Re: [PATCH v16 QEMU 07/16] vfio: Add migration state change notifier

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Kirti Wankhede (kwankhede@nvidia.com) wrote:
> Added migration state change notifier to get notification on migration state
> change. These states are translated to VFIO device state and conveyed to vendor
> driver.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> ---
>  hw/vfio/migration.c           | 29 +++++++++++++++++++++++++++++
>  hw/vfio/trace-events          |  1 +
>  include/hw/vfio/vfio-common.h |  1 +
>  3 files changed, 31 insertions(+)
> 
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index af9443c275fb..22ded9d28cf3 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -154,6 +154,27 @@ static void vfio_vmstate_change(void *opaque, int running, RunState state)
>      }
>  }
>  
> +static void vfio_migration_state_notifier(Notifier *notifier, void *data)
> +{
> +    MigrationState *s = data;
> +    VFIODevice *vbasedev = container_of(notifier, VFIODevice, migration_state);
> +    int ret;
> +
> +    trace_vfio_migration_state_notifier(vbasedev->name, s->state);

You might want to use MigrationStatus_str(s->status) to make that
readable.

> +    switch (s->state) {
> +    case MIGRATION_STATUS_CANCELLING:
> +    case MIGRATION_STATUS_CANCELLED:
> +    case MIGRATION_STATUS_FAILED:
> +        ret = vfio_migration_set_state(vbasedev,
> +                      ~(VFIO_DEVICE_STATE_SAVING | VFIO_DEVICE_STATE_RESUMING),
> +                      VFIO_DEVICE_STATE_RUNNING);
> +        if (ret) {
> +            error_report("%s: Failed to set state RUNNING", vbasedev->name);
> +        }

In the migration code we check to see if the VM was running prior to the
start of the migration before we start the CPUs going again (see
migration_iteration_finish):
    case MIGRATION_STATUS_FAILED:
    case MIGRATION_STATUS_CANCELLED:
    case MIGRATION_STATUS_CANCELLING:
        if (s->vm_was_running) {
            vm_start();
        } else {
            if (runstate_check(RUN_STATE_FINISH_MIGRATE)) {
                runstate_set(RUN_STATE_POSTMIGRATE);
            }

so if the guest was paused before a migration we don't falsely restart
it.  Maybe you need something similar?

Dave

> +    }
> +}
> +
>  static int vfio_migration_init(VFIODevice *vbasedev,
>                                 struct vfio_region_info *info)
>  {
> @@ -173,6 +194,9 @@ static int vfio_migration_init(VFIODevice *vbasedev,
>      vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change,
>                                                            vbasedev);
>  
> +    vbasedev->migration_state.notify = vfio_migration_state_notifier;
> +    add_migration_state_change_notifier(&vbasedev->migration_state);
> +
>      return 0;
>  }
>  
> @@ -211,6 +235,11 @@ add_blocker:
>  
>  void vfio_migration_finalize(VFIODevice *vbasedev)
>  {
> +
> +    if (vbasedev->migration_state.notify) {
> +        remove_migration_state_change_notifier(&vbasedev->migration_state);
> +    }
> +
>      if (vbasedev->vm_state) {
>          qemu_del_vm_change_state_handler(vbasedev->vm_state);
>      }
> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
> index 3d15bacd031a..69503228f20e 100644
> --- a/hw/vfio/trace-events
> +++ b/hw/vfio/trace-events
> @@ -148,3 +148,4 @@ vfio_display_edid_write_error(void) ""
>  vfio_migration_probe(char *name, uint32_t index) " (%s) Region %d"
>  vfio_migration_set_state(char *name, uint32_t state) " (%s) state %d"
>  vfio_vmstate_change(char *name, int running, const char *reason, uint32_t dev_state) " (%s) running %d reason %s device state %d"
> +vfio_migration_state_notifier(char *name, int state) " (%s) state %d"
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 3d18eb146b33..28f55f66d019 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -123,6 +123,7 @@ typedef struct VFIODevice {
>      VMChangeStateEntry *vm_state;
>      uint32_t device_state;
>      int vm_running;
> +    Notifier migration_state;
>  } VFIODevice;
>  
>  struct VFIODeviceOps {
> -- 
> 2.7.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK