Re: [PATCH V1 14/32] savevm: VMS_RESTART and cprsave restart

[Steven Sistare <steven.sistare@oracle.com>]

On 9/11/2020 2:44 PM, Dr. David Alan Gilbert wrote:
> * Steve Sistare (steven.sistare@oracle.com) wrote:
>> Add the VMS_RESTART variant of vmstate, for use when upgrading qemu in place
>> on the same host without a reboot.  Invoke it using:
>>   cprsave <filename> restart
>>
>> VMS_RESTART supports guest ram mapped by private anonymous memory, versus
>> VMS_REBOOT which requires that guest ram be mapped by persistent shared
>> memory.  Subsequent patches complete its implementation.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> 
> You should find with the enum like Eric suggests this mostly disappears;
> but also you might want to put it after the patches that implement it.

Sure.  If this gets too small I will add it to the implementation patch.
I cannot move this after the impl, because the impl has additional uses of VMS_RESTART.

- Steve

>> ---
>>  hmp-commands.hx             | 4 +++-
>>  include/migration/vmstate.h | 1 +
>>  migration/savevm.c          | 4 +++-
>>  monitor/qmp-cmds.c          | 2 +-
>>  qapi/migration.json         | 1 +
>>  5 files changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/hmp-commands.hx b/hmp-commands.hx
>> index 7517876..11a2089 100644
>> --- a/hmp-commands.hx
>> +++ b/hmp-commands.hx
>> @@ -369,7 +369,7 @@ ERST
>>      {
>>          .name       = "cprsave",
>>          .args_type  = "file:s,mode:s",
>> -        .params     = "file 'reboot'",
>> +        .params     = "file 'restart'|'reboot'",
>>          .help       = "create a checkpoint of the VM in file",
>>          .cmd        = hmp_cprsave,
>>      },
>> @@ -380,6 +380,8 @@ SRST
>>    in *file*.
>>    If *mode* is 'reboot', the checkpoint can be cprload'ed after a host kexec
>>    reboot.
>> +  If *mode* is 'restart', the checkpoint can be cprload'ed after restarting
>> +  qemu.
>>    exec() /usr/bin/qemu-exec if it exists, else exec /usr/bin/qemu-system-x86_64,
>>    passing all the original command line arguments.  The VCPUs remain paused.
>>  ERST
>> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
>> index c58551a..8239b84 100644
>> --- a/include/migration/vmstate.h
>> +++ b/include/migration/vmstate.h
>> @@ -162,6 +162,7 @@ typedef enum {
>>      VMS_MIGRATE  = (1U << 1),
>>      VMS_SNAPSHOT = (1U << 2),
>>      VMS_REBOOT   = (1U << 3),
>> +    VMS_RESTART  = (1U << 4),
>>      VMS_MODE_ALL = ~0U
>>  } VMStateMode;
>>  
>> diff --git a/migration/savevm.c b/migration/savevm.c
>> index 00f493b..38cc63a 100644
>> --- a/migration/savevm.c
>> +++ b/migration/savevm.c
>> @@ -2708,6 +2708,8 @@ void save_cpr_snapshot(const char *file, const char *mode, Error **errp)
>>  
>>      if (!strcmp(mode, "reboot")) {
>>          op = VMS_REBOOT;
>> +    } else if (!strcmp(mode, "restart")) {
>> +        op = VMS_RESTART;
>>      } else {
>>          error_setg(errp, "cprsave: bad mode %s", mode);
>>          return;
>> @@ -2973,7 +2975,7 @@ void load_cpr_snapshot(const char *file, Error **errp)
>>          return;
>>      }
>>  
>> -    ret = qemu_loadvm_state(f, VMS_REBOOT);
>> +    ret = qemu_loadvm_state(f, VMS_REBOOT | VMS_RESTART);
>>      qemu_fclose(f);
>>      if (ret < 0) {
>>          error_setg(errp, "Error %d while loading VM state", ret);
>> diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
>> index 8c400e6..8a74c6e 100644
>> --- a/monitor/qmp-cmds.c
>> +++ b/monitor/qmp-cmds.c
>> @@ -164,7 +164,7 @@ void qmp_cont(Error **errp)
>>  
>>  char *qmp_cprinfo(Error **errp)
>>  {
>> -    return g_strdup("reboot");
>> +    return g_strdup("reboot restart");
>>  }
>>  
>>  void qmp_cprsave(const char *file, const char *mode, Error **errp)
>> diff --git a/qapi/migration.json b/qapi/migration.json
>> index 8190b16..d22992b 100644
>> --- a/qapi/migration.json
>> +++ b/qapi/migration.json
>> @@ -1639,6 +1639,7 @@
>>  #
>>  # @file: name of checkpoint file
>>  # @mode: 'reboot' : checkpoint can be cprload'ed after a host kexec reboot.
>> +#        'restart': checkpoint can be cprload'ed after restarting qemu.
>>  #
>>  # Since 5.0
>>  ##
>> -- 
>> 1.8.3.1
>>