Define a new feature bit for the guest to utilize a used_event index (like Xen) instead if a flag bit to enable/disable interrupts. Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> --- include/linux/virtio_ring.h | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index e4d144b..f5c1b75 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -29,6 +29,10 @@ /* 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. */ +#define VIRTIO_RING_F_USED_EVENT_IDX 29 + /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ struct vring_desc { /* Address (guest-physical). */ @@ -83,6 +87,7 @@ struct vring { * __u16 avail_flags; * __u16 avail_idx; * __u16 available[num]; + * __u16 used_event_idx; * * // Padding to the next align boundary. * char pad[]; @@ -93,6 +98,10 @@ struct vring { * struct vring_used_elem used[num]; * }; */ +/* We publish the used event index at the end of the available ring. + * It is at the end for backwards compatibility. */ +#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num]) + static inline void vring_init(struct vring *vr, unsigned int num, void *p, unsigned long align) { -- 1.7.5.53.gc233e -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html