[pve-devel] [RFC qemu-server] avoid setting lun number for drives when pvscsi controller is used

[Stefan Reiter]

On 6/15/21 10:04 AM, Fabian Ebner wrote:
> Am 14.06.21 um 11:15 schrieb Stefan Reiter:
>> On 6/14/21 8:29 AM, Fabian Ebner wrote:
>>> Any feedback for this?
>>>
>>
>> Looks good to me and works as advertised:
>>
>> Reviewed-by: Stefan Reiter <s.reiter at proxmox.com>
>> Tested-by: Stefan Reiter <s.reiter at proxmox.com>
>>
> 
> Thanks for the review!
> 
>> The `$unit = $drive->{index} % maxdev` logic doesn't seem useful here
>> though, I
>> think it's a copy/paste from the IDE/SATA code below (it was already
>> used before
>> this patch). How about this for a cleanup on top:
>>   >
>> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
>> index c00bde1..afd47b5 100644
>> --- a/PVE/QemuServer.pm
>> +++ b/PVE/QemuServer.pm
>> @@ -1424,7 +1424,6 @@ sub print_drivedevice_full {
>>        } elsif ($drive->{interface} eq 'scsi') {
>>
>>        my ($maxdev, $controller, $controller_prefix) =
>> scsihw_infos($conf, $drive);
>> -    my $unit = $drive->{index} % $maxdev;
> 
> 
> Using LSI 53C895A controller and 9 disks I get
> 
>       kvm: -device
> scsi-hd,bus=scsihw1.0,scsi-id=8,drive=drive-scsi8,id=scsi8: bad scsi
> device id: 8
> 
> As long as scsihw_infos returns the correct thing, I don't see a problem
> sticking to the modular arithmetic ;)
> 

Ah yes, the LSI ones get a new controller every 8 drives, and with pvscsi
$maxdev is 256 anyway... alright, ignore this then :)

>>        my $devicetype = 'hd';
>>        my $path = '';
>>        if (drive_is_cdrom($drive)) {
>> @@ -1452,7 +1451,7 @@ sub print_drivedevice_full {
>>        }
>>
>>        if (!$conf->{scsihw} || $conf->{scsihw} =~ m/^lsi/ ||
>> $conf->{scsihw} eq 'pvscsi') {
>> -       $device =
>> "scsi-$devicetype,bus=$controller_prefix$controller.0,scsi-id=$unit";
>> +       $device =
>> "scsi-$devicetype,bus=$controller_prefix$controller.0,scsi-id=$drive->{index}";
>>
>>        } else {
>>           $device =
>> "scsi-$devicetype,bus=$controller_prefix$controller.0,channel=0,scsi-id=0"
>>               .",lun=$drive->{index}";
>>
>>
>>> Am 13.04.21 um 10:24 schrieb Fabian Ebner:
>>>> Reported in the community forum[0].
>>>>
>>>> In QEMU's hw/scsi/vmw_pvscsi.c in the SCSIBusInfo struct, the max_lun
>>>> property
>>>> is set to 0. This means that in our stack, one cannot have multiple
>>>> disks and
>>>> use 'scsihw: pvscsi' currently, as kvm would fail with
>>>>        bad scsi device lun: 1
>>>>
>>>> Instead of increasing the lun number, increase the scsi-id, as we
>>>> already do for
>>>> lsi.* (in hw/scsi/lsi53c895a.c the max_lun property is also 0).
>>>>
>>>> [0]: https://forum.proxmox.com/threads/kvm-bad-scsi-device-lun-1.84318/
>>>>
>>>> Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
>>>> ---
>>>>
>>>> I'm not experienced in this area, so not at all sure if this is the
>>>> proper
>>>> solution/workaround.
>>>>
>>>>     PVE/QemuServer.pm | 2 +-
>>>>     1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
>>>> index fdb2ac9..4ce663b 100644
>>>> --- a/PVE/QemuServer.pm
>>>> +++ b/PVE/QemuServer.pm
>>>> @@ -1451,7 +1451,7 @@ sub print_drivedevice_full {
>>>>             }
>>>>         }
>>>> -    if (!$conf->{scsihw} || ($conf->{scsihw} =~ m/^lsi/)){
>>>> +    if (!$conf->{scsihw} || $conf->{scsihw} =~ m/^lsi/ ||
>>>> $conf->{scsihw} eq 'pvscsi') {
>>>>             $device =
>>>> "scsi-$devicetype,bus=$controller_prefix$controller.0,scsi-id=$unit";
>>>>         } else {
>>>>             $device =
>>>> "scsi-$devicetype,bus=$controller_prefix$controller.0,channel=0,scsi-id=0"
>>>>
>>>>
>>>
>>>
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