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- /* SPDX-License-Identifier: GPL-2.0 */
- #ifndef _LINUX_VIRTIO_RING_H
- #define _LINUX_VIRTIO_RING_H
- #include <asm/barrier.h>
- #include <linux/irqreturn.h>
- #include <uapi/linux/virtio_ring.h>
- /*
- * Barriers in virtio are tricky. Non-SMP virtio guests can't assume
- * they're not on an SMP host system, so they need to assume real
- * barriers. Non-SMP virtio hosts could skip the barriers, but does
- * anyone care?
- *
- * For virtio_pci on SMP, we don't need to order with respect to MMIO
- * accesses through relaxed memory I/O windows, so virt_mb() et al are
- * sufficient.
- *
- * For using virtio to talk to real devices (eg. other heterogeneous
- * CPUs) we do need real barriers. In theory, we could be using both
- * kinds of virtio, so it's a runtime decision, and the branch is
- * actually quite cheap.
- */
- static inline void virtio_mb(bool weak_barriers)
- {
- if (weak_barriers)
- virt_mb();
- else
- mb();
- }
- static inline void virtio_rmb(bool weak_barriers)
- {
- if (weak_barriers)
- virt_rmb();
- else
- dma_rmb();
- }
- static inline void virtio_wmb(bool weak_barriers)
- {
- if (weak_barriers)
- virt_wmb();
- else
- dma_wmb();
- }
- #define virtio_store_mb(weak_barriers, p, v) \
- do { \
- if (weak_barriers) { \
- virt_store_mb(*p, v); \
- } else { \
- WRITE_ONCE(*p, v); \
- mb(); \
- } \
- } while (0) \
- struct virtio_device;
- struct virtqueue;
- /*
- * Creates a virtqueue and allocates the descriptor ring. If
- * may_reduce_num is set, then this may allocate a smaller ring than
- * expected. The caller should query virtqueue_get_vring_size to learn
- * the actual size of the ring.
- */
- struct virtqueue *vring_create_virtqueue(unsigned int index,
- unsigned int num,
- unsigned int vring_align,
- struct virtio_device *vdev,
- bool weak_barriers,
- bool may_reduce_num,
- bool ctx,
- bool (*notify)(struct virtqueue *vq),
- void (*callback)(struct virtqueue *vq),
- const char *name);
- /*
- * Creates a virtqueue with a standard layout but a caller-allocated
- * ring.
- */
- struct virtqueue *vring_new_virtqueue(unsigned int index,
- unsigned int num,
- unsigned int vring_align,
- struct virtio_device *vdev,
- bool weak_barriers,
- bool ctx,
- void *pages,
- bool (*notify)(struct virtqueue *vq),
- void (*callback)(struct virtqueue *vq),
- const char *name);
- /*
- * Destroys a virtqueue. If created with vring_create_virtqueue, this
- * also frees the ring.
- */
- void vring_del_virtqueue(struct virtqueue *vq);
- /* Filter out transport-specific feature bits. */
- void vring_transport_features(struct virtio_device *vdev);
- irqreturn_t vring_interrupt(int irq, void *_vq);
- #endif /* _LINUX_VIRTIO_RING_H */
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