Re: [Qemu-devel] [PATCH v4 05/13] vfio: Add VM state change handler to know state of VM

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

* Kirti Wankhede (kwankhede@nvidia.com) wrote:
> VM state change handler gets called on change in VM's state. This is used to set
> VFIO device state to _RUNNING.
> VM state change handler, migration state change handler and log_sync listener
> are called asynchronously, which sometimes lead to data corruption in migration
> region. Initialised mutex that is used to serialize operations on migration data
> region during saving state.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>


> ---
>  hw/vfio/migration.c           | 45 +++++++++++++++++++++++++++++++++++++++++++
>  include/hw/vfio/vfio-common.h |  4 ++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index ba58d9253d26..15af218c23d1 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -77,6 +77,41 @@ err:
>      return ret;
>  }
>  
> +static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t state)
> +{
> +    VFIOMigration *migration = vbasedev->migration;
> +    VFIORegion *region = &migration->region.buffer;
> +    int ret = 0;
> +
> +    ret = pwrite(vbasedev->fd, &state, sizeof(state),
> +                 region->fd_offset + offsetof(struct vfio_device_migration_info,
> +                                              device_state));
> +    if (ret < 0) {
> +        error_report("Failed to set migration state %d %s",
> +                     ret, strerror(errno));

Please include the device name/id in errors; it just makes it easier to
figure out the cause when someone sends me a log.

Other than that;


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> +        return ret;
> +    }
> +
> +    vbasedev->device_state = state;
> +    return 0;
> +}
> +
> +static void vfio_vmstate_change(void *opaque, int running, RunState state)
> +{
> +    VFIODevice *vbasedev = opaque;
> +
> +    if ((vbasedev->vm_running != running) && running) {
> +        int ret;
> +
> +        ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_RUNNING);
> +        if (ret) {
> +            error_report("Failed to set state RUNNING");
> +        }
> +    }
> +
> +    vbasedev->vm_running = running;
> +}
> +
>  static int vfio_migration_init(VFIODevice *vbasedev,
>                                 struct vfio_region_info *info)
>  {
> @@ -91,6 +126,11 @@ static int vfio_migration_init(VFIODevice *vbasedev,
>          return ret;
>      }
>  
> +    qemu_mutex_init(&vbasedev->migration->lock);
> +
> +    vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change,
> +                                                          vbasedev);
> +
>      return 0;
>  }
>  
> @@ -127,11 +167,16 @@ void vfio_migration_finalize(VFIODevice *vbasedev)
>          return;
>      }
>  
> +    if (vbasedev->vm_state) {
> +        qemu_del_vm_change_state_handler(vbasedev->vm_state);
> +    }
> +
>      if (vbasedev->migration_blocker) {
>          migrate_del_blocker(vbasedev->migration_blocker);
>          error_free(vbasedev->migration_blocker);
>      }
>  
> +    qemu_mutex_destroy(&vbasedev->migration->lock);
>      vfio_migration_region_exit(vbasedev);
>      g_free(vbasedev->migration);
>  }
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 1374a03470d8..f2392e97fa57 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -29,6 +29,7 @@
>  #ifdef CONFIG_LINUX
>  #include <linux/vfio.h>
>  #endif
> +#include "sysemu/sysemu.h"
>  
>  #define VFIO_MSG_PREFIX "vfio %s: "
>  
> @@ -129,6 +130,9 @@ typedef struct VFIODevice {
>      unsigned int flags;
>      VFIOMigration *migration;
>      Error *migration_blocker;
> +    uint32_t device_state;
> +    VMChangeStateEntry *vm_state;
> +    int vm_running;
>  } VFIODevice;
>  
>  struct VFIODeviceOps {
> -- 
> 2.7.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK