1 #ifndef _LINUX_VIRTIO_RING_H 2 #define _LINUX_VIRTIO_RING_H 3 4 #include <asm/barrier.h> 5 #include <linux/irqreturn.h> 6 #include <uapi/linux/virtio_ring.h> 7 8 /* 9 * Barriers in virtio are tricky. Non-SMP virtio guests can't assume 10 * they're not on an SMP host system, so they need to assume real 11 * barriers. Non-SMP virtio hosts could skip the barriers, but does 12 * anyone care? 13 * 14 * For virtio_pci on SMP, we don't need to order with respect to MMIO 15 * accesses through relaxed memory I/O windows, so smp_mb() et al are 16 * sufficient. 17 * 18 * For using virtio to talk to real devices (eg. other heterogeneous 19 * CPUs) we do need real barriers. In theory, we could be using both 20 * kinds of virtio, so it's a runtime decision, and the branch is 21 * actually quite cheap. 22 */ 23 24 static inline void virtio_mb(bool weak_barriers) 25 { 26 #ifdef CONFIG_SMP 27 if (weak_barriers) 28 smp_mb(); 29 else 30 #endif 31 mb(); 32 } 33 34 static inline void virtio_rmb(bool weak_barriers) 35 { 36 if (weak_barriers) 37 dma_rmb(); 38 else 39 rmb(); 40 } 41 42 static inline void virtio_wmb(bool weak_barriers) 43 { 44 if (weak_barriers) 45 dma_wmb(); 46 else 47 wmb(); 48 } 49 50 struct virtio_device; 51 struct virtqueue; 52 53 struct virtqueue *vring_new_virtqueue(unsigned int index, 54 unsigned int num, 55 unsigned int vring_align, 56 struct virtio_device *vdev, 57 bool weak_barriers, 58 void *pages, 59 bool (*notify)(struct virtqueue *vq), 60 void (*callback)(struct virtqueue *vq), 61 const char *name); 62 void vring_del_virtqueue(struct virtqueue *vq); 63 /* Filter out transport-specific feature bits. */ 64 void vring_transport_features(struct virtio_device *vdev); 65 66 irqreturn_t vring_interrupt(int irq, void *_vq); 67 #endif /* _LINUX_VIRTIO_RING_H */ 68