Re: [Qemu-devel] [PATCH 1/8] Introduce the VMStatus type

[Kevin Wolf <kwolf@redhat.com>]

Am 12.07.2011 16:25, schrieb Luiz Capitulino:
> On Tue, 12 Jul 2011 09:28:05 +0200
> Markus Armbruster <armbru@redhat.com> wrote:
> 
>> Luiz Capitulino <lcapitulino@redhat.com> writes:
>>
>>> We need to track the VM status so that QMP can report it to clients.
>>>
>>> This commit adds the VMStatus type and related functions. The
>>> vm_status_set() function is used to keep track of the current
>>> VM status.
>>>
>>> The current statuses are:
>>
>> Nitpicking about names, bear with me.
>>
>>>     - debug: guest is running under gdb
>>>     - inmigrate: guest is paused waiting for an incoming migration
>>
>> incoming-migration?
>>
>>>     - postmigrate: guest is paused following a successful migration
>>
>> post-migrate?
>>
>>>     - internal-error: Fatal internal error that prevents further guest
>>>                 execution
>>>     - load-state-error: guest is paused following a failed 'loadvm'
>>
>> Less than obvious.  If you like concrete, name it loadvm-failed.  If you
>> like abstract, name it restore-vm-failed.
> 
> Ok for your suggestions above.
> 
>>
>>>     - io-error: the last IOP has failed and the device is configured
>>>                 to pause on I/O errors
>>>     - watchdog-error: the watchdog action is configured to pause and
>>>                       has been triggered
>>
>> Sounds like the watchdog suffered an error.  watchdog-fired?
> 
> Maybe watchdog-paused.
> 
>>
>>>     - paused: guest has been paused via the 'stop' command
>>
>> stop-command?
> 
> I prefer 'paused', it communicates better the state we're in.
> 
>>
>>>     - prelaunch: QEMU was started with -S and guest has not started
>>
>> unstarted?
> 
> Looks the same to me.
> 
>>
>>>     - running: guest is actively running
>>>     - shutdown: guest is shut down (and -no-shutdown is in use)
>>>
>>> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
>>> ---
>>>  gdbstub.c       |    4 ++++
>>>  hw/ide/core.c   |    1 +
>>>  hw/scsi-disk.c  |    1 +
>>>  hw/virtio-blk.c |    1 +
>>>  hw/watchdog.c   |    1 +
>>>  kvm-all.c       |    1 +
>>>  migration.c     |    3 +++
>>>  monitor.c       |    5 ++++-
>>>  sysemu.h        |   19 +++++++++++++++++++
>>>  vl.c            |   37 +++++++++++++++++++++++++++++++++++++
>>>  10 files changed, 72 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/gdbstub.c b/gdbstub.c
>>> index c085a5a..61b700a 100644
>>> --- a/gdbstub.c
>>> +++ b/gdbstub.c
>>> @@ -2358,6 +2358,7 @@ void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...)
>>>      s->state = RS_SYSCALL;
>>>  #ifndef CONFIG_USER_ONLY
>>>      vm_stop(VMSTOP_DEBUG);
>>> +    vm_status_set(VMST_DEBUG);
>>>  #endif
>>>      s->state = RS_IDLE;
>>>      va_start(va, fmt);
>>> @@ -2432,6 +2433,7 @@ static void gdb_read_byte(GDBState *s, int ch)
>>>          /* when the CPU is running, we cannot do anything except stop
>>>             it when receiving a char */
>>>          vm_stop(VMSTOP_USER);
>>> +        vm_status_set(VMST_DEBUG);
>>>      } else
>>>  #endif
>>>      {
>>> @@ -2694,6 +2696,7 @@ static void gdb_chr_event(void *opaque, int event)
>>>      switch (event) {
>>>      case CHR_EVENT_OPENED:
>>>          vm_stop(VMSTOP_USER);
>>> +        vm_status_set(VMST_DEBUG);
>>>          gdb_has_xml = 0;
>>>          break;
>>>      default:
>>
>> Previous hunk has VMST_DEBUG with VMST_DEBUG.  Odd.
>>
>>> @@ -2735,6 +2738,7 @@ static void gdb_sigterm_handler(int signal)
>>>  {
>>>      if (vm_running) {
>>>          vm_stop(VMSTOP_USER);
>>> +        vm_status_set(VMST_DEBUG);
>>>      }
>>>  }
>>>  #endif
>>> diff --git a/hw/ide/core.c b/hw/ide/core.c
>>> index ca17a43..bf9df41 100644
>>> --- a/hw/ide/core.c
>>> +++ b/hw/ide/core.c
>>> @@ -523,6 +523,7 @@ static int ide_handle_rw_error(IDEState *s, int error, int op)
>>>          s->bus->error_status = op;
>>>          bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);
>>>          vm_stop(VMSTOP_DISKFULL);
>>> +        vm_status_set(VMST_IOERROR);
>>>      } else {
>>>          if (op & BM_STATUS_DMA_RETRY) {
>>>              dma_buf_commit(s, 0);
>>> diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
>>> index a8c7372..66037fd 100644
>>> --- a/hw/scsi-disk.c
>>> +++ b/hw/scsi-disk.c
>>> @@ -216,6 +216,7 @@ static int scsi_handle_rw_error(SCSIDiskReq *r, int error, int type)
>>>  
>>>          bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);
>>>          vm_stop(VMSTOP_DISKFULL);
>>> +        vm_status_set(VMST_IOERROR);
>>>      } else {
>>>          if (type == SCSI_REQ_STATUS_RETRY_READ) {
>>>              scsi_req_data(&r->req, 0);
>>> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
>>> index 91e0394..bf70200 100644
>>> --- a/hw/virtio-blk.c
>>> +++ b/hw/virtio-blk.c
>>> @@ -79,6 +79,7 @@ static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
>>>          s->rq = req;
>>>          bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);
>>>          vm_stop(VMSTOP_DISKFULL);
>>> +        vm_status_set(VMST_IOERROR);
>>>      } else {
>>>          virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
>>>          bdrv_mon_event(s->bs, BDRV_ACTION_REPORT, is_read);
>>> diff --git a/hw/watchdog.c b/hw/watchdog.c
>>> index 1c900a1..d130cbb 100644
>>> --- a/hw/watchdog.c
>>> +++ b/hw/watchdog.c
>>> @@ -133,6 +133,7 @@ void watchdog_perform_action(void)
>>>      case WDT_PAUSE:             /* same as 'stop' command in monitor */
>>>          watchdog_mon_event("pause");
>>>          vm_stop(VMSTOP_WATCHDOG);
>>> +        vm_status_set(VMST_WATCHDOG);
>>>          break;
>>>  
>>>      case WDT_DEBUG:
>>> diff --git a/kvm-all.c b/kvm-all.c
>>> index cbc2532..aee9e0a 100644
>>> --- a/kvm-all.c
>>> +++ b/kvm-all.c
>>> @@ -1015,6 +1015,7 @@ int kvm_cpu_exec(CPUState *env)
>>>      if (ret < 0) {
>>>          cpu_dump_state(env, stderr, fprintf, CPU_DUMP_CODE);
>>>          vm_stop(VMSTOP_PANIC);
>>> +        vm_status_set(VMST_INTERROR);
>>>      }
>>>  
>>>      env->exit_request = 0;
>>> diff --git a/migration.c b/migration.c
>>> index af3a1f2..674792f 100644
>>> --- a/migration.c
>>> +++ b/migration.c
>>> @@ -394,6 +394,9 @@ void migrate_fd_put_ready(void *opaque)
>>>              }
>>>              state = MIG_STATE_ERROR;
>>>          }
>>> +        if (state == MIG_STATE_COMPLETED) {
>>> +            vm_status_set(VMST_POSTMIGRATE);
>>> +        }
>>>          s->state = state;
>>>          notifier_list_notify(&migration_state_notifiers);
>>>      }
>>> diff --git a/monitor.c b/monitor.c
>>> index 67ceb46..1cb3191 100644
>>> --- a/monitor.c
>>> +++ b/monitor.c
>>> @@ -1258,6 +1258,7 @@ static void do_singlestep(Monitor *mon, const QDict *qdict)
>>>  static int do_stop(Monitor *mon, const QDict *qdict, QObject **ret_data)
>>>  {
>>>      vm_stop(VMSTOP_USER);
>>> +    vm_status_set(VMST_PAUSED);
>>>      return 0;
>>>  }
>>>  
>>> @@ -2782,7 +2783,9 @@ static void do_loadvm(Monitor *mon, const QDict *qdict)
>>>  
>>>      vm_stop(VMSTOP_LOADVM);
>>>  
>>> -    if (load_vmstate(name) == 0 && saved_vm_running) {
>>> +    if (load_vmstate(name) < 0) {
>>> +        vm_status_set(VMST_LOADERROR);
>>> +    } else if (saved_vm_running) {
>>>          vm_start();
>>>      }
>>>  }
>>> diff --git a/sysemu.h b/sysemu.h
>>> index d3013f5..7308ac5 100644
>>> --- a/sysemu.h
>>> +++ b/sysemu.h
>>> @@ -77,6 +77,25 @@ int qemu_savevm_state_complete(Monitor *mon, QEMUFile *f);
>>>  void qemu_savevm_state_cancel(Monitor *mon, QEMUFile *f);
>>>  int qemu_loadvm_state(QEMUFile *f);
>>>  
>>> +typedef enum {
>>> +    VMST_NOSTATUS,
>>> +    VMST_DEBUG,
>>> +    VMST_INMIGRATE,
>>> +    VMST_POSTMIGRATE,
>>> +    VMST_INTERROR,
>>> +    VMST_IOERROR,
>>> +    VMST_LOADERROR,
>>> +    VMST_PAUSED,
>>> +    VMST_PRELAUNCH,
>>> +    VMST_RUNNING,
>>> +    VMST_SHUTDOWN,
>>> +    VMST_WATCHDOG,
>>> +    VMST_MAX,
>>> +} VMStatus;
>>
>> How are these related to the VMSTOP_*?
>>
>> Why do we need a separate enumeration?

Luiz, what about this part? For me, this was the most important
question. We already have VMSTOP_*, and every caller of vm_stop() should
change the status (most of the vm_status_set() calls come immediately
after a vm_stop() call), so it would appear logical that vm_stop(),
which already gets a reason, sets the status.

Probably we would need a few additional reasons for vm_stop(), but
keeping two separate status values for almost the same thing looks
suspicious.

Kevin