +2546,6 @@ static void test_migrate_precopy_fd_file(void)
     };
     test_file_common(&args, true);
 }
-
-static void test_migrate_precopy_fd_file_mapped_ram(void)
-{
-    MigrateCommon args = {
-        .listen_uri = "defer",
-        .connect_uri = "fd:fd-mig",
-        .start_hook = migrate_fd_file_mapped_ram_start,
-        .finish_hook = test_migrate_fd_finish_hook
-    };
-    test_file_common(&args, true);
-}
-
-static void *migrate_multifd_fd_mapped_ram_start(QTestState *from,
-                                                QTestState *to)
-{
-    migrate_multifd_mapped_ram_start(from, to);
-    return migrate_precopy_fd_file_start(from, to);
-}
-
-static void test_multifd_fd_mapped_ram(void)
-{
-    MigrateCommon args = {
-        .connect_uri = "fd:fd-mig",
-        .listen_uri = "defer",
-        .start_hook = migrate_multifd_fd_mapped_ram_start,
-        .finish_hook = test_migrate_fd_finish_hook
-    };
-
-    test_file_common(&args, true);
-}
 #endif /* _WIN32 */
 
 static void do_test_validate_uuid(MigrateStart *args, bool should_fail)
@@ -3687,10 +3650,6 @@ int main(int argc, char **argv)
                        test_multifd_file_mapped_ram);
     migration_test_add("/migration/multifd/file/mapped-ram/live",
                        test_multifd_file_mapped_ram_live);
-#ifndef _WIN32
-    migration_test_add("/migration/multifd/fd/mapped-ram",
-                       test_multifd_fd_mapped_ram);
-#endif
 
 #ifdef CONFIG_GNUTLS
     migration_test_add("/migration/precopy/unix/tls/psk",
@@ -3753,8 +3712,6 @@ int main(int argc, char **argv)
                        test_migrate_precopy_fd_socket);
     migration_test_add("/migration/precopy/fd/file",
                        test_migrate_precopy_fd_file);
-    migration_test_add("/migration/precopy/fd/file/mapped-ram",
-                       test_migrate_precopy_fd_file_mapped_ram);
 #endif
     migration_test_add("/migration/validate_uuid", test_validate_uuid);
     migration_test_add("/migration/validate_uuid_error",