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