RE: [PATCH v7 06/18] vdpa/ifc: add block device SW live-migration

["Pei, Andy" <andy.pei@intel.com>]

Hi Chenbo,

Thanks for your reply.
Your suggestion is good. I will fix in next version.

> -----Original Message-----
> From: Xia, Chenbo <chenbo.xia@intel.com>
> Sent: Thursday, May 12, 2022 8:55 PM
> To: Pei, Andy <andy.pei@intel.com>; dev@dpdk.org
> Cc: maxime.coquelin@redhat.com; Cao, Gang <gang.cao@intel.com>; Liu,
> Changpeng <changpeng.liu@intel.com>
> Subject: RE: [PATCH v7 06/18] vdpa/ifc: add block device SW live-migration
> 
> > -----Original Message-----
> > From: Pei, Andy <andy.pei@intel.com>
> > Sent: Wednesday, April 27, 2022 4:30 PM
> > To: dev@dpdk.org
> > Cc: Xia, Chenbo <chenbo.xia@intel.com>; maxime.coquelin@redhat.com;
> > Cao, Gang <gang.cao@intel.com>; Liu, Changpeng
> > <changpeng.liu@intel.com>
> > Subject: [PATCH v7 06/18] vdpa/ifc: add block device SW live-migration
> >
> > Add SW live-migration support to block device.
> >
> > Signed-off-by: Andy Pei <andy.pei@intel.com>
> > ---
> >  drivers/vdpa/ifc/ifcvf_vdpa.c | 33 +++++++++++++++++++++++++++++----
> >  1 file changed, 29 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/vdpa/ifc/ifcvf_vdpa.c
> > b/drivers/vdpa/ifc/ifcvf_vdpa.c index 07fc3ca..8a260b7 100644
> > --- a/drivers/vdpa/ifc/ifcvf_vdpa.c
> > +++ b/drivers/vdpa/ifc/ifcvf_vdpa.c
> > @@ -312,6 +312,7 @@ struct rte_vdpa_dev_info {  vdpa_ifcvf_stop(struct
> > ifcvf_internal *internal)  {
> >  	struct ifcvf_hw *hw = &internal->hw;
> > +	struct rte_vhost_vring vq;
> >  	uint32_t i;
> >  	int vid;
> >  	uint64_t features = 0;
> > @@ -319,6 +320,22 @@ struct rte_vdpa_dev_info {
> >  	uint64_t len;
> >
> >  	vid = internal->vid;
> > +
> > +	/* to make sure no packet is lost for blk device
> > +	 * do not stop until last_avail_idx == last_used_idx
> > +	 */
> > +	if (internal->device_type == IFCVF_BLK) {
> > +		for (i = 0; i < hw->nr_vring; i++) {
> > +			rte_vhost_get_vhost_vring(internal->vid, i, &vq);
> > +			while (vq.avail->idx != vq.used->idx) {
> > +				ifcvf_notify_queue(hw, i);
> > +				usleep(10);
> > +			}
> > +			hw->vring[i].last_avail_idx = vq.avail->idx;
> > +			hw->vring[i].last_used_idx = vq.used->idx;
> > +		}
> > +	}
> > +
> 
> This seems not match with the above comment about avoiding in-flight
> packets.
> But the change in patch 17 seems good. Why not just using the
> implementation in patch 17?
> 
> Thanks,
> Chenbo
> 
> >  	ifcvf_stop_hw(hw);
> >
> >  	for (i = 0; i < hw->nr_vring; i++)
> > @@ -642,8 +659,10 @@ struct rte_vdpa_dev_info {
> >  		}
> >  		hw->vring[i].avail = gpa;
> >
> > -		/* Direct I/O for Tx queue, relay for Rx queue */
> > -		if (i & 1) {
> > +		/* NET: Direct I/O for Tx queue, relay for Rx queue
> > +		 * BLK: relay every queue
> > +		 */
> > +		if ((internal->device_type == IFCVF_NET) && (i & 1)) {
> >  			gpa = hva_to_gpa(vid, (uint64_t)(uintptr_t)vq.used);
> >  			if (gpa == 0) {
> >  				DRV_LOG(ERR, "Fail to get GPA for used
> ring."); @@ -693,8 +712,12
> > @@ struct rte_vdpa_dev_info {
> >
> >  	for (i = 0; i < hw->nr_vring; i++) {
> >  		/* synchronize remaining new used entries if any */
> > -		if ((i & 1) == 0)
> > +		if (internal->device_type == IFCVF_NET) {
> > +			if ((i & 1) == 0)
> > +				update_used_ring(internal, i);
> > +		} else if (internal->device_type == IFCVF_BLK) {
> >  			update_used_ring(internal, i);
> > +		}
> >
> >  		rte_vhost_get_vhost_vring(vid, i, &vq);
> >  		len = IFCVF_USED_RING_LEN(vq.size); @@ -756,7 +779,9
> @@ struct
> > rte_vdpa_dev_info {
> >  		}
> >  	}
> >
> > -	for (qid = 0; qid < q_num; qid += 2) {
> > +	for (qid = 0; qid < q_num; qid += 1) {
> > +		if ((internal->device_type == IFCVF_NET) && (qid & 1))
> > +			continue;
> >  		ev.events = EPOLLIN | EPOLLPRI;
> >  		/* leave a flag to mark it's for interrupt */
> >  		ev.data.u64 = 1 | qid << 1 |
> > --
> > 1.8.3.1
>