On Fri, 27 May 2022 14:01:14 +0800, Jason Wang <[email protected]> wrote: > This patch introduces new virtio config op to vring > callbacks. Transport specific method is required to make sure the > write before this function is visible to the vring_interrupt() that is > called after the return of this function. For the transport that > doesn't provide synchronize_vqs(), use synchornize_rcu() which > synchronize with IRQ implicitly as a fallback. > > Cc: Thomas Gleixner <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: "Paul E. McKenney" <[email protected]> > Cc: Marc Zyngier <[email protected]> > Cc: Halil Pasic <[email protected]> > Cc: Cornelia Huck <[email protected]> > Cc: Vineeth Vijayan <[email protected]> > Cc: Peter Oberparleiter <[email protected]> > Cc: [email protected] > Reviewed-by: Cornelia Huck <[email protected]> > Signed-off-by: Jason Wang <[email protected]>
Reviewed-by: Xuan Zhuo <[email protected]> > --- > include/linux/virtio_config.h | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index b341dd62aa4d..25be018810a7 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -57,6 +57,11 @@ struct virtio_shm_region { > * include a NULL entry for vqs unused by driver > * Returns 0 on success or error status > * @del_vqs: free virtqueues found by find_vqs(). > + * @synchronize_cbs: synchronize with the virtqueue callbacks (optional) > + * The function guarantees that all memory operations on the > + * queue before it are visible to the vring_interrupt() that is > + * called after it. > + * vdev: the virtio_device > * @get_features: get the array of feature bits for this device. > * vdev: the virtio_device > * Returns the first 64 feature bits (all we currently need). > @@ -89,6 +94,7 @@ struct virtio_config_ops { > const char * const names[], const bool *ctx, > struct irq_affinity *desc); > void (*del_vqs)(struct virtio_device *); > + void (*synchronize_cbs)(struct virtio_device *); > u64 (*get_features)(struct virtio_device *vdev); > int (*finalize_features)(struct virtio_device *vdev); > const char *(*bus_name)(struct virtio_device *vdev); > @@ -217,6 +223,25 @@ int virtio_find_vqs_ctx(struct virtio_device *vdev, > unsigned nvqs, > desc); > } > > +/** > + * virtio_synchronize_cbs - synchronize with virtqueue callbacks > + * @vdev: the device > + */ > +static inline > +void virtio_synchronize_cbs(struct virtio_device *dev) > +{ > + if (dev->config->synchronize_cbs) { > + dev->config->synchronize_cbs(dev); > + } else { > + /* > + * A best effort fallback to synchronize with > + * interrupts, preemption and softirq disabled > + * regions. See comment above synchronize_rcu(). > + */ > + synchronize_rcu(); > + } > +} > + > /** > * virtio_device_ready - enable vq use in probe function > * @vdev: the device > -- > 2.25.1 > _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
