| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef _LINUX_VIRTIO_RING_H |
| 3 | #define _LINUX_VIRTIO_RING_H |
| 4 | |
| 5 | #include <asm/barrier.h> |
| 6 | #include <linux/irqreturn.h> |
| 7 | #include <uapi/linux/virtio_ring.h> |
| 8 | |
| 9 | /* |
| 10 | * Barriers in virtio are tricky. Non-SMP virtio guests can't assume |
| 11 | * they're not on an SMP host system, so they need to assume real |
| 12 | * barriers. Non-SMP virtio hosts could skip the barriers, but does |
| 13 | * anyone care? |
| 14 | * |
| 15 | * For virtio_pci on SMP, we don't need to order with respect to MMIO |
| 16 | * accesses through relaxed memory I/O windows, so virt_mb() et al are |
| 17 | * sufficient. |
| 18 | * |
| 19 | * For using virtio to talk to real devices (eg. other heterogeneous |
| 20 | * CPUs) we do need real barriers. In theory, we could be using both |
| 21 | * kinds of virtio, so it's a runtime decision, and the branch is |
| 22 | * actually quite cheap. |
| 23 | */ |
| 24 | |
| 25 | static inline void virtio_mb(bool weak_barriers) |
| 26 | { |
| 27 | if (weak_barriers) |
| 28 | virt_mb(); |
| 29 | else |
| 30 | mb(); |
| 31 | } |
| 32 | |
| 33 | static inline void virtio_rmb(bool weak_barriers) |
| 34 | { |
| 35 | if (weak_barriers) |
| 36 | virt_rmb(); |
| 37 | else |
| 38 | dma_rmb(); |
| 39 | } |
| 40 | |
| 41 | static inline void virtio_wmb(bool weak_barriers) |
| 42 | { |
| 43 | if (weak_barriers) |
| 44 | virt_wmb(); |
| 45 | else |
| 46 | dma_wmb(); |
| 47 | } |
| 48 | |
| Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame] | 49 | #define virtio_store_mb(weak_barriers, p, v) \ |
| 50 | do { \ |
| 51 | if (weak_barriers) { \ |
| 52 | virt_store_mb(*p, v); \ |
| 53 | } else { \ |
| 54 | WRITE_ONCE(*p, v); \ |
| 55 | mb(); \ |
| 56 | } \ |
| 57 | } while (0) \ |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 58 | |
| 59 | struct virtio_device; |
| 60 | struct virtqueue; |
| 61 | |
| 62 | /* |
| 63 | * Creates a virtqueue and allocates the descriptor ring. If |
| 64 | * may_reduce_num is set, then this may allocate a smaller ring than |
| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 65 | * expected. The caller should query virtqueue_get_vring_size to learn |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 66 | * the actual size of the ring. |
| 67 | */ |
| 68 | struct virtqueue *vring_create_virtqueue(unsigned int index, |
| 69 | unsigned int num, |
| 70 | unsigned int vring_align, |
| 71 | struct virtio_device *vdev, |
| 72 | bool weak_barriers, |
| 73 | bool may_reduce_num, |
| 74 | bool ctx, |
| 75 | bool (*notify)(struct virtqueue *vq), |
| 76 | void (*callback)(struct virtqueue *vq), |
| 77 | const char *name); |
| 78 | |
| 79 | /* Creates a virtqueue with a custom layout. */ |
| 80 | struct virtqueue *__vring_new_virtqueue(unsigned int index, |
| 81 | struct vring vring, |
| 82 | struct virtio_device *vdev, |
| 83 | bool weak_barriers, |
| 84 | bool ctx, |
| 85 | bool (*notify)(struct virtqueue *), |
| 86 | void (*callback)(struct virtqueue *), |
| 87 | const char *name); |
| 88 | |
| 89 | /* |
| 90 | * Creates a virtqueue with a standard layout but a caller-allocated |
| 91 | * ring. |
| 92 | */ |
| 93 | struct virtqueue *vring_new_virtqueue(unsigned int index, |
| 94 | unsigned int num, |
| 95 | unsigned int vring_align, |
| 96 | struct virtio_device *vdev, |
| 97 | bool weak_barriers, |
| 98 | bool ctx, |
| 99 | void *pages, |
| 100 | bool (*notify)(struct virtqueue *vq), |
| 101 | void (*callback)(struct virtqueue *vq), |
| 102 | const char *name); |
| 103 | |
| 104 | /* |
| 105 | * Destroys a virtqueue. If created with vring_create_virtqueue, this |
| 106 | * also frees the ring. |
| 107 | */ |
| 108 | void vring_del_virtqueue(struct virtqueue *vq); |
| 109 | |
| 110 | /* Filter out transport-specific feature bits. */ |
| 111 | void vring_transport_features(struct virtio_device *vdev); |
| 112 | |
| 113 | irqreturn_t vring_interrupt(int irq, void *_vq); |
| 114 | #endif /* _LINUX_VIRTIO_RING_H */ |