Merge remote-tracking branch 'remotes/juanquintela/tags/pull-migration-pull-request' into staging

Migration pull request

# gpg: Signature made Wed 29 Jan 2020 10:57:23 GMT
# gpg:                using RSA key 1899FF8EDEBF58CCEE034B82F487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>" [full]
# gpg:                 aka "Juan Quintela <quintela@trasno.org>" [full]
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* remotes/juanquintela/tags/pull-migration-pull-request:
  migration/compress: compress QEMUFile is not writable
  migration: Simplify get_qlist
  multifd: Split multifd code into its own file
  multifd: Make multifd_load_setup() get an Error parameter
  multifd: Make multifd_save_setup() get an Error parameter
  migration: Make checkpatch happy with comments
  multifd: Use qemu_target_page_size()
  multifd: multifd_send_sync_main only needs the qemufile
  multifd: multifd_queue_page only needs the qemufile
  multifd: multifd_send_pages only needs the qemufile
  ram_addr: Split RAMBlock definition
  migration/multifd: fix nullptr access in multifd_send_terminate_threads
  migration: Create migration_is_running()
  migration-test: Make sure that multifd and cancel works
  migration: Don't send data if we have stopped
  qemu-file: Don't do IO after shutdown
  multifd: Make sure that we don't do any IO after an error
  migration-test: Use g_free() instead of free()
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

MAINTAINERS

@@ -1975,6 +1975,7 @@ F: ioport.c
 F: include/exec/memop.h
 F: include/exec/memory.h
 F: include/exec/ram_addr.h
+F: include/exec/ramblock.h
 F: memory.c
 F: include/exec/memory-internal.h
 F: exec.c

include/exec/ram_addr.h

@@ -24,45 +24,7 @@
 #include "hw/xen/xen.h"
 #include "sysemu/tcg.h"
 #include "exec/ramlist.h"
-
-struct RAMBlock {
-    struct rcu_head rcu;
-    struct MemoryRegion *mr;
-    uint8_t *host;
-    uint8_t *colo_cache; /* For colo, VM's ram cache */
-    ram_addr_t offset;
-    ram_addr_t used_length;
-    ram_addr_t max_length;
-    void (*resized)(const char*, uint64_t length, void *host);
-    uint32_t flags;
-    /* Protected by iothread lock.  */
-    char idstr[256];
-    /* RCU-enabled, writes protected by the ramlist lock */
-    QLIST_ENTRY(RAMBlock) next;
-    QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
-    int fd;
-    size_t page_size;
-    /* dirty bitmap used during migration */
-    unsigned long *bmap;
-    /* bitmap of already received pages in postcopy */
-    unsigned long *receivedmap;
-
-    /*
-     * bitmap to track already cleared dirty bitmap.  When the bit is
-     * set, it means the corresponding memory chunk needs a log-clear.
-     * Set this up to non-NULL to enable the capability to postpone
-     * and split clearing of dirty bitmap on the remote node (e.g.,
-     * KVM).  The bitmap will be set only when doing global sync.
-     *
-     * NOTE: this bitmap is different comparing to the other bitmaps
-     * in that one bit can represent multiple guest pages (which is
-     * decided by the `clear_bmap_shift' variable below).  On
-     * destination side, this should always be NULL, and the variable
-     * `clear_bmap_shift' is meaningless.
-     */
-    unsigned long *clear_bmap;
-    uint8_t clear_bmap_shift;
-};
+#include "exec/ramblock.h"
 
 /**
  * clear_bmap_size: calculate clear bitmap size

include/exec/ramblock.h

+/*
+ * Declarations for cpu physical memory functions
+ *
+ * Copyright 2011 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ *  Avi Kivity <avi@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ *
+ */
+
+/*
+ * This header is for use by exec.c and memory.c ONLY.  Do not include it.
+ * The functions declared here will be removed soon.
+ */
+
+#ifndef QEMU_EXEC_RAMBLOCK_H
+#define QEMU_EXEC_RAMBLOCK_H
+
+#ifndef CONFIG_USER_ONLY
+#include "cpu-common.h"
+
+struct RAMBlock {
+    struct rcu_head rcu;
+    struct MemoryRegion *mr;
+    uint8_t *host;
+    uint8_t *colo_cache; /* For colo, VM's ram cache */
+    ram_addr_t offset;
+    ram_addr_t used_length;
+    ram_addr_t max_length;
+    void (*resized)(const char*, uint64_t length, void *host);
+    uint32_t flags;
+    /* Protected by iothread lock.  */
+    char idstr[256];
+    /* RCU-enabled, writes protected by the ramlist lock */
+    QLIST_ENTRY(RAMBlock) next;
+    QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
+    int fd;
+    size_t page_size;
+    /* dirty bitmap used during migration */
+    unsigned long *bmap;
+    /* bitmap of already received pages in postcopy */
+    unsigned long *receivedmap;
+
+    /*
+     * bitmap to track already cleared dirty bitmap.  When the bit is
+     * set, it means the corresponding memory chunk needs a log-clear.
+     * Set this up to non-NULL to enable the capability to postpone
+     * and split clearing of dirty bitmap on the remote node (e.g.,
+     * KVM).  The bitmap will be set only when doing global sync.
+     *
+     * NOTE: this bitmap is different comparing to the other bitmaps
+     * in that one bit can represent multiple guest pages (which is
+     * decided by the `clear_bmap_shift' variable below).  On
+     * destination side, this should always be NULL, and the variable
+     * `clear_bmap_shift' is meaningless.
+     */
+    unsigned long *clear_bmap;
+    uint8_t clear_bmap_shift;
+};
+#endif
+#endif

include/qemu/queue.h

@@ -515,6 +515,12 @@ union {                                                                 \
              (elm);                                                            \
              (elm) = *QLIST_RAW_NEXT(elm, entry))
 
+#define QLIST_RAW_INSERT_AFTER(head, prev, elem, entry) do {                   \
+        *QLIST_RAW_NEXT(prev, entry) = elem;                                   \
+        *QLIST_RAW_PREVIOUS(elem, entry) = QLIST_RAW_NEXT(prev, entry);        \
+        *QLIST_RAW_NEXT(elem, entry) = NULL;                                   \
+} while (0)
+
 #define QLIST_RAW_INSERT_HEAD(head, elm, entry) do {                           \
         void *first = *QLIST_RAW_FIRST(head);                                  \
         *QLIST_RAW_FIRST(head) = elm;                                          \
@@ -527,17 +533,4 @@ union {                                                                 \
         }                                                                      \
 } while (0)
 
-#define QLIST_RAW_REVERSE(head, elm, entry) do {                               \
-        void *iter = *QLIST_RAW_FIRST(head), *prev = NULL, *next;              \
-        while (iter) {                                                         \
-            next = *QLIST_RAW_NEXT(iter, entry);                               \
-            *QLIST_RAW_PREVIOUS(iter, entry) = QLIST_RAW_NEXT(next, entry);    \
-            *QLIST_RAW_NEXT(iter, entry) = prev;                               \
-            prev = iter;                                                       \
-            iter = next;                                                       \
-        }                                                                      \
-        *QLIST_RAW_FIRST(head) = prev;                                         \
-        *QLIST_RAW_PREVIOUS(prev, entry) = QLIST_RAW_FIRST(head);              \
-} while (0)
-
 #endif /* QEMU_SYS_QUEUE_H */

migration/Makefile.objs

@@ -7,6 +7,7 @@ common-obj-y += qemu-file-channel.o
 common-obj-y += xbzrle.o postcopy-ram.o
 common-obj-y += qjson.o
 common-obj-y += block-dirty-bitmap.o
+common-obj-y += multifd.o
 
 common-obj-$(CONFIG_RDMA) += rdma.o
 

migration/migration.c

@@ -53,6 +53,7 @@
 #include "monitor/monitor.h"
 #include "net/announce.h"
 #include "qemu/queue.h"
+#include "multifd.h"
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration transfer speed throttling */
 
@@ -518,13 +519,23 @@ fail:
     exit(EXIT_FAILURE);
 }
 
-static void migration_incoming_setup(QEMUFile *f)
+/**
+ * @migration_incoming_setup: Setup incoming migration
+ *
+ * Returns 0 for no error or 1 for error
+ *
+ * @f: file for main migration channel
+ * @errp: where to put errors
+ */
+static int migration_incoming_setup(QEMUFile *f, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
+    Error *local_err = NULL;
 
-    if (multifd_load_setup() != 0) {
+    if (multifd_load_setup(&local_err) != 0) {
         /* We haven't been able to create multifd threads
            nothing better to do */
+        error_report_err(local_err);
         exit(EXIT_FAILURE);
     }
 
@@ -532,6 +543,7 @@ static void migration_incoming_setup(QEMUFile *f)
         mis->from_src_file = f;
     }
     qemu_file_set_blocking(f, false);
+    return 0;
 }
 
 void migration_incoming_process(void)
@@ -572,19 +584,27 @@ static bool postcopy_try_recover(QEMUFile *f)
     return false;
 }
 
-void migration_fd_process_incoming(QEMUFile *f)
+void migration_fd_process_incoming(QEMUFile *f, Error **errp)
 {
+    Error *local_err = NULL;
+
     if (postcopy_try_recover(f)) {
         return;
     }
 
-    migration_incoming_setup(f);
+    if (migration_incoming_setup(f, &local_err)) {
+        if (local_err) {
+            error_propagate(errp, local_err);
+        }
+        return;
+    }
     migration_incoming_process();
 }
 
 void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
+    Error *local_err = NULL;
     bool start_migration;
 
     if (!mis->from_src_file) {
@@ -596,7 +616,12 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
             return;
         }
 
-        migration_incoming_setup(f);
+        if (migration_incoming_setup(f, &local_err)) {
+            if (local_err) {
+                error_propagate(errp, local_err);
+            }
+            return;
+        }
 
         /*
          * Common migration only needs one channel, so we can start
@@ -604,7 +629,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
          */
         start_migration = !migrate_use_multifd();
     } else {
-        Error *local_err = NULL;
         /* Multiple connections */
         assert(migrate_use_multifd());
         start_migration = multifd_recv_new_channel(ioc, &local_err);
@@ -829,6 +853,27 @@ bool migration_is_setup_or_active(int state)
     }
 }
 
+bool migration_is_running(int state)
+{
+    switch (state) {
+    case MIGRATION_STATUS_ACTIVE:
+    case MIGRATION_STATUS_POSTCOPY_ACTIVE:
+    case MIGRATION_STATUS_POSTCOPY_PAUSED:
+    case MIGRATION_STATUS_POSTCOPY_RECOVER:
+    case MIGRATION_STATUS_SETUP:
+    case MIGRATION_STATUS_PRE_SWITCHOVER:
+    case MIGRATION_STATUS_DEVICE:
+    case MIGRATION_STATUS_WAIT_UNPLUG:
+    case MIGRATION_STATUS_CANCELLING:
+    case MIGRATION_STATUS_COLO:
+        return true;
+
+    default:
+        return false;
+
+    }
+}
+
 static void populate_time_info(MigrationInfo *info, MigrationState *s)
 {
     info->has_status = true;
@@ -1077,7 +1122,7 @@ void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     MigrationCapabilityStatusList *cap;
     bool cap_list[MIGRATION_CAPABILITY__MAX];
 
-    if (migration_is_setup_or_active(s->state)) {
+    if (migration_is_running(s->state)) {
         error_setg(errp, QERR_MIGRATION_ACTIVE);
         return;
     }
@@ -1590,7 +1635,7 @@ static void migrate_fd_cancel(MigrationState *s)
 
     do {
         old_state = s->state;
-        if (!migration_is_setup_or_active(old_state)) {
+        if (!migration_is_running(old_state)) {
             break;
         }
         /* If the migration is paused, kick it out of the pause */
@@ -1888,9 +1933,7 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc,
         return true;
     }
 
-    if (migration_is_setup_or_active(s->state) ||
-        s->state == MIGRATION_STATUS_CANCELLING ||
-        s->state == MIGRATION_STATUS_COLO) {
+    if (migration_is_running(s->state)) {
         error_setg(errp, QERR_MIGRATION_ACTIVE);
         return false;
     }
@@ -3348,6 +3391,7 @@ static void *migration_thread(void *opaque)
 
 void migrate_fd_connect(MigrationState *s, Error *error_in)
 {
+    Error *local_err = NULL;
     int64_t rate_limit;
     bool resume = s->state == MIGRATION_STATUS_POSTCOPY_PAUSED;
 
@@ -3396,7 +3440,8 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
         return;
     }
 
-    if (multifd_save_setup() != 0) {
+    if (multifd_save_setup(&local_err) != 0) {
+        error_report_err(local_err);
         migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
                           MIGRATION_STATUS_FAILED);
         migrate_fd_cleanup(s);

migration/migration.h

@@ -265,7 +265,7 @@ struct MigrationState
 
 void migrate_set_state(int *state, int old_state, int new_state);
 
-void migration_fd_process_incoming(QEMUFile *f);
+void migration_fd_process_incoming(QEMUFile *f, Error **errp);
 void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
 void migration_incoming_process(void);
 
@@ -279,6 +279,7 @@ void migrate_fd_error(MigrationState *s, const Error *error);
 void migrate_fd_connect(MigrationState *s, Error *error_in);
 
 bool migration_is_setup_or_active(int state);
+bool migration_is_running(int state);
 
 void migrate_init(MigrationState *s);
 bool migration_is_blocked(Error **errp);

migration/multifd.h

+/*
+ * Multifd common functions
+ *
+ * Copyright (c) 2019-2020 Red Hat Inc
+ *
+ * Authors:
+ *  Juan Quintela <quintela@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_MIGRATION_MULTIFD_H
+#define QEMU_MIGRATION_MULTIFD_H
+
+int multifd_save_setup(Error **errp);
+void multifd_save_cleanup(void);
+int multifd_load_setup(Error **errp);
+int multifd_load_cleanup(Error **errp);
+bool multifd_recv_all_channels_created(void);
+bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
+void multifd_recv_sync_main(void);
+void multifd_send_sync_main(QEMUFile *f);
+int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset);
+
+#define MULTIFD_FLAG_SYNC (1 << 0)
+
+/* This value needs to be a multiple of qemu_target_page_size() */
+#define MULTIFD_PACKET_SIZE (512 * 1024)
+
+typedef struct {
+    uint32_t magic;
+    uint32_t version;
+    uint32_t flags;
+    /* maximum number of allocated pages */
+    uint32_t pages_alloc;
+    uint32_t pages_used;
+    /* size of the next packet that contains pages */
+    uint32_t next_packet_size;
+    uint64_t packet_num;
+    uint64_t unused[4];    /* Reserved for future use */
+    char ramblock[256];
+    uint64_t offset[];
+} __attribute__((packed)) MultiFDPacket_t;
+
+typedef struct {
+    /* number of used pages */
+    uint32_t used;
+    /* number of allocated pages */
+    uint32_t allocated;
+    /* global number of generated multifd packets */
+    uint64_t packet_num;
+    /* offset of each page */
+    ram_addr_t *offset;
+    /* pointer to each page */
+    struct iovec *iov;
+    RAMBlock *block;
+} MultiFDPages_t;
+
+typedef struct {
+    /* this fields are not changed once the thread is created */
+    /* channel number */
+    uint8_t id;
+    /* channel thread name */
+    char *name;
+    /* channel thread id */
+    QemuThread thread;
+    /* communication channel */
+    QIOChannel *c;
+    /* sem where to wait for more work */
+    QemuSemaphore sem;
+    /* this mutex protects the following parameters */
+    QemuMutex mutex;
+    /* is this channel thread running */
+    bool running;
+    /* should this thread finish */
+    bool quit;
+    /* thread has work to do */
+    int pending_job;
+    /* array of pages to sent */
+    MultiFDPages_t *pages;
+    /* packet allocated len */
+    uint32_t packet_len;
+    /* pointer to the packet */
+    MultiFDPacket_t *packet;
+    /* multifd flags for each packet */
+    uint32_t flags;
+    /* size of the next packet that contains pages */
+    uint32_t next_packet_size;
+    /* global number of generated multifd packets */
+    uint64_t packet_num;
+    /* thread local variables */
+    /* packets sent through this channel */
+    uint64_t num_packets;
+    /* pages sent through this channel */
+    uint64_t num_pages;
+    /* syncs main thread and channels */
+    QemuSemaphore sem_sync;
+}  MultiFDSendParams;
+
+typedef struct {
+    /* this fields are not changed once the thread is created */
+    /* channel number */
+    uint8_t id;
+    /* channel thread name */
+    char *name;
+    /* channel thread id */
+    QemuThread thread;
+    /* communication channel */
+    QIOChannel *c;
+    /* this mutex protects the following parameters */
+    QemuMutex mutex;
+    /* is this channel thread running */
+    bool running;
+    /* should this thread finish */
+    bool quit;
+    /* array of pages to receive */
+    MultiFDPages_t *pages;
+    /* packet allocated len */
+    uint32_t packet_len;
+    /* pointer to the packet */
+    MultiFDPacket_t *packet;
+    /* multifd flags for each packet */
+    uint32_t flags;
+    /* global number of generated multifd packets */
+    uint64_t packet_num;
+    /* thread local variables */
+    /* size of the next packet that contains pages */
+    uint32_t next_packet_size;
+    /* packets sent through this channel */
+    uint64_t num_packets;
+    /* pages sent through this channel */
+    uint64_t num_pages;
+    /* syncs main thread and channels */
+    QemuSemaphore sem_sync;
+} MultiFDRecvParams;
+
+#endif
+

migration/qemu-file.c

@@ -53,6 +53,8 @@ struct QEMUFile {
 
     int last_error;
     Error *last_error_obj;
+    /* has the file has been shutdown */
+    bool shutdown;
 };
 
 /*
@@ -61,10 +63,18 @@ struct QEMUFile {
  */
 int qemu_file_shutdown(QEMUFile *f)
 {
+    int ret;
+
+    f->shutdown = true;
     if (!f->ops->shut_down) {
         return -ENOSYS;
     }
-    return f->ops->shut_down(f->opaque, true, true, NULL);
+    ret = f->ops->shut_down(f->opaque, true, true, NULL);
+
+    if (!f->last_error) {
+        qemu_file_set_error(f, -EIO);
+    }
+    return ret;
 }
 
 /*
@@ -214,6 +224,9 @@ void qemu_fflush(QEMUFile *f)
         return;
     }
 
+    if (f->shutdown) {
+        return;
+    }
     if (f->iovcnt > 0) {
         expect = iov_size(f->iov, f->iovcnt);
         ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos,
@@ -328,6 +341,10 @@ static ssize_t qemu_fill_buffer(QEMUFile *f)
     f->buf_index = 0;
     f->buf_size = pending;
 
+    if (f->shutdown) {
+        return 0;
+    }
+
     len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
                              IO_BUF_SIZE - pending, &local_error);
     if (len > 0) {
@@ -642,6 +659,9 @@ int64_t qemu_ftell(QEMUFile *f)
 
 int qemu_file_rate_limit(QEMUFile *f)
 {
+    if (f->shutdown) {
+        return 1;
+    }
     if (qemu_file_get_error(f)) {
         return 1;
     }
@@ -744,11 +764,8 @@ static int qemu_compress_data(z_stream *stream, uint8_t *dest, size_t dest_len,
 /* Compress size bytes of data start at p and store the compressed
  * data to the buffer of f.
  *
- * When f is not writable, return -1 if f has no space to save the
- * compressed data.
- * When f is wirtable and it has no space to save the compressed data,
- * do fflush first, if f still has no space to save the compressed
- * data, return -1.
+ * Since the file is dummy file with empty_ops, return -1 if f has no space to
+ * save the compressed data.
  */
 ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
                                   const uint8_t *p, size_t size)
@@ -756,14 +773,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
     ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
 
     if (blen < compressBound(size)) {
-        if (!qemu_file_is_writable(f)) {
-            return -1;
-        }
-        qemu_fflush(f);
-        blen = IO_BUF_SIZE - sizeof(int32_t);
-        if (blen < compressBound(size)) {
-            return -1;
-        }
+        return -1;
     }
 
     blen = qemu_compress_data(stream, f->buf + f->buf_index + sizeof(int32_t),

migration/ram.h

@@ -41,13 +41,6 @@ int xbzrle_cache_resize(int64_t new_size, Error **errp);
 uint64_t ram_bytes_remaining(void);
 uint64_t ram_bytes_total(void);
 
-int multifd_save_setup(void);
-void multifd_save_cleanup(void);
-int multifd_load_setup(void);
-int multifd_load_cleanup(Error **errp);
-bool multifd_recv_all_channels_created(void);
-bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
-
 uint64_t ram_pagesize_summary(void);
 int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len);
 void acct_update_position(QEMUFile *f, size_t size, bool zero);

migration/rdma.c

@@ -4004,7 +4004,7 @@ static void rdma_accept_incoming_migration(void *opaque)
     }
 
     rdma->migration_started_on_destination = 1;
-    migration_fd_process_incoming(f);
+    migration_fd_process_incoming(f, errp);
 }
 
 void rdma_start_incoming_migration(const char *host_port, Error **errp)

migration/savevm.c

@@ -1531,9 +1531,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
     MigrationState *ms = migrate_get_current();
     MigrationStatus status;
 
-    if (migration_is_setup_or_active(ms->state) ||
-        ms->state == MIGRATION_STATUS_CANCELLING ||
-        ms->state == MIGRATION_STATUS_COLO) {
+    if (migration_is_running(ms->state)) {
         error_setg(errp, QERR_MIGRATION_ACTIVE);
         return -EINVAL;
     }

migration/vmstate-types.c

@@ -879,7 +879,7 @@ static int get_qlist(QEMUFile *f, void *pv, size_t unused_size,
     /* offset of the QLIST entry in a QLIST element */
     size_t entry_offset = field->start;
     int version_id = field->version_id;
-    void *elm;
+    void *elm, *prev = NULL;
 
     trace_get_qlist(field->name, vmsd->name, vmsd->version_id);
     if (version_id > vmsd->version_id) {
@@ -900,9 +900,13 @@ static int get_qlist(QEMUFile *f, void *pv, size_t unused_size,
             g_free(elm);
             return ret;
         }
-        QLIST_RAW_INSERT_HEAD(pv, elm, entry_offset);
+        if (!prev) {
+            QLIST_RAW_INSERT_HEAD(pv, elm, entry_offset);
+        } else {
+            QLIST_RAW_INSERT_AFTER(pv, prev, elm, entry_offset);
+        }
+        prev = elm;
     }
-    QLIST_RAW_REVERSE(pv, elm, entry_offset);
     trace_get_qlist_end(field->name, vmsd->name);
 
     return ret;

tests/qtest/migration-test.c

@@ -424,6 +424,14 @@ static void migrate_recover(QTestState *who, const char *uri)
     qobject_unref(rsp);
 }
 
+static void migrate_cancel(QTestState *who)
+{
+    QDict *rsp;
+
+    rsp = wait_command(who, "{ 'execute': 'migrate_cancel' }");
+    qobject_unref(rsp);
+}
+
 static void migrate_set_capability(QTestState *who, const char *capability,
                                    bool value)
 {
@@ -456,6 +464,8 @@ static void migrate_postcopy_start(QTestState *from, QTestState *to)
 typedef struct {
     bool hide_stderr;
     bool use_shmem;
+    /* only launch the target process */
+    bool only_target;
     char *opts_source;
     char *opts_target;
 } MigrateStart;
@@ -571,7 +581,9 @@ static int test_migrate_start(QTestState **from, QTestState **to,
                                  arch_source, shmem_opts, args->opts_source,
                                  ignore_stderr);
     g_free(arch_source);
-    *from = qtest_init(cmd_source);
+    if (!args->only_target) {
+        *from = qtest_init(cmd_source);
+    }
     g_free(cmd_source);
 
     cmd_target = g_strdup_printf("-accel kvm -accel tcg%s%s "
@@ -1291,7 +1303,104 @@ static void test_multifd_tcp(void)
     wait_for_serial("dest_serial");
     wait_for_migration_complete(from);
     test_migrate_end(from, to, true);
-    free(uri);
+    g_free(uri);
+}
+
+/*
+ * This test does:
+ *  source               target
+ *                       migrate_incoming
+ *     migrate
+ *     migrate_cancel
+ *                       launch another target
+ *     migrate
+ *
+ *  And see that it works
+ */
+
+static void test_multifd_tcp_cancel(void)
+{
+    MigrateStart *args = migrate_start_new();
+    QTestState *from, *to, *to2;
+    QDict *rsp;
+    char *uri;
+
+    args->hide_stderr = true;
+
+    if (test_migrate_start(&from, &to, "defer", args)) {
+        return;
+    }
+
+    /*
+     * We want to pick a speed slow enough that the test completes
+     * quickly, but that it doesn't complete precopy even on a slow
+     * machine, so also set the downtime.
+     */
+    /* 1 ms should make it not converge*/
+    migrate_set_parameter_int(from, "downtime-limit", 1);
+    /* 300MB/s */
+    migrate_set_parameter_int(from, "max-bandwidth", 30000000);
+
+    migrate_set_parameter_int(from, "multifd-channels", 16);
+    migrate_set_parameter_int(to, "multifd-channels", 16);
+
+    migrate_set_capability(from, "multifd", "true");
+    migrate_set_capability(to, "multifd", "true");
+
+    /* Start incoming migration from the 1st socket */
+    rsp = wait_command(to, "{ 'execute': 'migrate-incoming',"
+                           "  'arguments': { 'uri': 'tcp:127.0.0.1:0' }}");
+    qobject_unref(rsp);
+
+    /* Wait for the first serial output from the source */
+    wait_for_serial("src_serial");
+
+    uri = migrate_get_socket_address(to, "socket-address");
+
+    migrate_qmp(from, uri, "{}");
+
+    wait_for_migration_pass(from);
+
+    migrate_cancel(from);
+
+    args = migrate_start_new();
+    args->only_target = true;
+
+    if (test_migrate_start(&from, &to2, "defer", args)) {
+        return;
+    }
+
+    migrate_set_parameter_int(to2, "multifd-channels", 16);
+
+    migrate_set_capability(to2, "multifd", "true");
+
+    /* Start incoming migration from the 1st socket */
+    rsp = wait_command(to2, "{ 'execute': 'migrate-incoming',"
+                            "  'arguments': { 'uri': 'tcp:127.0.0.1:0' }}");
+    qobject_unref(rsp);
+
+    uri = migrate_get_socket_address(to2, "socket-address");
+
+    wait_for_migration_status(from, "cancelled", NULL);
+
+    /* 300ms it should converge */
+    migrate_set_parameter_int(from, "downtime-limit", 300);
+    /* 1GB/s */
+    migrate_set_parameter_int(from, "max-bandwidth", 1000000000);
+
+    migrate_qmp(from, uri, "{}");
+
+    wait_for_migration_pass(from);
+
+    if (!got_stop) {
+        qtest_qmp_eventwait(from, "STOP");
+    }
+    qtest_qmp_eventwait(to2, "RESUME");
+
+    wait_for_serial("dest_serial");
+    wait_for_migration_complete(from);
+    test_migrate_end(from, to2, true);
+    g_free(uri);
 }
 
 int main(int argc, char **argv)
@@ -1359,6 +1468,7 @@ int main(int argc, char **argv)
 
     qtest_add_func("/migration/auto_converge", test_migrate_auto_converge);
     qtest_add_func("/migration/multifd/tcp", test_multifd_tcp);
+    qtest_add_func("/migration/multifd/tcp/cancel", test_multifd_tcp_cancel);
 
     ret = g_test_run();