Re: [Qemu-devel] [PATCH v4 06/13] 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>

Just a general thought; be careful when following migration states;
For example 'device' and 'pre_switchover' - just be careful to think
about all the different states and how you might get a 'failed'
anywhere.

Dave
> ---
>  hw/vfio/migration.c           | 49 +++++++++++++++++++++++++++++++++++++++++++
>  include/hw/vfio/vfio-common.h |  1 +
>  2 files changed, 50 insertions(+)
> 
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 15af218c23d1..7f9858e6c995 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -112,6 +112,48 @@ static void vfio_vmstate_change(void *opaque, int running, RunState state)
>      vbasedev->vm_running = running;
>  }
>  
> +static void vfio_migration_state_notifier(Notifier *notifier, void *data)
> +{
> +    MigrationState *s = data;
> +    VFIODevice *vbasedev = container_of(notifier, VFIODevice, migration_state);
> +    int ret;
> +
> +    switch (s->state) {
> +    case MIGRATION_STATUS_ACTIVE:
> +        if (vbasedev->device_state & VFIO_DEVICE_STATE_RUNNING) {
> +            if (vbasedev->vm_running) {
> +                ret = vfio_migration_set_state(vbasedev,
> +                          VFIO_DEVICE_STATE_RUNNING | VFIO_DEVICE_STATE_SAVING);
> +                if (ret) {
> +                    error_report("Failed to set state RUNNING and SAVING");
> +                }
> +            } else {
> +                ret = vfio_migration_set_state(vbasedev,
> +                                               VFIO_DEVICE_STATE_SAVING);
> +                if (ret) {
> +                    error_report("Failed to set state STOP and SAVING");
> +                }
> +            }
> +        } else {
> +            ret = vfio_migration_set_state(vbasedev,
> +                                           VFIO_DEVICE_STATE_RESUMING);
> +            if (ret) {
> +                error_report("Failed to set state RESUMING");
> +            }
> +        }
> +        return;
> +
> +    case MIGRATION_STATUS_CANCELLING:
> +    case MIGRATION_STATUS_CANCELLED:
> +    case MIGRATION_STATUS_FAILED:
> +        ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_RUNNING);
> +        if (ret) {
> +            error_report("Failed to set state RUNNING");
> +        }
> +        return;
> +    }
> +}
> +
>  static int vfio_migration_init(VFIODevice *vbasedev,
>                                 struct vfio_region_info *info)
>  {
> @@ -131,6 +173,9 @@ 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;
>  }
>  
> @@ -167,6 +212,10 @@ void vfio_migration_finalize(VFIODevice *vbasedev)
>          return;
>      }
>  
> +    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/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index f2392e97fa57..1d26e6be8d48 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -133,6 +133,7 @@ typedef struct VFIODevice {
>      uint32_t device_state;
>      VMChangeStateEntry *vm_state;
>      int vm_running;
> +    Notifier migration_state;
>  } VFIODevice;
>  
>  struct VFIODeviceOps {
> -- 
> 2.7.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK