diff options
| author | Michael S. Tsirkin | 2011-05-20 02:10:17 +0300 |
|---|---|---|
| committer | Rusty Russell | 2011-05-30 11:14:14 +0930 |
| commit | 770b31a85e000b0194974922f238a30ade4246b6 (patch) | |
| tree | eed81e23f3116858b49af76bcc5831c38662de96 | |
| parent | a1b383870a28cfbd1657d4922c0fafc634a62ebd (diff) | |
virtio: event index interface
Define a new feature bit for the guest and host to utilize
an event index (like Xen) instead if a flag bit to enable/disable
interrupts and kicks.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
| -rw-r--r-- | include/linux/virtio_ring.h | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index a813e5d460eb..c4eef73deb3f 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -52,6 +52,12 @@ /* We support indirect buffer descriptors */ #define VIRTIO_RING_F_INDIRECT_DESC 28 +/* The Guest publishes the used index for which it expects an interrupt + * at the end of the avail ring. Host should ignore the avail->flags field. */ +/* The Host publishes the avail index for which it expects a kick + * at the end of the used ring. Guest should ignore the used->flags field. */ +#define VIRTIO_RING_F_EVENT_IDX 29 + /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ struct vring_desc { /* Address (guest-physical). */ @@ -106,6 +112,7 @@ struct vring { * __u16 avail_flags; * __u16 avail_idx; * __u16 available[num]; + * __u16 used_event_idx; * * // Padding to the next align boundary. * char pad[]; @@ -114,8 +121,14 @@ struct vring { * __u16 used_flags; * __u16 used_idx; * struct vring_used_elem used[num]; + * __u16 avail_event_idx; * }; */ +/* We publish the used event index at the end of the available ring, and vice + * versa. They are at the end for backwards compatibility. */ +#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num]) +#define vring_avail_event(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num]) + static inline void vring_init(struct vring *vr, unsigned int num, void *p, unsigned long align) { @@ -130,7 +143,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) { return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) + align - 1) & ~(align - 1)) - + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num; + + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num; } #ifdef __KERNEL__ |