Re: [Qemu-devel] [PATCH v7 12/42] Migration commands

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Create QEMU_VM_COMMAND section type for sending commands from
> source to destination.  These commands are not intended to convey
> guest state but to control the migration process.
>
> For use in postcopy.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
>  include/migration/migration.h |  1 +
>  include/sysemu/sysemu.h       |  7 +++++++
>  migration/savevm.c            | 46 
> +++++++++++++++++++++++++++++++++++++++++++
>  trace-events                  |  1 +
>  4 files changed, 55 insertions(+)
>
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 414c5cf..8adaa45 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -34,6 +34,7 @@
>  #define QEMU_VM_SECTION_FULL         0x04
>  #define QEMU_VM_SUBSECTION           0x05
>  #define QEMU_VM_VMDESCRIPTION        0x06
> +#define QEMU_VM_COMMAND              0x07

conflicts with configuration section just sent

>  #define QEMU_VM_SECTION_FOOTER       0x7e
>  
>  struct MigrationParams {
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index 6dae2db..5869607 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -82,6 +82,11 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict);
>  
>  void qemu_announce_self(void);
>  
> +/* Subcommands for QEMU_VM_COMMAND */
> +enum qemu_vm_cmd {
> +    MIG_CMD_INVALID = 0,   /* Must be 0 */
> +};
> +
>  bool qemu_savevm_state_blocked(Error **errp);
>  void qemu_savevm_state_begin(QEMUFile *f,
>                               const MigrationParams *params);
> @@ -90,6 +95,8 @@ int qemu_savevm_state_iterate(QEMUFile *f);
>  void qemu_savevm_state_complete_precopy(QEMUFile *f);
>  void qemu_savevm_state_cancel(void);
>  uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size);
> +void qemu_savevm_command_send(QEMUFile *f, enum qemu_vm_cmd command,
> +                              uint16_t len, uint8_t *data);
>  int qemu_loadvm_state(QEMUFile *f);
>  
>  typedef enum DisplayType
> diff --git a/migration/savevm.c b/migration/savevm.c
> index f9168ac..7ce9d21 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -686,6 +686,23 @@ static bool check_section_footer(QEMUFile *f, 
> SaveStateEntry *se)
>      return true;
>  }
>  
> +/* Send a 'QEMU_VM_COMMAND' type element with the command
> + * and associated data.

Please, use doxygen comments for new functions :p


> + */
> +void qemu_savevm_command_send(QEMUFile *f,
> +                              enum qemu_vm_cmd command,
> +                              uint16_t len,
> +                              uint8_t *data)
> +{
> +    qemu_put_byte(f, QEMU_VM_COMMAND);
> +    qemu_put_be16(f, (uint16_t)command);
> +    qemu_put_be16(f, len);
> +    if (len) {
> +        qemu_put_buffer(f, data, len);
> +    }
> +    qemu_fflush(f);
> +}
> +
>  bool qemu_savevm_state_blocked(Error **errp)
>  {
>      SaveStateEntry *se;
> @@ -982,6 +999,29 @@ static SaveStateEntry *find_se(const char *idstr, int 
> instance_id)
>      return NULL;
>  }
>  
> +/*
> + * Process an incoming 'QEMU_VM_COMMAND'
> + * negative return on error (will issue error message)
> + */
> +static int loadvm_process_command(QEMUFile *f)
> +{
> +    uint16_t cmd;
> +    uint16_t len;
> +
> +    cmd = qemu_get_be16(f);
> +    len = qemu_get_be16(f);
> +
> +    trace_loadvm_process_command(cmd, len);

trace for load but not for sending?

> +    switch (cmd) {
> +
> +    default:
> +        error_report("VM_COMMAND 0x%x unknown (len 0x%x)", cmd, len);
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
>  struct LoadStateEntry {
>      QLIST_ENTRY(LoadStateEntry) entry;
>      SaveStateEntry *se;
> @@ -1114,6 +1154,12 @@ int qemu_loadvm_state(QEMUFile *f)
>                  goto out;
>              }
>              break;
> +        case QEMU_VM_COMMAND:
> +            ret = loadvm_process_command(f);
> +            if (ret < 0) {
> +                goto out;
> +            }
> +            break;
>          default:
>              error_report("Unknown savevm section type %d", section_type);
>              ret = -EINVAL;
> diff --git a/trace-events b/trace-events
> index d539528..73a65c3 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -1183,6 +1183,7 @@ virtio_gpu_fence_resp(uint64_t fence) "fence 0x%" PRIx64
>  qemu_loadvm_state_section(unsigned int section_type) "%d"
>  qemu_loadvm_state_section_partend(uint32_t section_id) "%u"
>  qemu_loadvm_state_section_startfull(uint32_t section_id, const char *idstr, 
> uint32_t instance_id, uint32_t version_id) "%u(%s) %u %u"
> +loadvm_process_command(uint16_t com, uint16_t len) "com=0x%x len=%d"
>  savevm_section_start(const char *id, unsigned int section_id) "%s, 
> section_id %u"
>  savevm_section_end(const char *id, unsigned int section_id, int ret) "%s, 
> section_id %u -> %d"
>  savevm_state_begin(void) ""