Re: [Qemu-devel] [PATCH v7 4/5] shutdown: Preserve shutdown cause through replay

From: "Pavel Dovgalyuk" <dovgaluk@ispras.ru>
To: 'Eric Blake' <eblake@redhat.com>, qemu-devel@nongnu.org
Cc: armbru@redhat.com, berrange@redhat.com,
	alistair.francis@xilinx.com,
	'Pavel Dovgalyuk' <pavel.dovgaluk@ispras.ru>,
	'Paolo Bonzini' <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v7 4/5] shutdown: Preserve shutdown cause through replay
Date: Wed, 10 May 2017 13:04:13 +0300	[thread overview]
Message-ID: <004801d2c974$c6e0db60$54a29220$@ru> (raw)
In-Reply-To: <20170508211953.28017-5-eblake@redhat.com>


> -----Original Message-----
> From: Eric Blake [mailto:eblake@redhat.com]
> Sent: Tuesday, May 09, 2017 12:20 AM
> To: qemu-devel@nongnu.org
> Cc: armbru@redhat.com; berrange@redhat.com; alistair.francis@xilinx.com; Pavel Dovgalyuk;
> Paolo Bonzini
> Subject: [PATCH v7 4/5] shutdown: Preserve shutdown cause through replay
> 
> With the recent addition of ShutdownCause, we want to be able to pass
> a cause through any shutdown request, and then faithfully replay that
> cause when later replaying the same sequence.  The easiest way is to
> expand the reply event mechanism to track a series of values for
> EVENT_SHUTDOWN, one corresponding to each value of ShutdownCause.
> 
> We are free to change the replay stream as needed, since there are
> already no guarantees about being able to use a replay stream by
> any other version of qemu than the one that generated it.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>

> 
> ---
> v7: rebase to context
> v6: new patch
> ---
>  include/sysemu/replay.h  |  3 ++-
>  include/sysemu/sysemu.h  |  1 +
>  replay/replay-internal.h |  3 ++-
>  vl.c                     |  3 +--
>  replay/replay.c          | 10 +++++-----
>  5 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
> index f1c0712..fa14d0e 100644
> --- a/include/sysemu/replay.h
> +++ b/include/sysemu/replay.h
> @@ -13,6 +13,7 @@
>   */
> 
>  #include "qapi-types.h"
> +#include "sysemu.h"
> 
>  /* replay clock kinds */
>  enum ReplayClockKind {
> @@ -98,7 +99,7 @@ int64_t replay_read_clock(ReplayClockKind kind);
>  /* Events */
> 
>  /*! Called when qemu shutdown is requested. */
> -void replay_shutdown_request(void);
> +void replay_shutdown_request(ShutdownCause cause);
>  /*! Should be called at check points in the execution.
>      These check points are skipped, if they were not met.
>      Saves checkpoint in the SAVE mode and validates in the PLAY mode.
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index fe197aa..e0cbab1 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -46,6 +46,7 @@ typedef enum ShutdownCause {
>                                       turns that into a shutdown */
>      SHUTDOWN_CAUSE_GUEST_PANIC,   /* Guest panicked, and command line turns
>                                       that into a shutdown */
> +    SHUTDOWN_CAUSE__MAX,
>  } ShutdownCause;
> 
>  void vm_start(void);
> diff --git a/replay/replay-internal.h b/replay/replay-internal.h
> index ed66ed8..3ebb199 100644
> --- a/replay/replay-internal.h
> +++ b/replay/replay-internal.h
> @@ -22,8 +22,9 @@ enum ReplayEvents {
>      EVENT_EXCEPTION,
>      /* for async events */
>      EVENT_ASYNC,
> -    /* for shutdown request */
> +    /* for shutdown requests, range allows recovery of ShutdownCause */
>      EVENT_SHUTDOWN,
> +    EVENT_SHUTDOWN_LAST = EVENT_SHUTDOWN + SHUTDOWN_CAUSE__MAX,
>      /* for character device write event */
>      EVENT_CHAR_WRITE,
>      /* for character device read all event */
> diff --git a/vl.c b/vl.c
> index 2d546460..65487d9 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1820,8 +1820,7 @@ void qemu_system_killed(int signal, pid_t pid)
>  void qemu_system_shutdown_request(ShutdownCause reason)
>  {
>      trace_qemu_system_shutdown_request(reason);
> -    /* FIXME - add a parameter to let replay preserve reason */
> -    replay_shutdown_request();
> +    replay_shutdown_request(reason);
>      shutdown_requested = reason;
>      qemu_notify_event();
>  }
> diff --git a/replay/replay.c b/replay/replay.c
> index 604fa4f..ff58a5a 100644
> --- a/replay/replay.c
> +++ b/replay/replay.c
> @@ -49,10 +49,10 @@ bool replay_next_event_is(int event)
>              res = true;
>          }
>          switch (replay_state.data_kind) {
> -        case EVENT_SHUTDOWN:
> +        case EVENT_SHUTDOWN ... EVENT_SHUTDOWN_LAST:
>              replay_finish_event();
> -            /* FIXME - store actual reason */
> -            qemu_system_shutdown_request(SHUTDOWN_CAUSE_HOST_ERROR);
> +            qemu_system_shutdown_request(replay_state.data_kind -
> +                                         EVENT_SHUTDOWN);
>              break;
>          default:
>              /* clock, time_t, checkpoint and other events */
> @@ -171,11 +171,11 @@ bool replay_has_interrupt(void)
>      return res;
>  }
> 
> -void replay_shutdown_request(void)
> +void replay_shutdown_request(ShutdownCause cause)
>  {
>      if (replay_mode == REPLAY_MODE_RECORD) {
>          replay_mutex_lock();
> -        replay_put_event(EVENT_SHUTDOWN);
> +        replay_put_event(EVENT_SHUTDOWN + cause);
>          replay_mutex_unlock();
>      }
>  }
> --
> 2.9.3