> From: Paolo Bonzini [mailto:pbonz...@redhat.com]
> On 04/05/2017 10:42, Pavel Dovgalyuk wrote:
> > From: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
> >
> > This patch does not allows saving/loading vmstate when
> > replay events queue is not empty. There is no reliable
> > way to save events queue, because it describes internal
> > coroutine state. Therefore saving and loading operations
> > should be deferred to another record/replay step.
>
> Can it actually be non-empty after bdrv_drain_all?
drain/flush cannot succeed, because started requests are
prisoned in the replay events queue.
> > Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
> > ---
> > include/sysemu/replay.h | 3 +++
> > migration/savevm.c | 13 +++++++++++++
> > replay/replay-snapshot.c | 6 ++++++
> > 3 files changed, 22 insertions(+)
> >
> > diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
> > index f1c0712795..5c9db2a2ef 100644
> > --- a/include/sysemu/replay.h
> > +++ b/include/sysemu/replay.h
> > @@ -164,5 +164,8 @@ void replay_audio_in(int *recorded, void *samples, int
> > *wpos, int size);
> > /*! Called at the start of execution.
> > Loads or saves initial vmstate depending on execution mode. */
> > void replay_vmstate_init(void);
> > +/*! Called to ensure that replay state is consistent and VM snapshot
> > + can be created */
> > +bool replay_can_snapshot(void);
> >
> > #endif
> > diff --git a/migration/savevm.c b/migration/savevm.c
> > index 03ae1bdeb4..358d22170d 100644
> > --- a/migration/savevm.c
> > +++ b/migration/savevm.c
> > @@ -54,6 +54,7 @@
> > #include "qemu/cutils.h"
> > #include "io/channel-buffer.h"
> > #include "io/channel-file.h"
> > +#include "sysemu/replay.h"
> >
> > #ifndef ETH_P_RARP
> > #define ETH_P_RARP 0x8035
> > @@ -2083,6 +2084,12 @@ int save_vmstate(Monitor *mon, const char *name)
> > Error *local_err = NULL;
> > AioContext *aio_context;
> >
> > + if (!replay_can_snapshot()) {
> > + monitor_printf(mon, "Record/replay does not allow making snapshot
> > right now. "
> > + "Try stopping at another step.\n");
> > + return ret;
> > + }
> > +
> > if (!bdrv_all_can_snapshot(&bs)) {
> > monitor_printf(mon, "Device '%s' is writable but does not "
> > "support snapshots.\n", bdrv_get_device_name(bs));
> > @@ -2244,6 +2251,12 @@ int load_vmstate(const char *name)
> > AioContext *aio_context;
> > MigrationIncomingState *mis = migration_incoming_get_current();
> >
> > + if (!replay_can_snapshot()) {
> > + error_report("Record/replay does not allow loading snapshot right
> > now. "
> > + "Try stopping at another step.\n");
> > + return -EINVAL;
> > + }
> > +
> > if (!bdrv_all_can_snapshot(&bs)) {
> > error_report("Device '%s' is writable but does not support
> > snapshots.",
> > bdrv_get_device_name(bs));
> > diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
> > index 65e2d375c2..438d82ec33 100644
> > --- a/replay/replay-snapshot.c
> > +++ b/replay/replay-snapshot.c
> > @@ -76,3 +76,9 @@ void replay_vmstate_init(void)
> > }
> > }
> > }
> > +
> > +bool replay_can_snapshot(void)
> > +{
> > + return replay_mode == REPLAY_MODE_NONE
> > + || !replay_has_events();
> > +}
> >
Pavel Dovgalyuk
