Re: [PATCH v26 06/17] vfio: Add migration state change notifier

[Kirti Wankhede]

On 9/26/2020 1:50 AM, Alex Williamson wrote:
> On Wed, 23 Sep 2020 04:54:08 +0530
> 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>
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >   hw/vfio/migration.c           | 29 +++++++++++++++++++++++++++++
> >   hw/vfio/trace-events          |  5 +++--
> >   include/hw/vfio/vfio-common.h |  1 +
> >   3 files changed, 33 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> > index a30d628ba963..f650fe9fc3c8 100644
> > --- a/hw/vfio/migration.c
> > +++ b/hw/vfio/migration.c
> > @@ -199,6 +199,28 @@ 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,
> > +                                        MigrationStatus_str(s->state));
> > +
> > +    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);
> > +        }
>
> Here again the caller assumes success means the device has entered the
> desired state, but as implemented it only means the device is in some
> non-error state.
>
> > +    }
> > +}
> > +
> >   static int vfio_migration_init(VFIODevice *vbasedev,
> >                                  struct vfio_region_info *info)
> >   {
> > @@ -221,6 +243,8 @@ 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 ret;
> >   }
> >   
> > @@ -263,6 +287,11 @@ 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 6524734bf7b4..bcb3fa7314d7 100644
> > --- a/hw/vfio/trace-events
> > +++ b/hw/vfio/trace-events
> > @@ -149,5 +149,6 @@ vfio_display_edid_write_error(void) ""
> >   
> >   # migration.c
> >   vfio_migration_probe(const 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_set_state(const char *name, uint32_t state) " (%s) state %d"
> > +vfio_vmstate_change(const char *name, int running, const char *reason, uint32_t 
> > dev_state) " (%s) running %d reason %s device state %d"
> > +vfio_migration_state_notifier(const char *name, const char *state) " (%s) state 
> > %s"
> > diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> > index 25e3b1a3b90a..49c7c7a0e29a 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;
>
> Can this live in VFIOMigration?  Thanks,

No, callback vfio_migration_state_notifier() has notifier argument and 
to reach its corresponding device structure as below, its should be in 
VFIODevice.

VFIODevice *vbasedev = container_of(notifier, VFIODevice, migration_state);

Thanks,
Kirti

> Alex
>
> >   } VFIODevice;
> >   
> >   struct VFIODeviceOps {