Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Wanlong Gao]

On 03/05/2013 05:17 PM, Asias He wrote:
> In commit 365a7150094 ([SCSI] virtio-scsi: hotplug support for
> virtio-scsi), hotplug support is added to virtio-scsi.
> 
> This patch adds hotplug and hotunplug support to tcm_vhost.
> 
> You can create or delate a LUN in targetcli to hotplug or hotplug a LUN

		   s/delate/delete/			   s/hotplug/hotunplug/

> in guest.

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

On Tue, Mar 05, 2013 at 05:31:00PM +0800, Wanlong Gao wrote:
> On 03/05/2013 05:17 PM, Asias He wrote:
> > In commit 365a7150094 ([SCSI] virtio-scsi: hotplug support for
> > virtio-scsi), hotplug support is added to virtio-scsi.
> > 
> > This patch adds hotplug and hotunplug support to tcm_vhost.
> > 
> > You can create or delate a LUN in targetcli to hotplug or hotplug a LUN
> 
> 		   s/delate/delete/			   s/hotplug/hotunplug/

Thanks. Wrote it too fast ;-)

> > in guest.
> 

-- 
Asias

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Michael S. Tsirkin]

On Tue, Mar 05, 2013 at 05:17:07PM +0800, Asias He wrote:
> In commit 365a7150094 ([SCSI] virtio-scsi: hotplug support for
> virtio-scsi), hotplug support is added to virtio-scsi.
> 
> This patch adds hotplug and hotunplug support to tcm_vhost.
> 
> You can create or delate a LUN in targetcli to hotplug or hotplug a LUN
> in guest.
> 
> Signed-off-by: Asias He <asias@redhat.com>
> ---
>  drivers/vhost/tcm_vhost.c | 171 ++++++++++++++++++++++++++++++++++++++++++++--
>  drivers/vhost/tcm_vhost.h |   9 +++
>  2 files changed, 175 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index 9951297..6693695 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -63,6 +63,8 @@ enum {
>  #define VHOST_SCSI_MAX_TARGET	256
>  #define VHOST_SCSI_MAX_VQ	128
>  
> +#define VHOST_SCSI_FEATURES (VHOST_FEATURES | (1ULL << VIRTIO_SCSI_F_HOTPLUG))
> +
>  struct vhost_scsi {
>  	/* Protected by vhost_scsi->dev.mutex */
>  	struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
> @@ -74,6 +76,11 @@ struct vhost_scsi {
>  
>  	struct vhost_work vs_completion_work; /* cmd completion work item */
>  	struct llist_head vs_completion_list; /* cmd completion queue */
> +
> +	struct vhost_work vs_event_work; /* evt injection work item */
> +	struct llist_head vs_event_list; /* evt injection queue */
> +
> +	bool vs_events_dropped;

Documentation pls.
Also - how is this handled during migration?
Don't we need a way for userspace to retrieve this bit?

>  };
>  
>  /* Local pointer to allocated TCM configfs fabric module */
> @@ -341,6 +348,23 @@ static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
>  	return 0;
>  }
>  
> +static void tcm_vhost_free_evt(struct tcm_vhost_evt *evt)
> +{
> +	kfree(evt);
> +}
> +
> +static struct tcm_vhost_evt *tcm_vhost_allocate_evt(u32 event, u32 reason)
> +{
> +	struct tcm_vhost_evt *evt;
> +
> +	evt = kzalloc(sizeof(*evt), GFP_KERNEL);

And if this fails?

> +
> +	evt->event.event = event;
> +	evt->event.reason = reason;
> +
> +	return evt;
> +}
> +
>  static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
>  {
>  	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> @@ -359,6 +383,71 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
>  	kfree(tv_cmd);
>  }
>  
> +static void tcm_vhost_do_evt_work(struct vhost_scsi *vs,
> +		struct virtio_scsi_event *event)
> +{
> +	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
> +	struct virtio_scsi_event __user *eventp;
> +	unsigned out, in;
> +	int head, ret;
> +
> +	if (!vs || !vs->vs_endpoint)
> +		return;
> +
> +	mutex_lock(&vq->mutex);
> +again:
> +	vhost_disable_notify(&vs->dev, vq);
> +	head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
> +			ARRAY_SIZE(vq->iov), &out, &in,
> +			NULL, NULL);
> +	if (head < 0) {
> +		vs->vs_events_dropped = true;
> +		goto out;
> +	}
> +	if (head == vq->num) {
> +		if (vhost_enable_notify(&vs->dev, vq))
> +			goto again;

Could you code this up using loop, without goto please?

> +		vs->vs_events_dropped = true;
> +		goto out;
> +	}
> +
> +	if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {

We should avoid making layout assumptions. Please don't.

> +		vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes\n",
> +				vq->iov[out].iov_len);
> +		goto out;
> +	}
> +
> +	if (vs->vs_events_dropped) {
> +		event->event |= VIRTIO_SCSI_T_EVENTS_MISSED;
> +		vs->vs_events_dropped = false;
> +	}
> +
> +	eventp = vq->iov[out].iov_base;
> +	ret = __copy_to_user(eventp, event, sizeof(*event));
> +	if (!ret)
> +		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
> +	else
> +		pr_err("Faulted on tcm_vhost_send_event\n");

vq_err please, this is guest triggerable.

> +out:
> +	mutex_unlock(&vq->mutex);
> +}
> +
> +static void tcm_vhost_evt_work(struct vhost_work *work)
> +{
> +	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
> +					vs_event_work);
> +	struct tcm_vhost_evt *evt;
> +	struct llist_node *llnode;
> +
> +	llnode = llist_del_all(&vs->vs_event_list);
> +	while (llnode) {
> +		evt = llist_entry(llnode, struct tcm_vhost_evt, list);
> +		llnode = llist_next(llnode);
> +		tcm_vhost_do_evt_work(vs, &evt->event);
> +		tcm_vhost_free_evt(evt);
> +	}
> +}
> +
>  /* Fill in status and signal that we are done processing this command
>   *
>   * This is scheduled in the vhost work queue so we are called with the owner
> @@ -757,9 +846,41 @@ static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
>  	pr_debug("%s: The handling func for control queue.\n", __func__);
>  }
>  
> +static int tcm_vhost_send_evt(struct vhost_scsi *vs, struct tcm_vhost_tpg *tpg,
> +		struct se_lun *lun, u32 event, u32 reason)

Align ) on ( please.

> +{
> +	struct tcm_vhost_evt *evt;
> +
> +	if (!vs->vs_endpoint)
> +		return -EOPNOTSUPP;
> +

Pls add a comment explaining the abive.
Is this dereference safe without any locking?

> +	evt = tcm_vhost_allocate_evt(event, reason);
> +	if (!evt)
> +		return -ENOMEM;

And what happens then? How about we set event missed flag too?

> +
> +	if (tpg && lun) {
> +		evt->event.lun[0] = 0x01;
> +		evt->event.lun[1] = tpg->tport_tpgt & 0xFF;
> +		if (lun->unpacked_lun >= 256)
> +			evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
> +		evt->event.lun[3] = lun->unpacked_lun & 0xFF;

I know it's not your fault but we really should share this code with
virtio scsi. Pls add TODO now.

> +	}
> +
> +	llist_add(&evt->list, &vs->vs_event_list);

This can queue up quite a bit of memory if the handler thread
is delayed, no? Can we limit the # of outstanding events?
Will guest recover from a missed event?

> +	vhost_work_queue(&vs->dev, &vs->vs_event_work);
> +
> +	return 0;
> +}
> +
>  static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
>  {
> -	pr_debug("%s: The handling func for event queue.\n", __func__);
> +	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> +						poll.work);
> +	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
> +
> +	if (vs->vs_events_dropped)
> +		tcm_vhost_send_evt(vs, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
> +
>  }
>  
>  static void vhost_scsi_handle_kick(struct vhost_work *work)
> @@ -815,6 +936,7 @@ static int vhost_scsi_set_endpoint(
>  				return -EEXIST;
>  			}
>  			tv_tpg->tv_tpg_vhost_count++;
> +			tv_tpg->vhost_scsi = vs;
>  			vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
>  			smp_mb__after_atomic_inc();
>  			match = true;
> @@ -875,6 +997,7 @@ static int vhost_scsi_clear_endpoint(
>  			goto err;
>  		}
>  		tv_tpg->tv_tpg_vhost_count--;
> +		tv_tpg->vhost_scsi = NULL;
>  		vs->vs_tpg[target] = NULL;
>  		vs->vs_endpoint = false;
>  	}
> @@ -896,6 +1019,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
>  		return -ENOMEM;
>  
>  	vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
> +	vhost_work_init(&s->vs_event_work, tcm_vhost_evt_work);
>  
>  	s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick;
>  	s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick;
> @@ -941,7 +1065,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
>  
>  static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
>  {
> -	if (features & ~VHOST_FEATURES)
> +	if (features & ~VHOST_SCSI_FEATURES)
>  		return -EOPNOTSUPP;
>  
>  	mutex_lock(&vs->dev.mutex);
> @@ -987,7 +1111,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
>  			return -EFAULT;
>  		return 0;
>  	case VHOST_GET_FEATURES:
> -		features = VHOST_FEATURES;
> +		features = VHOST_SCSI_FEATURES;
>  		if (copy_to_user(featurep, &features, sizeof features))
>  			return -EFAULT;
>  		return 0;
> @@ -1057,6 +1181,40 @@ static char *tcm_vhost_dump_proto_id(struct tcm_vhost_tport *tport)
>  	return "Unknown";
>  }
>  
> +static int tcm_vhost_hotplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
> +{
> +	struct vhost_scsi *vs = tpg->vhost_scsi;
> +	u64 features;
> +
> +	if (!vs)
> +		return -EOPNOTSUPP;
> +
> +	features = vs->dev.acked_features;
> +	if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
> +		return -EOPNOTSUPP;
> +
> +	return tcm_vhost_send_evt(vs, tpg, lun,
> +			VIRTIO_SCSI_T_TRANSPORT_RESET,
> +			VIRTIO_SCSI_EVT_RESET_RESCAN);
> +}
> +
> +static int tcm_vhost_hotunplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
> +{
> +	struct vhost_scsi *vs = tpg->vhost_scsi;
> +	u64 features;
> +
> +	if (!vs)
> +		return -EOPNOTSUPP;
> +

What are we checking for here, and why is it safe to do
outside any lock?

> +	features = vs->dev.acked_features;
> +	if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
> +		return -EOPNOTSUPP;
> +
> +	return tcm_vhost_send_evt(vs, tpg, lun,
> +			VIRTIO_SCSI_T_TRANSPORT_RESET,
> +			VIRTIO_SCSI_EVT_RESET_REMOVED);
> +}
> +
>  static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
>  	struct se_lun *lun)
>  {
> @@ -1067,18 +1225,21 @@ static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
>  	tv_tpg->tv_tpg_port_count++;
>  	mutex_unlock(&tv_tpg->tv_tpg_mutex);
>  
> +	tcm_vhost_hotplug(tv_tpg, lun);
> +
>  	return 0;
>  }
>  
>  static void tcm_vhost_port_unlink(struct se_portal_group *se_tpg,
> -	struct se_lun *se_lun)
> +	struct se_lun *lun)
>  {
>  	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
>  				struct tcm_vhost_tpg, se_tpg);
> -
>  	mutex_lock(&tv_tpg->tv_tpg_mutex);
>  	tv_tpg->tv_tpg_port_count--;
>  	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +
> +	tcm_vhost_hotunplug(tv_tpg, lun);
>  }
>  
>  static struct se_node_acl *tcm_vhost_make_nodeacl(
> diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
> index 1d2ae7a..191a945 100644
> --- a/drivers/vhost/tcm_vhost.h
> +++ b/drivers/vhost/tcm_vhost.h
> @@ -70,6 +70,8 @@ struct tcm_vhost_tpg {
>  	struct tcm_vhost_tport *tport;
>  	/* Returned by tcm_vhost_make_tpg() */
>  	struct se_portal_group se_tpg;
> +	/* Pointer back to struct vhost_scsi*/
> +	void *vhost_scsi;

Does it have to be void? Any why?
What lock protects this field? Please add a comment.

>  };
>  
>  struct tcm_vhost_tport {
> @@ -83,6 +85,13 @@ struct tcm_vhost_tport {
>  	struct se_wwn tport_wwn;
>  };
>  
> +struct tcm_vhost_evt {
> +	/* virtio_scsi event */
> +	struct virtio_scsi_event event;
> +	/* virtio_scsi event list, serviced from vhost worker thread */
> +	struct llist_node list;
> +};
> +
>  /*
>   * As per request from MST, keep TCM_VHOST related ioctl defines out of
>   * linux/vhost.h (user-space) for now..
> -- 
> 1.8.1.4

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Paolo Bonzini]

Il 05/03/2013 13:11, Michael S. Tsirkin ha scritto:
>> > +
>> > +	struct vhost_work vs_event_work; /* evt injection work item */
>> > +	struct llist_head vs_event_list; /* evt injection queue */
>> > +
>> > +	bool vs_events_dropped;
> Documentation pls.
> Also - how is this handled during migration?

Migration is not supported by vhost-scsi but yes, we would need to
retrieve this bit.

Paolo

> Don't we need a way for userspace to retrieve this bit?
> 

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Michael S. Tsirkin]

On Tue, Mar 05, 2013 at 02:21:20PM +0100, Paolo Bonzini wrote:
> Il 05/03/2013 13:11, Michael S. Tsirkin ha scritto:
> >> > +
> >> > +	struct vhost_work vs_event_work; /* evt injection work item */
> >> > +	struct llist_head vs_event_list; /* evt injection queue */
> >> > +
> >> > +	bool vs_events_dropped;
> > Documentation pls.
> > Also - how is this handled during migration?
> 
> Migration is not supported by vhost-scsi but yes, we would need to
> retrieve this bit.
> 
> Paolo

Well at the moment nothing is supported as there's no userspace
upstream :(

> > Don't we need a way for userspace to retrieve this bit?
> > 

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Nicholas A. Bellinger]

On Tue, 2013-03-05 at 16:34 +0200, Michael S. Tsirkin wrote:
> On Tue, Mar 05, 2013 at 02:21:20PM +0100, Paolo Bonzini wrote:
> > Il 05/03/2013 13:11, Michael S. Tsirkin ha scritto:
> > >> > +
> > >> > +	struct vhost_work vs_event_work; /* evt injection work item */
> > >> > +	struct llist_head vs_event_list; /* evt injection queue */
> > >> > +
> > >> > +	bool vs_events_dropped;
> > > Documentation pls.
> > > Also - how is this handled during migration?
> > 
> > Migration is not supported by vhost-scsi but yes, we would need to
> > retrieve this bit.
> > 
> > Paolo
> 
> Well at the moment nothing is supported as there's no userspace
> upstream :(
> 
> > > Don't we need a way for userspace to retrieve this bit?
> > > 

Btw, the vhost-scsi userspace with ABIv1 bumped for Asias's v3.9
tcm_vhost multi-target kernel changes are here:

http://git.kernel.org/cgit/virt/kvm/nab/qemu-kvm.git/log/?h=vhost-scsi-for-1.3-abi-v1

For making progress with Paolo's vhost-scsi branch on my side, this was
still being blocked by bios boot hangs:

http://www.spinics.net/lists/target-devel/msg03830.html

Paolo & Co, any ideas on the latter..?

--nab

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

On Tue, Mar 05, 2013 at 04:34:17PM +0200, Michael S. Tsirkin wrote:
> On Tue, Mar 05, 2013 at 02:21:20PM +0100, Paolo Bonzini wrote:
> > Il 05/03/2013 13:11, Michael S. Tsirkin ha scritto:
> > >> > +
> > >> > +	struct vhost_work vs_event_work; /* evt injection work item */
> > >> > +	struct llist_head vs_event_list; /* evt injection queue */
> > >> > +
> > >> > +	bool vs_events_dropped;
> > > Documentation pls.
> > > Also - how is this handled during migration?
> > 
> > Migration is not supported by vhost-scsi but yes, we would need to
> > retrieve this bit.
> > 
> > Paolo
> 
> Well at the moment nothing is supported as there's no userspace
> upstream :

This was true if you think only qemu is supposed to support it and
nothing else will use it. kvm tool is using it since last Aug.

> > > Don't we need a way for userspace to retrieve this bit?
> > > 

-- 
Asias

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Paolo Bonzini]

Il 05/03/2013 23:51, Nicholas A. Bellinger ha scritto:
> For making progress with Paolo's vhost-scsi branch on my side, this was
> still being blocked by bios boot hangs:
> 
> http://www.spinics.net/lists/target-devel/msg03830.html
> 
> Paolo & Co, any ideas on the latter..?

Nope.  Asias, do you have time to look at it?  Only patches 3 and 4 in
that series are needed, they are at

http://article.gmane.org/gmane.comp.emulators.qemu/192143
http://article.gmane.org/gmane.comp.emulators.qemu/192147

(vhost_scsi_set_endpoint and vhost_scsi_clear_endpoint need to be
integrated in vhost_scsi_start and vhost_scsi_stop).

Paolo

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

On Wed, Mar 06, 2013 at 03:28:00PM +0100, Paolo Bonzini wrote:
> Il 05/03/2013 23:51, Nicholas A. Bellinger ha scritto:
> > For making progress with Paolo's vhost-scsi branch on my side, this was
> > still being blocked by bios boot hangs:
> > 
> > http://www.spinics.net/lists/target-devel/msg03830.html
> > 
> > Paolo & Co, any ideas on the latter..?
> 
> Nope.  Asias, do you have time to look at it?  Only patches 3 and 4 in
> that series are needed, they are at
> 
> http://article.gmane.org/gmane.comp.emulators.qemu/192143
> http://article.gmane.org/gmane.comp.emulators.qemu/192147
> 
> (vhost_scsi_set_endpoint and vhost_scsi_clear_endpoint need to be
> integrated in vhost_scsi_start and vhost_scsi_stop).

Okay. I will take a look. I am CC'ing Dominik Dingel, he might be
interested in.

Nicholas, could you share the code where you left (on top of Paolo's),
so I can start from.

-- 
Asias

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Nicholas A. Bellinger]

On Thu, 2013-03-07 at 08:55 +0800, Asias He wrote:
> On Wed, Mar 06, 2013 at 03:28:00PM +0100, Paolo Bonzini wrote:
> > Il 05/03/2013 23:51, Nicholas A. Bellinger ha scritto:
> > > For making progress with Paolo's vhost-scsi branch on my side, this was
> > > still being blocked by bios boot hangs:
> > > 
> > > http://www.spinics.net/lists/target-devel/msg03830.html
> > > 
> > > Paolo & Co, any ideas on the latter..?
> > 
> > Nope.  Asias, do you have time to look at it?  Only patches 3 and 4 in
> > that series are needed, they are at
> > 
> > http://article.gmane.org/gmane.comp.emulators.qemu/192143
> > http://article.gmane.org/gmane.comp.emulators.qemu/192147
> > 
> > (vhost_scsi_set_endpoint and vhost_scsi_clear_endpoint need to be
> > integrated in vhost_scsi_start and vhost_scsi_stop).
> 
> Okay. I will take a look. I am CC'ing Dominik Dingel, he might be
> interested in.
> 
> Nicholas, could you share the code where you left (on top of Paolo's),
> so I can start from.
> 

Sure.  Pushing this code to k.o qemu-kvm.git/vhost-scsi-paolo, with the
extra local patches:

vhost-scsi/virtio-scsi: Add backend guest masking support
vhost-scsi: Bump ABI_VERSION to 1

Thanks!

--nab

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

On Thu, Mar 07, 2013 at 02:45:48PM -0800, Nicholas A. Bellinger wrote:
> On Thu, 2013-03-07 at 08:55 +0800, Asias He wrote:
> > On Wed, Mar 06, 2013 at 03:28:00PM +0100, Paolo Bonzini wrote:
> > > Il 05/03/2013 23:51, Nicholas A. Bellinger ha scritto:
> > > > For making progress with Paolo's vhost-scsi branch on my side, this was
> > > > still being blocked by bios boot hangs:
> > > > 
> > > > http://www.spinics.net/lists/target-devel/msg03830.html
> > > > 
> > > > Paolo & Co, any ideas on the latter..?
> > > 
> > > Nope.  Asias, do you have time to look at it?  Only patches 3 and 4 in
> > > that series are needed, they are at
> > > 
> > > http://article.gmane.org/gmane.comp.emulators.qemu/192143
> > > http://article.gmane.org/gmane.comp.emulators.qemu/192147
> > > 
> > > (vhost_scsi_set_endpoint and vhost_scsi_clear_endpoint need to be
> > > integrated in vhost_scsi_start and vhost_scsi_stop).
> > 
> > Okay. I will take a look. I am CC'ing Dominik Dingel, he might be
> > interested in.
> > 
> > Nicholas, could you share the code where you left (on top of Paolo's),
> > so I can start from.
> > 
> 
> Sure.  Pushing this code to k.o qemu-kvm.git/vhost-scsi-paolo, with the
> extra local patches:
> 
> vhost-scsi/virtio-scsi: Add backend guest masking support
> vhost-scsi: Bump ABI_VERSION to 1

Thanks.

-- 
Asias

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

On Tue, Mar 05, 2013 at 02:11:25PM +0200, Michael S. Tsirkin wrote:
> On Tue, Mar 05, 2013 at 05:17:07PM +0800, Asias He wrote:
> > In commit 365a7150094 ([SCSI] virtio-scsi: hotplug support for
> > virtio-scsi), hotplug support is added to virtio-scsi.
> > 
> > This patch adds hotplug and hotunplug support to tcm_vhost.
> > 
> > You can create or delate a LUN in targetcli to hotplug or hotplug a LUN
> > in guest.
> > 
> > Signed-off-by: Asias He <asias@redhat.com>
> > ---
> >  drivers/vhost/tcm_vhost.c | 171 ++++++++++++++++++++++++++++++++++++++++++++--
> >  drivers/vhost/tcm_vhost.h |   9 +++
> >  2 files changed, 175 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> > index 9951297..6693695 100644
> > --- a/drivers/vhost/tcm_vhost.c
> > +++ b/drivers/vhost/tcm_vhost.c
> > @@ -63,6 +63,8 @@ enum {
> >  #define VHOST_SCSI_MAX_TARGET	256
> >  #define VHOST_SCSI_MAX_VQ	128
> >  
> > +#define VHOST_SCSI_FEATURES (VHOST_FEATURES | (1ULL << VIRTIO_SCSI_F_HOTPLUG))
> > +
> >  struct vhost_scsi {
> >  	/* Protected by vhost_scsi->dev.mutex */
> >  	struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
> > @@ -74,6 +76,11 @@ struct vhost_scsi {
> >  
> >  	struct vhost_work vs_completion_work; /* cmd completion work item */
> >  	struct llist_head vs_completion_list; /* cmd completion queue */
> > +
> > +	struct vhost_work vs_event_work; /* evt injection work item */
> > +	struct llist_head vs_event_list; /* evt injection queue */
> > +
> > +	bool vs_events_dropped;
> 
> Documentation pls.
> Also - how is this handled during migration?
> Don't we need a way for userspace to retrieve this bit?

Yes, but migration is not supported atm.

> >  };
> >  
> >  /* Local pointer to allocated TCM configfs fabric module */
> > @@ -341,6 +348,23 @@ static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
> >  	return 0;
> >  }
> >  
> > +static void tcm_vhost_free_evt(struct tcm_vhost_evt *evt)
> > +{
> > +	kfree(evt);
> > +}
> > +
> > +static struct tcm_vhost_evt *tcm_vhost_allocate_evt(u32 event, u32 reason)
> > +{
> > +	struct tcm_vhost_evt *evt;
> > +
> > +	evt = kzalloc(sizeof(*evt), GFP_KERNEL);
> 
> And if this fails?

The check was dropped when I moving around the allocate helper. Will add it back.

> > +
> > +	evt->event.event = event;
> > +	evt->event.reason = reason;
> > +
> > +	return evt;
> > +}
> > +
> >  static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> >  {
> >  	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> > @@ -359,6 +383,71 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> >  	kfree(tv_cmd);
> >  }
> >  
> > +static void tcm_vhost_do_evt_work(struct vhost_scsi *vs,
> > +		struct virtio_scsi_event *event)
> > +{
> > +	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
> > +	struct virtio_scsi_event __user *eventp;
> > +	unsigned out, in;
> > +	int head, ret;
> > +
> > +	if (!vs || !vs->vs_endpoint)
> > +		return;
> > +
> > +	mutex_lock(&vq->mutex);
> > +again:
> > +	vhost_disable_notify(&vs->dev, vq);
> > +	head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
> > +			ARRAY_SIZE(vq->iov), &out, &in,
> > +			NULL, NULL);
> > +	if (head < 0) {
> > +		vs->vs_events_dropped = true;
> > +		goto out;
> > +	}
> > +	if (head == vq->num) {
> > +		if (vhost_enable_notify(&vs->dev, vq))
> > +			goto again;
> 
> Could you code this up using loop, without goto please?

This is not a loop actaully. We only need to grap one buffer at a time.
IMHO, It is even uglier to user a loop: 1) you need to exit the loop
arbitary at the end. 2) Extra indention.

> > +		vs->vs_events_dropped = true;
> > +		goto out;
> > +	}
> > +
> > +	if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {
> 
> We should avoid making layout assumptions. Please don't.

Other places is doing this as well, e.g vhost_scsi_handle_vq(). Will do
the conversion to no layout assumptions mode in further patches to
convert all of them.

> > +		vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes\n",
> > +				vq->iov[out].iov_len);
> > +		goto out;
> > +	}
> > +
> > +	if (vs->vs_events_dropped) {
> > +		event->event |= VIRTIO_SCSI_T_EVENTS_MISSED;
> > +		vs->vs_events_dropped = false;
> > +	}
> > +
> > +	eventp = vq->iov[out].iov_base;
> > +	ret = __copy_to_user(eventp, event, sizeof(*event));
> > +	if (!ret)
> > +		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
> > +	else
> > +		pr_err("Faulted on tcm_vhost_send_event\n");
> 
> vq_err please, this is guest triggerable.

Okay. Will fix other places too.

> > +out:
> > +	mutex_unlock(&vq->mutex);
> > +}
> > +
> > +static void tcm_vhost_evt_work(struct vhost_work *work)
> > +{
> > +	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
> > +					vs_event_work);
> > +	struct tcm_vhost_evt *evt;
> > +	struct llist_node *llnode;
> > +
> > +	llnode = llist_del_all(&vs->vs_event_list);
> > +	while (llnode) {
> > +		evt = llist_entry(llnode, struct tcm_vhost_evt, list);
> > +		llnode = llist_next(llnode);
> > +		tcm_vhost_do_evt_work(vs, &evt->event);
> > +		tcm_vhost_free_evt(evt);
> > +	}
> > +}
> > +
> >  /* Fill in status and signal that we are done processing this command
> >   *
> >   * This is scheduled in the vhost work queue so we are called with the owner
> > @@ -757,9 +846,41 @@ static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
> >  	pr_debug("%s: The handling func for control queue.\n", __func__);
> >  }
> >  
> > +static int tcm_vhost_send_evt(struct vhost_scsi *vs, struct tcm_vhost_tpg *tpg,
> > +		struct se_lun *lun, u32 event, u32 reason)
> 
> Align ) on ( please.

What is the preferred alignment here? Can you elaborate?

> > +{
> > +	struct tcm_vhost_evt *evt;
> > +
> > +	if (!vs->vs_endpoint)
> > +		return -EOPNOTSUPP;
> > +
> 
> Pls add a comment explaining the abive.
> Is this dereference safe without any locking?

vs->vs_endpoint is protected by vhost_scsi->dev.mutex. It is ok to use
the lock for event vq. But for the cmd vq, it is not optimal to take the
lock in the data path. We have this in 
   vhost_scsi_handle_vq ()
   {
   	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
   	if (unlikely(!vs->vs_endpoint))
   		return;
   }

> > +	evt = tcm_vhost_allocate_evt(event, reason);
> > +	if (!evt)
> > +		return -ENOMEM;
> 
> And what happens then? How about we set event missed flag too?

Okay.

> > +
> > +	if (tpg && lun) {
> > +		evt->event.lun[0] = 0x01;
> > +		evt->event.lun[1] = tpg->tport_tpgt & 0xFF;
> > +		if (lun->unpacked_lun >= 256)
> > +			evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
> > +		evt->event.lun[3] = lun->unpacked_lun & 0xFF;
> 
> I know it's not your fault but we really should share this code with
> virtio scsi. Pls add TODO now.

Ok.

> > +	}
> > +
> > +	llist_add(&evt->list, &vs->vs_event_list);
> 
> This can queue up quite a bit of memory if the handler thread
> is delayed, no? Can we limit the # of outstanding events?
> Will guest recover from a missed event?

Hmm, good point. Will limit the number. The size of 'struct
tcm_vhost_evt' is around 20 bytes. So if we limit it to 128, it is ~2.5K
of memory.

Paolo, if we limit the number of outstanding events and set
vs->vs_events_dropped, the guest will recover from a missed event, right?

> > +	vhost_work_queue(&vs->dev, &vs->vs_event_work);
> > +
> > +	return 0;
> > +}
> > +
> >  static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
> >  {
> > -	pr_debug("%s: The handling func for event queue.\n", __func__);
> > +	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> > +						poll.work);
> > +	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
> > +
> > +	if (vs->vs_events_dropped)
> > +		tcm_vhost_send_evt(vs, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
> > +
> >  }
> >  
> >  static void vhost_scsi_handle_kick(struct vhost_work *work)
> > @@ -815,6 +936,7 @@ static int vhost_scsi_set_endpoint(
> >  				return -EEXIST;
> >  			}
> >  			tv_tpg->tv_tpg_vhost_count++;
> > +			tv_tpg->vhost_scsi = vs;
> >  			vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
> >  			smp_mb__after_atomic_inc();
> >  			match = true;
> > @@ -875,6 +997,7 @@ static int vhost_scsi_clear_endpoint(
> >  			goto err;
> >  		}
> >  		tv_tpg->tv_tpg_vhost_count--;
> > +		tv_tpg->vhost_scsi = NULL;
> >  		vs->vs_tpg[target] = NULL;
> >  		vs->vs_endpoint = false;
> >  	}
> > @@ -896,6 +1019,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
> >  		return -ENOMEM;
> >  
> >  	vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
> > +	vhost_work_init(&s->vs_event_work, tcm_vhost_evt_work);
> >  
> >  	s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick;
> >  	s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick;
> > @@ -941,7 +1065,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
> >  
> >  static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> >  {
> > -	if (features & ~VHOST_FEATURES)
> > +	if (features & ~VHOST_SCSI_FEATURES)
> >  		return -EOPNOTSUPP;
> >  
> >  	mutex_lock(&vs->dev.mutex);
> > @@ -987,7 +1111,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
> >  			return -EFAULT;
> >  		return 0;
> >  	case VHOST_GET_FEATURES:
> > -		features = VHOST_FEATURES;
> > +		features = VHOST_SCSI_FEATURES;
> >  		if (copy_to_user(featurep, &features, sizeof features))
> >  			return -EFAULT;
> >  		return 0;
> > @@ -1057,6 +1181,40 @@ static char *tcm_vhost_dump_proto_id(struct tcm_vhost_tport *tport)
> >  	return "Unknown";
> >  }
> >  
> > +static int tcm_vhost_hotplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
> > +{
> > +	struct vhost_scsi *vs = tpg->vhost_scsi;
> > +	u64 features;
> > +
> > +	if (!vs)
> > +		return -EOPNOTSUPP;
> > +
> > +	features = vs->dev.acked_features;
> > +	if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
> > +		return -EOPNOTSUPP;
> > +
> > +	return tcm_vhost_send_evt(vs, tpg, lun,
> > +			VIRTIO_SCSI_T_TRANSPORT_RESET,
> > +			VIRTIO_SCSI_EVT_RESET_RESCAN);
> > +}
> > +
> > +static int tcm_vhost_hotunplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
> > +{
> > +	struct vhost_scsi *vs = tpg->vhost_scsi;
> > +	u64 features;
> > +
> > +	if (!vs)
> > +		return -EOPNOTSUPP;
> > +
> 
> What are we checking for here, and why is it safe to do
> outside any lock?

tcm_vhost_hotplug and tcm_vhost_hotunplug might be called when
vhost-scsi is not opened. Will add the locking.

> > +	features = vs->dev.acked_features;
> > +	if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
> > +		return -EOPNOTSUPP;
> > +
> > +	return tcm_vhost_send_evt(vs, tpg, lun,
> > +			VIRTIO_SCSI_T_TRANSPORT_RESET,
> > +			VIRTIO_SCSI_EVT_RESET_REMOVED);
> > +}
> > +
> >  static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
> >  	struct se_lun *lun)
> >  {
> > @@ -1067,18 +1225,21 @@ static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
> >  	tv_tpg->tv_tpg_port_count++;
> >  	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> >  
> > +	tcm_vhost_hotplug(tv_tpg, lun);
> > +
> >  	return 0;
> >  }
> >  
> >  static void tcm_vhost_port_unlink(struct se_portal_group *se_tpg,
> > -	struct se_lun *se_lun)
> > +	struct se_lun *lun)
> >  {
> >  	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> >  				struct tcm_vhost_tpg, se_tpg);
> > -
> >  	mutex_lock(&tv_tpg->tv_tpg_mutex);
> >  	tv_tpg->tv_tpg_port_count--;
> >  	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> > +
> > +	tcm_vhost_hotunplug(tv_tpg, lun);
> >  }
> >  
> >  static struct se_node_acl *tcm_vhost_make_nodeacl(
> > diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
> > index 1d2ae7a..191a945 100644
> > --- a/drivers/vhost/tcm_vhost.h
> > +++ b/drivers/vhost/tcm_vhost.h
> > @@ -70,6 +70,8 @@ struct tcm_vhost_tpg {
> >  	struct tcm_vhost_tport *tport;
> >  	/* Returned by tcm_vhost_make_tpg() */
> >  	struct se_portal_group se_tpg;
> > +	/* Pointer back to struct vhost_scsi*/
> > +	void *vhost_scsi;
> 
> Does it have to be void? Any why?
> What lock protects this field? Please add a comment.

struct vhost_scsi is defined in tcm_vhost.c.
tv_tpg_mutex will protect it.

Does this look good?

diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
index 191a945..8941a54 100644
--- a/drivers/vhost/tcm_vhost.h
+++ b/drivers/vhost/tcm_vhost.h
@@ -53,6 +53,7 @@ struct tcm_vhost_nacl {
 	struct se_node_acl se_node_acl;
 };
 
+struct vhost_scsi;
 struct tcm_vhost_tpg {
 	/* Vhost port target portal group tag for TCM */
 	u16 tport_tpgt;
@@ -71,7 +72,7 @@ struct tcm_vhost_tpg {
 	/* Returned by tcm_vhost_make_tpg() */
 	struct se_portal_group se_tpg;
 	/* Pointer back to struct vhost_scsi*/
-	void *vhost_scsi;
+	struct vhost_scsi *vhost_scsi;
 };
 
 struct tcm_vhost_tport {


> >  };
> >  
> >  struct tcm_vhost_tport {
> > @@ -83,6 +85,13 @@ struct tcm_vhost_tport {
> >  	struct se_wwn tport_wwn;
> >  };
> >  
> > +struct tcm_vhost_evt {
> > +	/* virtio_scsi event */
> > +	struct virtio_scsi_event event;
> > +	/* virtio_scsi event list, serviced from vhost worker thread */
> > +	struct llist_node list;
> > +};
> > +
> >  /*
> >   * As per request from MST, keep TCM_VHOST related ioctl defines out of
> >   * linux/vhost.h (user-space) for now..
> > -- 
> > 1.8.1.4

-- 
Asias

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Paolo Bonzini]

Il 06/03/2013 02:28, Asias He ha scritto:
>> > This can queue up quite a bit of memory if the handler thread
>> > is delayed, no? Can we limit the # of outstanding events?
>> > Will guest recover from a missed event?
> Hmm, good point. Will limit the number. The size of 'struct
> tcm_vhost_evt' is around 20 bytes. So if we limit it to 128, it is ~2.5K
> of memory.
> 
> Paolo, if we limit the number of outstanding events and set
> vs->vs_events_dropped, the guest will recover from a missed event, right?

Yes.  At least it should (it doesn't yet).

Paolo

Re: [PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

On Wed, Mar 06, 2013 at 06:41:47PM +0100, Paolo Bonzini wrote:
> Il 06/03/2013 02:28, Asias He ha scritto:
> >> > This can queue up quite a bit of memory if the handler thread
> >> > is delayed, no? Can we limit the # of outstanding events?
> >> > Will guest recover from a missed event?
> > Hmm, good point. Will limit the number. The size of 'struct
> > tcm_vhost_evt' is around 20 bytes. So if we limit it to 128, it is ~2.5K
> > of memory.
> > 
> > Paolo, if we limit the number of outstanding events and set
> > vs->vs_events_dropped, the guest will recover from a missed event, right?
> 
> Yes.  At least it should (it doesn't yet).

Ok, thanks.

> Paolo
> 

-- 
Asias

[PATCH] tcm_vhost: Add hotplug/hotunplug support

[Asias He]

In commit 365a7150094 ([SCSI] virtio-scsi: hotplug support for
virtio-scsi), hotplug support is added to virtio-scsi.

This patch adds hotplug and hotunplug support to tcm_vhost.

You can create or delate a LUN in targetcli to hotplug or hotplug a LUN
in guest.

Signed-off-by: Asias He <asias@redhat.com>
---
 drivers/vhost/tcm_vhost.c | 171 ++++++++++++++++++++++++++++++++++++++++++++--
 drivers/vhost/tcm_vhost.h |   9 +++
 2 files changed, 175 insertions(+), 5 deletions(-)

diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
index 9951297..6693695 100644
--- a/drivers/vhost/tcm_vhost.c
+++ b/drivers/vhost/tcm_vhost.c
@@ -63,6 +63,8 @@ enum {
 #define VHOST_SCSI_MAX_TARGET	256
 #define VHOST_SCSI_MAX_VQ	128
 
+#define VHOST_SCSI_FEATURES (VHOST_FEATURES | (1ULL << VIRTIO_SCSI_F_HOTPLUG))
+
 struct vhost_scsi {
 	/* Protected by vhost_scsi->dev.mutex */
 	struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
@@ -74,6 +76,11 @@ struct vhost_scsi {
 
 	struct vhost_work vs_completion_work; /* cmd completion work item */
 	struct llist_head vs_completion_list; /* cmd completion queue */
+
+	struct vhost_work vs_event_work; /* evt injection work item */
+	struct llist_head vs_event_list; /* evt injection queue */
+
+	bool vs_events_dropped;
 };
 
 /* Local pointer to allocated TCM configfs fabric module */
@@ -341,6 +348,23 @@ static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
 	return 0;
 }
 
+static void tcm_vhost_free_evt(struct tcm_vhost_evt *evt)
+{
+	kfree(evt);
+}
+
+static struct tcm_vhost_evt *tcm_vhost_allocate_evt(u32 event, u32 reason)
+{
+	struct tcm_vhost_evt *evt;
+
+	evt = kzalloc(sizeof(*evt), GFP_KERNEL);
+
+	evt->event.event = event;
+	evt->event.reason = reason;
+
+	return evt;
+}
+
 static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
 {
 	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
@@ -359,6 +383,71 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
 	kfree(tv_cmd);
 }
 
+static void tcm_vhost_do_evt_work(struct vhost_scsi *vs,
+		struct virtio_scsi_event *event)
+{
+	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT];
+	struct virtio_scsi_event __user *eventp;
+	unsigned out, in;
+	int head, ret;
+
+	if (!vs || !vs->vs_endpoint)
+		return;
+
+	mutex_lock(&vq->mutex);
+again:
+	vhost_disable_notify(&vs->dev, vq);
+	head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
+			ARRAY_SIZE(vq->iov), &out, &in,
+			NULL, NULL);
+	if (head < 0) {
+		vs->vs_events_dropped = true;
+		goto out;
+	}
+	if (head == vq->num) {
+		if (vhost_enable_notify(&vs->dev, vq))
+			goto again;
+		vs->vs_events_dropped = true;
+		goto out;
+	}
+
+	if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {
+		vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes\n",
+				vq->iov[out].iov_len);
+		goto out;
+	}
+
+	if (vs->vs_events_dropped) {
+		event->event |= VIRTIO_SCSI_T_EVENTS_MISSED;
+		vs->vs_events_dropped = false;
+	}
+
+	eventp = vq->iov[out].iov_base;
+	ret = __copy_to_user(eventp, event, sizeof(*event));
+	if (!ret)
+		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+	else
+		pr_err("Faulted on tcm_vhost_send_event\n");
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static void tcm_vhost_evt_work(struct vhost_work *work)
+{
+	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
+					vs_event_work);
+	struct tcm_vhost_evt *evt;
+	struct llist_node *llnode;
+
+	llnode = llist_del_all(&vs->vs_event_list);
+	while (llnode) {
+		evt = llist_entry(llnode, struct tcm_vhost_evt, list);
+		llnode = llist_next(llnode);
+		tcm_vhost_do_evt_work(vs, &evt->event);
+		tcm_vhost_free_evt(evt);
+	}
+}
+
 /* Fill in status and signal that we are done processing this command
  *
  * This is scheduled in the vhost work queue so we are called with the owner
@@ -757,9 +846,41 @@ static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
 	pr_debug("%s: The handling func for control queue.\n", __func__);
 }
 
+static int tcm_vhost_send_evt(struct vhost_scsi *vs, struct tcm_vhost_tpg *tpg,
+		struct se_lun *lun, u32 event, u32 reason)
+{
+	struct tcm_vhost_evt *evt;
+
+	if (!vs->vs_endpoint)
+		return -EOPNOTSUPP;
+
+	evt = tcm_vhost_allocate_evt(event, reason);
+	if (!evt)
+		return -ENOMEM;
+
+	if (tpg && lun) {
+		evt->event.lun[0] = 0x01;
+		evt->event.lun[1] = tpg->tport_tpgt & 0xFF;
+		if (lun->unpacked_lun >= 256)
+			evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
+		evt->event.lun[3] = lun->unpacked_lun & 0xFF;
+	}
+
+	llist_add(&evt->list, &vs->vs_event_list);
+	vhost_work_queue(&vs->dev, &vs->vs_event_work);
+
+	return 0;
+}
+
 static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
 {
-	pr_debug("%s: The handling func for event queue.\n", __func__);
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						poll.work);
+	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
+
+	if (vs->vs_events_dropped)
+		tcm_vhost_send_evt(vs, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
+
 }
 
 static void vhost_scsi_handle_kick(struct vhost_work *work)
@@ -815,6 +936,7 @@ static int vhost_scsi_set_endpoint(
 				return -EEXIST;
 			}
 			tv_tpg->tv_tpg_vhost_count++;
+			tv_tpg->vhost_scsi = vs;
 			vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
 			smp_mb__after_atomic_inc();
 			match = true;
@@ -875,6 +997,7 @@ static int vhost_scsi_clear_endpoint(
 			goto err;
 		}
 		tv_tpg->tv_tpg_vhost_count--;
+		tv_tpg->vhost_scsi = NULL;
 		vs->vs_tpg[target] = NULL;
 		vs->vs_endpoint = false;
 	}
@@ -896,6 +1019,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 		return -ENOMEM;
 
 	vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
+	vhost_work_init(&s->vs_event_work, tcm_vhost_evt_work);
 
 	s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick;
 	s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick;
@@ -941,7 +1065,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
 
 static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
 {
-	if (features & ~VHOST_FEATURES)
+	if (features & ~VHOST_SCSI_FEATURES)
 		return -EOPNOTSUPP;
 
 	mutex_lock(&vs->dev.mutex);
@@ -987,7 +1111,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
 			return -EFAULT;
 		return 0;
 	case VHOST_GET_FEATURES:
-		features = VHOST_FEATURES;
+		features = VHOST_SCSI_FEATURES;
 		if (copy_to_user(featurep, &features, sizeof features))
 			return -EFAULT;
 		return 0;
@@ -1057,6 +1181,40 @@ static char *tcm_vhost_dump_proto_id(struct tcm_vhost_tport *tport)
 	return "Unknown";
 }
 
+static int tcm_vhost_hotplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
+{
+	struct vhost_scsi *vs = tpg->vhost_scsi;
+	u64 features;
+
+	if (!vs)
+		return -EOPNOTSUPP;
+
+	features = vs->dev.acked_features;
+	if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
+		return -EOPNOTSUPP;
+
+	return tcm_vhost_send_evt(vs, tpg, lun,
+			VIRTIO_SCSI_T_TRANSPORT_RESET,
+			VIRTIO_SCSI_EVT_RESET_RESCAN);
+}
+
+static int tcm_vhost_hotunplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
+{
+	struct vhost_scsi *vs = tpg->vhost_scsi;
+	u64 features;
+
+	if (!vs)
+		return -EOPNOTSUPP;
+
+	features = vs->dev.acked_features;
+	if (!(features & 1ULL << VIRTIO_SCSI_F_HOTPLUG))
+		return -EOPNOTSUPP;
+
+	return tcm_vhost_send_evt(vs, tpg, lun,
+			VIRTIO_SCSI_T_TRANSPORT_RESET,
+			VIRTIO_SCSI_EVT_RESET_REMOVED);
+}
+
 static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
 	struct se_lun *lun)
 {
@@ -1067,18 +1225,21 @@ static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
 	tv_tpg->tv_tpg_port_count++;
 	mutex_unlock(&tv_tpg->tv_tpg_mutex);
 
+	tcm_vhost_hotplug(tv_tpg, lun);
+
 	return 0;
 }
 
 static void tcm_vhost_port_unlink(struct se_portal_group *se_tpg,
-	struct se_lun *se_lun)
+	struct se_lun *lun)
 {
 	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
 				struct tcm_vhost_tpg, se_tpg);
-
 	mutex_lock(&tv_tpg->tv_tpg_mutex);
 	tv_tpg->tv_tpg_port_count--;
 	mutex_unlock(&tv_tpg->tv_tpg_mutex);
+
+	tcm_vhost_hotunplug(tv_tpg, lun);
 }
 
 static struct se_node_acl *tcm_vhost_make_nodeacl(
diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
index 1d2ae7a..191a945 100644
--- a/drivers/vhost/tcm_vhost.h
+++ b/drivers/vhost/tcm_vhost.h
@@ -70,6 +70,8 @@ struct tcm_vhost_tpg {
 	struct tcm_vhost_tport *tport;
 	/* Returned by tcm_vhost_make_tpg() */
 	struct se_portal_group se_tpg;
+	/* Pointer back to struct vhost_scsi*/
+	void *vhost_scsi;
 };
 
 struct tcm_vhost_tport {
@@ -83,6 +85,13 @@ struct tcm_vhost_tport {
 	struct se_wwn tport_wwn;
 };
 
+struct tcm_vhost_evt {
+	/* virtio_scsi event */
+	struct virtio_scsi_event event;
+	/* virtio_scsi event list, serviced from vhost worker thread */
+	struct llist_node list;
+};
+
 /*
  * As per request from MST, keep TCM_VHOST related ioctl defines out of
  * linux/vhost.h (user-space) for now..
-- 
1.8.1.4