LXR linux/include/linux/virtio

   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#ifdef CONFIG_SMP
  25static inline void virtio_mb(bool weak_barriers)
  26{
  27        if (weak_barriers)
  28                smp_mb();
  29        else
  30                mb();
  31}
  32
  33static inline void virtio_rmb(bool weak_barriers)
  34{
  35        if (weak_barriers)
  36                smp_rmb();
  37        else
  38                rmb();
  39}
  40
  41static inline void virtio_wmb(bool weak_barriers)
  42{
  43        if (weak_barriers)
  44                smp_wmb();
  45        else
  46                wmb();
  47}
  48#else
  49static inline void virtio_mb(bool weak_barriers)
  50{
  51        mb();
  52}
  53
  54static inline void virtio_rmb(bool weak_barriers)
  55{
  56        rmb();
  57}
  58
  59static inline void virtio_wmb(bool weak_barriers)
  60{
  61        wmb();
  62}
  63#endif
  64
  65struct virtio_device;
  66struct virtqueue;
  67
  68struct virtqueue *vring_new_virtqueue(unsigned int index,
  69                                      unsigned int num,
  70                                      unsigned int vring_align,
  71                                      struct virtio_device *vdev,
  72                                      bool weak_barriers,
  73                                      void *pages,
  74                                      bool (*notify)(struct virtqueue *vq),
  75                                      void (*callback)(struct virtqueue *vq),
  76                                      const char *name);
  77void vring_del_virtqueue(struct virtqueue *vq);
  78/* Filter out transport-specific feature bits. */
  79void vring_transport_features(struct virtio_device *vdev);
  80
  81irqreturn_t vring_interrupt(int irq, void *_vq);
  82#endif /* _LINUX_VIRTIO_RING_H */
  83