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Diffstat (limited to 'include/linux/virtio_ring.h')
-rw-r--r-- | include/linux/virtio_ring.h | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h new file mode 100644 index 000000000..8b8af1a38 --- /dev/null +++ b/include/linux/virtio_ring.h @@ -0,0 +1,104 @@ +/* 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 */ |