Re: pvSCSI test

[Juergen Gross <jgross@suse.com>]

On 02/06/2015 10:32 AM, Kristian Hagsted Rasmussen wrote:
> On Wednesday, February 4, 2015 05:41, Juergen Gross <jgross@suse.com> wrote:
>> To: Kristian Hagsted Rasmussen; Olaf Hering; xen-devel@lists.xensource.com
>> Subject: Re: pvSCSI test
>>
>> On 02/03/2015 07:16 PM, Kristian Hagsted Rasmussen wrote:
>>>
>>> Hi Olaf and Juergen
>>>
>>>
>>> I am interested in testing pvSCSI as I have a system were it would be ideal.
>>> I have tried to apply this patch "http://marc.info/?l=xen-devel&m=139885599019457&w=2" called "libbxl: add support for pvscsi, iteration 1", to my xen-4.5 tree.
>>> I am using kernel 3.18.4 compiled with xen-scsiback and xen-scsifront compiled into the kernel, for both Dom0 and DomU.
>>>
>>>    My Ubuntu domU is running fine, however the scsi disk I want to pass through does not appear.
>>>
>>> in my config I have added the line:
>>> vscsi= ['3:0:0:0,0:0:0:0']
>>> I have also tried with:
>>> vscsi= ['/dev/sdb,0:0:0:0']
>>>
>>> but no matter which syntax I use I get the following error in dmesg log:
>>> xen-pvscsi: 3:0:0:0 doesn't exist
>>>
>>> I have no errors in the log files for the domU.
>>>
>>> Am I missing something in my configuration, perhaps some device hiding like for pci pass through?
>>
>> The upstream pvscsi backend is using the target infrastructure. Until
>> the tools are aware of this you'll have to configure the device to
>> pass to a domain in Dom0 e.g. via a script:
>>
>> #!/bin/bash
>> # usage:
>> # mkpvscsi device
>> # e.g. mkpvscsi /dev/sr0
>>
>> DEV=$1
>>
>> gen_uuid()
>> {
>>           cat /proc/sys/kernel/random/uuid | \
>>          awk '{print "naa.6001405" substr($1,1,8) substr($1,10,1);}'
>> }
>>
>> TARG=`gen_uuid`
>> INIT=`gen_uuid`
>>
>> NODE=`lsscsi | awk '$(NF) == "'$DEV'"
>>          { print substr($1,2,length($1)-4); }'`
>> NAME=`echo $NODE | sed 's/:/_/g'`
>>
>
> I used targetcli to create the pscsi target, so
> skipped from here
>
>> modprobe configfs
>> mount -t configfs configfs /sys/kernel/config
>> modprobe xen-scsiback
>> modprobe target_core_mod
>
> to here
>
>> cd /sys/kernel/config/target
>>
>
> and here to
>
>> mkdir -p core/pscsi_0/$NAME
>> echo "$DEV" >core/pscsi_0/$NAME/udev_path
>>
> to here
>
>> mkdir -p xen-pvscsi/$TARG/tpgt_0
>> echo "$NODE" >xen-pvscsi/$TARG/tpgt_0/param/alias
>> echo $INIT >xen-pvscsi/$TARG/tpgt_0/nexus
>> mkdir xen-pvscsi/$TARG/tpgt_0/lun/lun_0
>>
>> cd xen-pvscsi/$TARG/tpgt_0/lun/lun_0
>> ln -s ../../../../../../target/core/pscsi_0/$NAME xen-pvscsi_port
>>
>>
>>
>> -------------
>>
>> After doing this you can use the xen tools to give the device to a domU.
>> Please note: this script is untested, I've used a simpler one which
>> fitted my needs (using targetcli, which isn't available everywhere).
>> I have tested all single steps of the script above, though.
>
> Thanks for the script, I had some problems with the symlinking when
> running the script, so tried to make the pscsi in targetcli, and then
> shortening the script to skip all script lines concerning the core dir.
> This made the script working for me, however I still get:
> xen-pvscsi: 3:0:0:0 doesn't exist
> error in dmesg log.
>
> Are you using another patch for the xen-tree than the one I listed above?

I've used xm to get the drivers working, not xl. I wanted to have only
one changed component during tests in order to know which component is
failing. :-)

What are the contents of

/sys/kernel/config/target/xen-pvscsi/$TARG/tpgt_0/param/alias

($TARG replaced by the UUID generated above, of course)?

This should be "3:0:0:0" in your case. That's where the backend is
looking for the match from xenstore.

And the final symlink in the script is required. $NAME can be anything,
but has to match the pscsi name, of course.

Juergen