| /* 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 custom layout. */ |
| struct virtqueue *__vring_new_virtqueue(unsigned int index, |
| struct vring vring, |
| struct virtio_device *vdev, |
| bool weak_barriers, |
| bool ctx, |
| bool (*notify)(struct virtqueue *), |
| void (*callback)(struct virtqueue *), |
| 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 */ |