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pve-qemu-qoup/debian/patches/pve/0017-PVE-add-savevm-async-for-background-state-snapshots.patch
Fiona Ebner 10e1093325 update submodule and patches to QEMU 8.1.2 
Bigger notable changes:

* Commit 1a30b0f5d7 ("block: .bdrv_open is non-coroutine and
  unlocked") broke the PVE backup patches, in particular setting up
  the backup dump block driver, because bdrv_new_open_driver() cannot
  be called from a coroutine. To fix it, bdrv_co_open() is used
  instead, and while it's a much more involved function, the result
  should be essentially the same. The only difference I noticed is
  that the BDRV_O_ALLOW_RDWR flag is also set in the resulting bds
  (block driver state), but that shouldn't hurt.

Smaller notable changes:

* aio_set_fd_handler() dropped its 'is_external' parameter stating
  that all callers now pass false in 60f782b6b7 ("aio: remove
  aio_disable_external() API"). The calls in the PVE patches also
  passed false, so just drop the parameter too.

* global_state_store() does not have a return value anymore, so the
  user in the PVE savevm-async patch was adapted. For context, see
  c33f1829f8 ("migration: never fail in global_state_store()").

* Renames affecting the PVE savevm-async patch:
  migrate_use_block() -> migrate_block() and ram_counters -> mig_stats
  9d4b1e5f22 ("migration: Move migrate_use_block() to options.c")
  aff3f6606d ("migration: Rename ram_counters to mig_stats")

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
2023-10-24 15:01:23 +02:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Mon, 6 Apr 2020 12:16:46 +0200
Subject: [PATCH] PVE: add savevm-async for background state snapshots
Put qemu_savevm_state_{header,setup} into the main loop and the rest
of the iteration into a coroutine. The former need to lock the
iothread (and we can't unlock it in the coroutine), and the latter
can't deal with being in a separate thread, so a coroutine it must
be.
Truncate output file at 1024 boundary.
Do not block the VM and save the state on aborting a snapshot, as the
snapshot will be invalid anyway.
Also, when aborting, wait for the target file to be closed, otherwise a
client might run into race-conditions when trying to remove the file
still opened by QEMU.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
[SR: improve aborting
register yank before migration_incoming_state_destroy]
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
[FE: further improve aborting
adapt to removal of QEMUFileOps
improve condition for entering final stage
adapt to QAPI and other changes for 8.0]
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
hmp-commands-info.hx | 13 +
hmp-commands.hx | 17 ++
include/migration/snapshot.h | 2 +
include/monitor/hmp.h | 3 +
migration/meson.build | 1 +
migration/savevm-async.c | 531 +++++++++++++++++++++++++++++++++++
monitor/hmp-cmds.c | 38 +++
qapi/migration.json | 34 +++
qapi/misc.json | 16 ++
qemu-options.hx | 12 +
softmmu/vl.c | 10 +
11 files changed, 677 insertions(+)
create mode 100644 migration/savevm-async.c
diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
index f5b37eb74a..10fdd822e0 100644
--- a/hmp-commands-info.hx
+++ b/hmp-commands-info.hx
@@ -525,6 +525,19 @@ SRST
Show current migration parameters.
ERST
+ {
+ .name = "savevm",
+ .args_type = "",
+ .params = "",
+ .help = "show savevm status",
+ .cmd = hmp_info_savevm,
+ },
+
+SRST
+ ``info savevm``
+ Show savevm status.
+ERST
+
{
.name = "balloon",
.args_type = "",
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 2cbd0f77a0..e352f86872 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1865,3 +1865,20 @@ SRST
List event channels in the guest
ERST
#endif
+
+ {
+ .name = "savevm-start",
+ .args_type = "statefile:s?",
+ .params = "[statefile]",
+ .help = "Prepare for snapshot and halt VM. Save VM state to statefile.",
+ .cmd = hmp_savevm_start,
+ },
+
+ {
+ .name = "savevm-end",
+ .args_type = "",
+ .params = "",
+ .help = "Resume VM after snaphot.",
+ .cmd = hmp_savevm_end,
+ .coroutine = true,
+ },
diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index e72083b117..c846d37806 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -61,4 +61,6 @@ bool delete_snapshot(const char *name,
bool has_devices, strList *devices,
Error **errp);
+int load_snapshot_from_blockdev(const char *filename, Error **errp);
+
#endif
diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
index 13f9a2dedb..7a7def7530 100644
--- a/include/monitor/hmp.h
+++ b/include/monitor/hmp.h
@@ -28,6 +28,7 @@ void hmp_info_status(Monitor *mon, const QDict *qdict);
void hmp_info_uuid(Monitor *mon, const QDict *qdict);
void hmp_info_chardev(Monitor *mon, const QDict *qdict);
void hmp_info_mice(Monitor *mon, const QDict *qdict);
+void hmp_info_savevm(Monitor *mon, const QDict *qdict);
void hmp_info_migrate(Monitor *mon, const QDict *qdict);
void hmp_info_migrate_capabilities(Monitor *mon, const QDict *qdict);
void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict);
@@ -94,6 +95,8 @@ void hmp_closefd(Monitor *mon, const QDict *qdict);
void hmp_mouse_move(Monitor *mon, const QDict *qdict);
void hmp_mouse_button(Monitor *mon, const QDict *qdict);
void hmp_mouse_set(Monitor *mon, const QDict *qdict);
+void hmp_savevm_start(Monitor *mon, const QDict *qdict);
+void hmp_savevm_end(Monitor *mon, const QDict *qdict);
void hmp_sendkey(Monitor *mon, const QDict *qdict);
void coroutine_fn hmp_screendump(Monitor *mon, const QDict *qdict);
void hmp_chardev_add(Monitor *mon, const QDict *qdict);
diff --git a/migration/meson.build b/migration/meson.build
index 37ddcb5d60..07f6057acc 100644
--- a/migration/meson.build
+++ b/migration/meson.build
@@ -26,6 +26,7 @@ system_ss.add(files(
'options.c',
'postcopy-ram.c',
'savevm.c',
+ 'savevm-async.c',
'socket.c',
'tls.c',
'threadinfo.c',
diff --git a/migration/savevm-async.c b/migration/savevm-async.c
new file mode 100644
index 0000000000..e9fc18fb10
--- /dev/null
+++ b/migration/savevm-async.c
@@ -0,0 +1,531 @@
+#include "qemu/osdep.h"
+#include "migration/channel-savevm-async.h"
+#include "migration/migration.h"
+#include "migration/migration-stats.h"
+#include "migration/options.h"
+#include "migration/savevm.h"
+#include "migration/snapshot.h"
+#include "migration/global_state.h"
+#include "migration/ram.h"
+#include "migration/qemu-file.h"
+#include "sysemu/sysemu.h"
+#include "sysemu/runstate.h"
+#include "block/block.h"
+#include "sysemu/block-backend.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qerror.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qapi-commands-migration.h"
+#include "qapi/qapi-commands-misc.h"
+#include "qapi/qapi-commands-block.h"
+#include "qemu/cutils.h"
+#include "qemu/timer.h"
+#include "qemu/main-loop.h"
+#include "qemu/rcu.h"
+#include "qemu/yank.h"
+
+/* #define DEBUG_SAVEVM_STATE */
+
+#ifdef DEBUG_SAVEVM_STATE
+#define DPRINTF(fmt, ...) \
+ do { printf("savevm-async: " fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+ do { } while (0)
+#endif
+
+enum {
+ SAVE_STATE_DONE,
+ SAVE_STATE_ERROR,
+ SAVE_STATE_ACTIVE,
+ SAVE_STATE_COMPLETED,
+ SAVE_STATE_CANCELLED
+};
+
+
+static struct SnapshotState {
+ BlockBackend *target;
+ size_t bs_pos;
+ int state;
+ Error *error;
+ Error *blocker;
+ int saved_vm_running;
+ QEMUFile *file;
+ int64_t total_time;
+ QEMUBH *finalize_bh;
+ Coroutine *co;
+ QemuCoSleep target_close_wait;
+} snap_state;
+
+static bool savevm_aborted(void)
+{
+ return snap_state.state == SAVE_STATE_CANCELLED ||
+ snap_state.state == SAVE_STATE_ERROR;
+}
+
+SaveVMInfo *qmp_query_savevm(Error **errp)
+{
+ SaveVMInfo *info = g_malloc0(sizeof(*info));
+ struct SnapshotState *s = &snap_state;
+
+ if (s->state != SAVE_STATE_DONE) {
+ info->has_bytes = true;
+ info->bytes = s->bs_pos;
+ switch (s->state) {
+ case SAVE_STATE_ERROR:
+ info->status = g_strdup("failed");
+ info->has_total_time = true;
+ info->total_time = s->total_time;
+ if (s->error) {
+ info->error = g_strdup(error_get_pretty(s->error));
+ }
+ break;
+ case SAVE_STATE_ACTIVE:
+ info->status = g_strdup("active");
+ info->has_total_time = true;
+ info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
+ - s->total_time;
+ break;
+ case SAVE_STATE_COMPLETED:
+ info->status = g_strdup("completed");
+ info->has_total_time = true;
+ info->total_time = s->total_time;
+ break;
+ }
+ }
+
+ return info;
+}
+
+static int save_snapshot_cleanup(void)
+{
+ int ret = 0;
+
+ DPRINTF("save_snapshot_cleanup\n");
+
+ snap_state.total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) -
+ snap_state.total_time;
+
+ if (snap_state.file) {
+ ret = qemu_fclose(snap_state.file);
+ snap_state.file = NULL;
+ }
+
+ if (snap_state.target) {
+ if (!savevm_aborted()) {
+ /* try to truncate, but ignore errors (will fail on block devices).
+ * note1: bdrv_read() need whole blocks, so we need to round up
+ * note2: PVE requires 1024 (BDRV_SECTOR_SIZE*2) alignment
+ */
+ size_t size = QEMU_ALIGN_UP(snap_state.bs_pos, BDRV_SECTOR_SIZE*2);
+ blk_truncate(snap_state.target, size, false, PREALLOC_MODE_OFF, 0, NULL);
+ }
+ blk_op_unblock_all(snap_state.target, snap_state.blocker);
+ error_free(snap_state.blocker);
+ snap_state.blocker = NULL;
+ blk_unref(snap_state.target);
+ snap_state.target = NULL;
+
+ qemu_co_sleep_wake(&snap_state.target_close_wait);
+ }
+
+ return ret;
+}
+
+static void G_GNUC_PRINTF(1, 2) save_snapshot_error(const char *fmt, ...)
+{
+ va_list ap;
+ char *msg;
+
+ va_start(ap, fmt);
+ msg = g_strdup_vprintf(fmt, ap);
+ va_end(ap);
+
+ DPRINTF("save_snapshot_error: %s\n", msg);
+
+ if (!snap_state.error) {
+ error_set(&snap_state.error, ERROR_CLASS_GENERIC_ERROR, "%s", msg);
+ }
+
+ g_free (msg);
+
+ snap_state.state = SAVE_STATE_ERROR;
+}
+
+static void process_savevm_finalize(void *opaque)
+{
+ int ret;
+ AioContext *iohandler_ctx = iohandler_get_aio_context();
+ MigrationState *ms = migrate_get_current();
+
+ bool aborted = savevm_aborted();
+
+#ifdef DEBUG_SAVEVM_STATE
+ int64_t start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+#endif
+
+ qemu_bh_delete(snap_state.finalize_bh);
+ snap_state.finalize_bh = NULL;
+ snap_state.co = NULL;
+
+ /* We need to own the target bdrv's context for the following functions,
+ * so move it back. It can stay in the main context and live out its live
+ * there, since we're done with it after this method ends anyway.
+ */
+ aio_context_acquire(iohandler_ctx);
+ blk_set_aio_context(snap_state.target, qemu_get_aio_context(), NULL);
+ aio_context_release(iohandler_ctx);
+
+ ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
+ if (ret < 0) {
+ save_snapshot_error("vm_stop_force_state error %d", ret);
+ }
+
+ if (!aborted) {
+ /* skip state saving if we aborted, snapshot will be invalid anyway */
+ (void)qemu_savevm_state_complete_precopy(snap_state.file, false, false);
+ ret = qemu_file_get_error(snap_state.file);
+ if (ret < 0) {
+ save_snapshot_error("qemu_savevm_state_complete_precopy error %d", ret);
+ }
+ }
+
+ DPRINTF("state saving complete\n");
+ DPRINTF("timing: process_savevm_finalize (state saving) took %ld ms\n",
+ qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - start_time);
+
+ /* clear migration state */
+ migrate_set_state(&ms->state, MIGRATION_STATUS_SETUP,
+ ret || aborted ? MIGRATION_STATUS_FAILED : MIGRATION_STATUS_COMPLETED);
+ ms->to_dst_file = NULL;
+
+ qemu_savevm_state_cleanup();
+
+ ret = save_snapshot_cleanup();
+ if (ret < 0) {
+ save_snapshot_error("save_snapshot_cleanup error %d", ret);
+ } else if (snap_state.state == SAVE_STATE_ACTIVE) {
+ snap_state.state = SAVE_STATE_COMPLETED;
+ } else if (aborted) {
+ /*
+ * If there was an error, there's no need to set a new one here.
+ * If the snapshot was canceled, leave setting the state to
+ * qmp_savevm_end(), which is waked by save_snapshot_cleanup().
+ */
+ } else {
+ save_snapshot_error("process_savevm_cleanup: invalid state: %d",
+ snap_state.state);
+ }
+ if (snap_state.saved_vm_running) {
+ vm_start();
+ snap_state.saved_vm_running = false;
+ }
+
+ DPRINTF("timing: process_savevm_finalize (full) took %ld ms\n",
+ qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - start_time);
+}
+
+static void coroutine_fn process_savevm_co(void *opaque)
+{
+ int ret;
+ int64_t maxlen;
+ BdrvNextIterator it;
+ BlockDriverState *bs = NULL;
+
+#ifdef DEBUG_SAVEVM_STATE
+ int64_t start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+#endif
+
+ ret = qemu_file_get_error(snap_state.file);
+ if (ret < 0) {
+ save_snapshot_error("qemu_savevm_state_setup failed");
+ return;
+ }
+
+ while (snap_state.state == SAVE_STATE_ACTIVE) {
+ uint64_t pending_size, pend_precopy, pend_postcopy;
+ uint64_t threshold = 400 * 1000;
+
+ /*
+ * pending_{estimate,exact} are expected to be called without iothread
+ * lock. Similar to what is done in migration.c, call the exact variant
+ * only once pend_precopy in the estimate is below the threshold.
+ */
+ qemu_mutex_unlock_iothread();
+ qemu_savevm_state_pending_estimate(&pend_precopy, &pend_postcopy);
+ if (pend_precopy <= threshold) {
+ qemu_savevm_state_pending_exact(&pend_precopy, &pend_postcopy);
+ }
+ qemu_mutex_lock_iothread();
+ pending_size = pend_precopy + pend_postcopy;
+
+ /*
+ * A guest reaching this cutoff is dirtying lots of RAM. It should be
+ * large enough so that the guest can't dirty this much between the
+ * check and the guest actually being stopped, but it should be small
+ * enough to avoid long downtimes for non-hibernation snapshots.
+ */
+ maxlen = blk_getlength(snap_state.target) - 100*1024*1024;
+
+ /* Note that there is no progress for pend_postcopy when iterating */
+ if (pend_precopy > threshold && snap_state.bs_pos + pending_size < maxlen) {
+ ret = qemu_savevm_state_iterate(snap_state.file, false);
+ if (ret < 0) {
+ save_snapshot_error("qemu_savevm_state_iterate error %d", ret);
+ break;
+ }
+ DPRINTF("savevm iterate pending size %lu ret %d\n", pending_size, ret);
+ } else {
+ qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
+ global_state_store();
+
+ DPRINTF("savevm iterate complete\n");
+ break;
+ }
+ }
+
+ DPRINTF("timing: process_savevm_co took %ld ms\n",
+ qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - start_time);
+
+#ifdef DEBUG_SAVEVM_STATE
+ int64_t start_time_flush = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+#endif
+ /* If a drive runs in an IOThread we can flush it async, and only
+ * need to sync-flush whatever IO happens between now and
+ * vm_stop_force_state. bdrv_next can only be called from main AioContext,
+ * so move there now and after every flush.
+ */
+ aio_co_reschedule_self(qemu_get_aio_context());
+ for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+ /* target has BDRV_O_NO_FLUSH, no sense calling bdrv_flush on it */
+ if (bs == blk_bs(snap_state.target)) {
+ continue;
+ }
+
+ AioContext *bs_ctx = bdrv_get_aio_context(bs);
+ if (bs_ctx != qemu_get_aio_context()) {
+ DPRINTF("savevm: async flushing drive %s\n", bs->filename);
+ aio_co_reschedule_self(bs_ctx);
+ bdrv_graph_co_rdlock();
+ bdrv_flush(bs);
+ bdrv_graph_co_rdunlock();
+ aio_co_reschedule_self(qemu_get_aio_context());
+ }
+ }
+
+ DPRINTF("timing: async flushing took %ld ms\n",
+ qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - start_time_flush);
+
+ qemu_bh_schedule(snap_state.finalize_bh);
+}
+
+void qmp_savevm_start(const char *statefile, Error **errp)
+{
+ Error *local_err = NULL;
+ MigrationState *ms = migrate_get_current();
+ AioContext *iohandler_ctx = iohandler_get_aio_context();
+
+ int bdrv_oflags = BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_NO_FLUSH;
+
+ if (snap_state.state != SAVE_STATE_DONE) {
+ error_set(errp, ERROR_CLASS_GENERIC_ERROR,
+ "VM snapshot already started\n");
+ return;
+ }
+
+ if (migration_is_running(ms->state)) {
+ error_set(errp, ERROR_CLASS_GENERIC_ERROR, QERR_MIGRATION_ACTIVE);
+ return;
+ }
+
+ if (migrate_block()) {
+ error_set(errp, ERROR_CLASS_GENERIC_ERROR,
+ "Block migration and snapshots are incompatible");
+ return;
+ }
+
+ /* initialize snapshot info */
+ snap_state.saved_vm_running = runstate_is_running();
+ snap_state.bs_pos = 0;
+ snap_state.total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+ snap_state.blocker = NULL;
+ snap_state.target_close_wait = (QemuCoSleep){ .to_wake = NULL };
+
+ if (snap_state.error) {
+ error_free(snap_state.error);
+ snap_state.error = NULL;
+ }
+
+ if (!statefile) {
+ vm_stop(RUN_STATE_SAVE_VM);
+ snap_state.state = SAVE_STATE_COMPLETED;
+ return;
+ }
+
+ if (qemu_savevm_state_blocked(errp)) {
+ return;
+ }
+
+ /* Open the image */
+ QDict *options = NULL;
+ options = qdict_new();
+ qdict_put_str(options, "driver", "raw");
+ snap_state.target = blk_new_open(statefile, NULL, options, bdrv_oflags, &local_err);
+ if (!snap_state.target) {
+ error_set(errp, ERROR_CLASS_GENERIC_ERROR, "failed to open '%s'", statefile);
+ goto restart;
+ }
+
+ QIOChannel *ioc = QIO_CHANNEL(qio_channel_savevm_async_new(snap_state.target,
+ &snap_state.bs_pos));
+ snap_state.file = qemu_file_new_output(ioc);
+
+ if (!snap_state.file) {
+ error_set(errp, ERROR_CLASS_GENERIC_ERROR, "failed to open '%s'", statefile);
+ goto restart;
+ }
+
+ /*
+ * qemu_savevm_* paths use migration code and expect a migration state.
+ * State is cleared in process_savevm_co, but has to be initialized
+ * here (blocking main thread, from QMP) to avoid race conditions.
+ */
+ migrate_init(ms);
+ memset(&mig_stats, 0, sizeof(mig_stats));
+ memset(&compression_counters, 0, sizeof(compression_counters));
+ ms->to_dst_file = snap_state.file;
+
+ error_setg(&snap_state.blocker, "block device is in use by savevm");
+ blk_op_block_all(snap_state.target, snap_state.blocker);
+
+ snap_state.state = SAVE_STATE_ACTIVE;
+ snap_state.finalize_bh = qemu_bh_new(process_savevm_finalize, &snap_state);
+ snap_state.co = qemu_coroutine_create(&process_savevm_co, NULL);
+ qemu_mutex_unlock_iothread();
+ qemu_savevm_state_header(snap_state.file);
+ qemu_savevm_state_setup(snap_state.file);
+ qemu_mutex_lock_iothread();
+
+ /* Async processing from here on out happens in iohandler context, so let
+ * the target bdrv have its home there.
+ */
+ blk_set_aio_context(snap_state.target, iohandler_ctx, &local_err);
+
+ aio_co_schedule(iohandler_ctx, snap_state.co);
+
+ return;
+
+restart:
+
+ save_snapshot_error("setup failed");
+
+ if (snap_state.saved_vm_running) {
+ vm_start();
+ snap_state.saved_vm_running = false;
+ }
+}
+
+void coroutine_fn qmp_savevm_end(Error **errp)
+{
+ int64_t timeout;
+
+ if (snap_state.state == SAVE_STATE_DONE) {
+ error_set(errp, ERROR_CLASS_GENERIC_ERROR,
+ "VM snapshot not started\n");
+ return;
+ }
+
+ if (snap_state.state == SAVE_STATE_ACTIVE) {
+ snap_state.state = SAVE_STATE_CANCELLED;
+ goto wait_for_close;
+ }
+
+ if (snap_state.saved_vm_running) {
+ vm_start();
+ snap_state.saved_vm_running = false;
+ }
+
+ snap_state.state = SAVE_STATE_DONE;
+
+wait_for_close:
+ if (!snap_state.target) {
+ DPRINTF("savevm-end: no target file open\n");
+ return;
+ }
+
+ /* wait until cleanup is done before returning, this ensures that after this
+ * call exits the statefile will be closed and can be removed immediately */
+ DPRINTF("savevm-end: waiting for cleanup\n");
+ timeout = 30L * 1000 * 1000 * 1000;
+ qemu_co_sleep_ns_wakeable(&snap_state.target_close_wait,
+ QEMU_CLOCK_REALTIME, timeout);
+ if (snap_state.target) {
+ save_snapshot_error("timeout waiting for target file close in "
+ "qmp_savevm_end");
+ /* we cannot assume the snapshot finished in this case, so leave the
+ * state alone - caller has to figure something out */
+ return;
+ }
+
+ // File closed and no other error, so ensure next snapshot can be started.
+ if (snap_state.state != SAVE_STATE_ERROR) {
+ snap_state.state = SAVE_STATE_DONE;
+ }
+
+ DPRINTF("savevm-end: cleanup done\n");
+}
+
+int load_snapshot_from_blockdev(const char *filename, Error **errp)
+{
+ BlockBackend *be;
+ Error *local_err = NULL;
+ Error *blocker = NULL;
+
+ QEMUFile *f;
+ size_t bs_pos = 0;
+ int ret = -EINVAL;
+
+ be = blk_new_open(filename, NULL, NULL, 0, &local_err);
+
+ if (!be) {
+ error_setg(errp, "Could not open VM state file");
+ goto the_end;
+ }
+
+ error_setg(&blocker, "block device is in use by load state");
+ blk_op_block_all(be, blocker);
+
+ /* restore the VM state */
+ f = qemu_file_new_input(QIO_CHANNEL(qio_channel_savevm_async_new(be, &bs_pos)));
+ if (!f) {
+ error_setg(errp, "Could not open VM state file");
+ goto the_end;
+ }
+
+ qemu_system_reset(SHUTDOWN_CAUSE_NONE);
+ ret = qemu_loadvm_state(f);
+
+ /* dirty bitmap migration has a special case we need to trigger manually */
+ dirty_bitmap_mig_before_vm_start();
+
+ qemu_fclose(f);
+
+ /* state_destroy assumes a real migration which would have added a yank */
+ yank_register_instance(MIGRATION_YANK_INSTANCE, &error_abort);
+
+ migration_incoming_state_destroy();
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Error while loading VM state");
+ goto the_end;
+ }
+
+ ret = 0;
+
+ the_end:
+ if (be) {
+ blk_op_unblock_all(be, blocker);
+ error_free(blocker);
+ blk_unref(be);
+ }
+ return ret;
+}
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 6c559b48c8..91be698308 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -22,6 +22,7 @@
#include "monitor/monitor-internal.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-control.h"
+#include "qapi/qapi-commands-migration.h"
#include "qapi/qapi-commands-misc.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qerror.h"
@@ -443,3 +444,40 @@ void hmp_info_mtree(Monitor *mon, const QDict *qdict)
mtree_info(flatview, dispatch_tree, owner, disabled);
}
+
+void hmp_savevm_start(Monitor *mon, const QDict *qdict)
+{
+ Error *errp = NULL;
+ const char *statefile = qdict_get_try_str(qdict, "statefile");
+
+ qmp_savevm_start(statefile, &errp);
+ hmp_handle_error(mon, errp);
+}
+
+void coroutine_fn hmp_savevm_end(Monitor *mon, const QDict *qdict)
+{
+ Error *errp = NULL;
+
+ qmp_savevm_end(&errp);
+ hmp_handle_error(mon, errp);
+}
+
+void hmp_info_savevm(Monitor *mon, const QDict *qdict)
+{
+ SaveVMInfo *info;
+ info = qmp_query_savevm(NULL);
+
+ if (info->status) {
+ monitor_printf(mon, "savevm status: %s\n", info->status);
+ monitor_printf(mon, "total time: %" PRIu64 " milliseconds\n",
+ info->total_time);
+ } else {
+ monitor_printf(mon, "savevm status: not running\n");
+ }
+ if (info->has_bytes) {
+ monitor_printf(mon, "Bytes saved: %"PRIu64"\n", info->bytes);
+ }
+ if (info->error) {
+ monitor_printf(mon, "Error: %s\n", info->error);
+ }
+}
diff --git a/qapi/migration.json b/qapi/migration.json
index 8843e74b59..aca0ca1ac1 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -291,6 +291,40 @@
'*dirty-limit-throttle-time-per-round': 'uint64',
'*dirty-limit-ring-full-time': 'uint64'} }
+##
+# @SaveVMInfo:
+#
+# Information about current migration process.
+#
+# @status: string describing the current savevm status.
+# This can be 'active', 'completed', 'failed'.
+# If this field is not returned, no savevm process
+# has been initiated
+#
+# @error: string containing error message is status is failed.
+#
+# @total-time: total amount of milliseconds since savevm started.
+# If savevm has ended, it returns the total save time
+#
+# @bytes: total amount of data transfered
+#
+# Since: 1.3
+##
+{ 'struct': 'SaveVMInfo',
+ 'data': {'*status': 'str', '*error': 'str',
+ '*total-time': 'int', '*bytes': 'int'} }
+
+##
+# @query-savevm:
+#
+# Returns information about current savevm process.
+#
+# Returns: @SaveVMInfo
+#
+# Since: 1.3
+##
+{ 'command': 'query-savevm', 'returns': 'SaveVMInfo' }
+
##
# @query-migrate:
#
diff --git a/qapi/misc.json b/qapi/misc.json
index cda2effa81..94a58bb0bf 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -456,6 +456,22 @@
##
{ 'command': 'query-fdsets', 'returns': ['FdsetInfo'] }
+##
+# @savevm-start:
+#
+# Prepare for snapshot and halt VM. Save VM state to statefile.
+#
+##
+{ 'command': 'savevm-start', 'data': { '*statefile': 'str' } }
+
+##
+# @savevm-end:
+#
+# Resume VM after a snapshot.
+#
+##
+{ 'command': 'savevm-end', 'coroutine': true }
+
##
# @CommandLineParameterType:
#
diff --git a/qemu-options.hx b/qemu-options.hx
index b56f6b2fb2..c8c78c92d4 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4479,6 +4479,18 @@ SRST
Start right away with a saved state (``loadvm`` in monitor)
ERST
+DEF("loadstate", HAS_ARG, QEMU_OPTION_loadstate, \
+ "-loadstate file\n" \
+ " start right away with a saved state\n",
+ QEMU_ARCH_ALL)
+SRST
+``-loadstate file``
+ Start right away with a saved state. This option does not rollback
+ disk state like @code{loadvm}, so user must make sure that disk
+ have correct state. @var{file} can be any valid device URL. See the section
+ for "Device URL Syntax" for more information.
+ERST
+
#ifndef _WIN32
DEF("daemonize", 0, QEMU_OPTION_daemonize, \
"-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
diff --git a/softmmu/vl.c b/softmmu/vl.c
index b0b96f67fa..f3251de3e7 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -164,6 +164,7 @@ static const char *accelerators;
static bool have_custom_ram_size;
static const char *ram_memdev_id;
static QDict *machine_opts_dict;
+static const char *loadstate;
static QTAILQ_HEAD(, ObjectOption) object_opts = QTAILQ_HEAD_INITIALIZER(object_opts);
static QTAILQ_HEAD(, DeviceOption) device_opts = QTAILQ_HEAD_INITIALIZER(device_opts);
static int display_remote;
@@ -2643,6 +2644,12 @@ void qmp_x_exit_preconfig(Error **errp)
if (loadvm) {
load_snapshot(loadvm, NULL, false, NULL, &error_fatal);
+ } else if (loadstate) {
+ Error *local_err = NULL;
+ if (load_snapshot_from_blockdev(loadstate, &local_err) < 0) {
+ error_report_err(local_err);
+ autostart = 0;
+ }
}
if (replay_mode != REPLAY_MODE_NONE) {
replay_vmstate_init();
@@ -3190,6 +3197,9 @@ void qemu_init(int argc, char **argv)
case QEMU_OPTION_loadvm:
loadvm = optarg;
break;
+ case QEMU_OPTION_loadstate:
+ loadstate = optarg;
+ break;
case QEMU_OPTION_full_screen:
dpy.has_full_screen = true;
dpy.full_screen = true;
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