[libvirt] [PATCH v4 9/9] docs: Add vhost-scsi

Eric Farman farman at linux.vnet.ibm.com
Thu Dec 8 14:44:22 UTC 2016

On 12/07/2016 08:16 PM, Jim Fehlig wrote:
> On 11/22/2016 02:16 PM, John Ferlan wrote:
>> On 11/21/2016 10:58 PM, Eric Farman wrote:
>>> Signed-off-by: Eric Farman <farman at linux.vnet.ibm.com>
>>> ---
>>>  docs/formatdomain.html.in | 24 ++++++++++++++++++++++++
>>>  1 file changed, 24 insertions(+)
>> This will get squashed in with the conf patch. I'll also generate the
>> news.html.in entry:
>>           <li>vhost-scsi: Add support scsi_host hostdev passthrough<br/>
>>           Add the capability to pass through a scsi_host HBA and the
>>           associated LUNs to the guest.
>>           </li>
>> ACK -
>> I'll push these in a bit, just seeing what I get on my test system... Of
>> course I'm also curious what would happen if I try to pass through a
>> vHBA ;-)...
> I have unsuccessfully tried it, but not sure how to correctly specify 
> the vHBA in domXML.
> First, create a vHBA:
> cat vhba.xml
> <device>
>    <parent_wwpn>2100001b32847342</parent_wwpn>
>    <parent_wwnn>2000001b32847342</parent_wwnn>
>    <capability type='scsi_host'>
>      <capability type='fc_host'>
>       <wwnn>9990100000000001</wwnn>
>       <wwpn>9990000000000001</wwpn>
>       </capability>
>    </capability>
> </device>
> virsh nodedev-create vhba.xml
> (@John: Notice I'm using your "Allow creation of vHBA by 
> parent_wwnn/wwpn or fabric_name" series. I'll try to respond with 
> review comments on that series tomorrow.)

(@John:  Me too :)

> Add the vHBA to domain config using a variant of Eric's example:
>   <hostdev mode='subsystem' type='scsi_host'>
>     <source protocol='vhost' wwpn='naa.9990000000000001'/>
>     <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x1000'/>
>   </hostdev>
> Start the VM:
> virsh start test
> error: Failed to start domain test
> error: Path '/sys/kernel/config/target/vhost//naa.5001405df3e54061' is 
> not accessible: No such file or directory

Eh?  Where did "5001..." come from?  Given the above hostdev snippet, I 
would've expected this to show "99900..."

Also, if you're not using an s390 machine, the address should probably 
be type='pci' or omitted altogether.

> It looks like this patch series only handles scsi_host created with 
> targetcli, but I didn't look at all the patches closely. 

Today, yes.  But more specifically, it's only handling scsi_host that 
connects to the vhost_scsi target, thus the 
"/sys/kernel/config/target/vhost/" prefix.  The NPIV vport is at a 
different locale.

> Is it possible to use vhost-scsi with NPIV vport (vHBA)? If so, any 
> pointers on how to specify the vHBA in <hostdev> element?

This vhost-scsi series had to do some trickery rather than relying on 
virsh nodedev-list for data.  Looking at John's series, I suspect 
there's some additional work necessary for the vport-capable sysfs 
entries than what exists with this series.  Some of which I deferred 
from an earlier review comment.

  - Eric

> Regards,
> Jim

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