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virtio: introduce config op to synchronize vring callbacks

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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 <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: linux-s390@vger.kernel.org
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220527060120.20964-4-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
This commit is contained in:
Jason Wang 2022-05-27 14:01:14 +08:00 committed by Michael S. Tsirkin
parent 0aa96837c3
commit 48b69959a8
1 changed files with 25 additions and 0 deletions
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25
include/linux/virtio_config.h
View file

@ -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