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Commit 07e16933 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Marcelo Tosatti
Browse files

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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 503cd0c5

drivers/s390/kvm/virtio_ccw.c

+8 −3
Original line number Diff line number Diff line
@@ -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,