/* 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 */