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virtio_ccw: pass a cookie value to kvm hypercall 

Lookups by channel/vq pair on host during virtio notifications might be
expensive.  Interpret hypercall return value as a cookie which host can
use to do device lookups for the next notification more efficiently.

[CH: Fix line > 80 chars]
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2013-02-28 12:33:16 +01:00 committed by Marcelo Tosatti
parent 503cd0c50a
commit 07e169335f
1 changed files with 8 additions and 3 deletions
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11
drivers/s390/kvm/virtio_ccw.c
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@ -77,6 +77,7 @@ struct virtio_ccw_vq_info {
void *queue;
struct vq_info_block *info_block;
struct list_head node;
long cookie;
};
#define KVM_VIRTIO_CCW_RING_ALIGN 4096
@ -145,15 +146,18 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev,
}
static inline long do_kvm_notify(struct subchannel_id schid,
unsigned long queue_index)
unsigned long queue_index,
long cookie)
{
register unsigned long __nr asm("1") = KVM_S390_VIRTIO_CCW_NOTIFY;
register struct subchannel_id __schid asm("2") = schid;
register unsigned long __index asm("3") = queue_index;
register long __rc asm("2");
register long __cookie asm("4") = cookie;
asm volatile ("diag 2,4,0x500\n"
: "=d" (__rc) : "d" (__nr), "d" (__schid), "d" (__index)
: "=d" (__rc) : "d" (__nr), "d" (__schid), "d" (__index),
"d"(__cookie)
: "memory", "cc");
return __rc;
}
@ -166,7 +170,8 @@ static void virtio_ccw_kvm_notify(struct virtqueue *vq)
vcdev = to_vc_device(info->vq->vdev);
ccw_device_get_schid(vcdev->cdev, &schid);
do_kvm_notify(schid, virtqueue_get_queue_index(vq));
info->cookie = do_kvm_notify(schid, virtqueue_get_queue_index(vq),
info->cookie);
}
static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,