Re: [Qemu-devel] [RESEND PATCH] virtio-scsi: forward scsibus for virtio-scsi-pci.

[Frederic Konrad <fred.konrad@greensocs.com>]

On 13/06/2013 09:23, Michael S. Tsirkin wrote:
> On Thu, Jun 13, 2013 at 04:46:09PM +1000, Alexey Kardashevskiy wrote:
>> On 06/13/2013 04:28 PM, Frederic Konrad wrote:
>>> On 12/06/2013 13:21, Alexey Kardashevskiy wrote:
>>>> On 06/12/2013 07:16 PM, Michael S. Tsirkin wrote:
>>>>> On Wed, Jun 12, 2013 at 07:04:48PM +1000, Alexey Kardashevskiy wrote:
>>>>>> On 06/12/2013 07:03 PM, Michael S. Tsirkin wrote:
>>>>>>> On Wed, Jun 12, 2013 at 08:15:17AM +0200, fred.konrad@greensocs.com
>>>>>>> wrote:
>>>>>>>> From: KONRAD Frederic <fred.konrad@greensocs.com>
>>>>>>>>
>>>>>>>> This fix a bug with scsi hotplug on virtio-scsi-pci:
>>>>>>>>
>>>>>>>> As virtio-scsi-pci doesn't have any scsi bus, we need to forward
>>>>>>>> scsi-hot-add
>>>>>>>> to the virtio-scsi-device plugged on the virtio-bus.
>>>>>>>>
>>>>>>>> Cc: qemu-stable@nongnu.org
>>>>>>>> Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>>>>>>> Reviewed-by: Andreas Färber <afaerber@suse.de>
>>>>>>>> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
>>>>>>> Acked-by: Michael S. Tsirkin <mst@redhat.com>
>>>>>>>
>>>>>>> Note: we don't seem to have any decent way to
>>>>>>> add disks to devices: no QMP interface,
>>>>>>> pci address is required instead of using an id ...
>>>>>>>
>>>>>>> Anyone can be bothered to fix this?
>>>>>> Actually PCI address is not always required, this field (we are talking
>>>>>> about "drive_add"?) is ignored when "if=none".
>>>>>>
>>>>> Then documentation in hmp-commands.hx is wrong, isn't it?
>>>>> Add that to the list.
>>>>>
>>>>> if=none can't be actually used to hot-add
>>>>> a disk to a device, can it? It creates a disc and assumes you will
>>>>> use it by a device created later.
>>>> Yep. I run QEMU with -device "virtio-scsi-pci,id=device0" and then do in
>>>> console:
>>>> drive_add auto file=virtimg/fc18guest,if=none,id=bar1
>>>> device_add scsi-disk,bus=device0.0,drive=bar1
>>>>
>>>> Pretty hot plug :)
>>> I thought you use drive_add 0 if=scsi?
>>
>> That's the other option, I posted a bug but I did not actually try the fix
>> till now :)
>>
>> It works now if I run QEMU with "-device virtio-scsi-pci" and do this in
>> qemu console:
>> drive_add 0 file=virtimg/fc18guest
>>
>> No extra parameters or anything, cool, thanks, and :)
>>
>> Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>
>>
>> The only problem with it that it still wants PCI SCSI adapter while
>> spapr-vscsi is VIO device so if the guest kernel does not have virtio-scsi
>> support, I have to do what I described in the quote but this is a different
>> story.
> Okay.  How about:
> - document that pci_addr is optional in hmp
> - if no pci_addr assume if=none
> - add drive_add to qmp without the pci_addr and if options
>
> We are left with the bus=device0.0 syntax for device_add which is also
> gross - user asked for device0, the .0 part is qemu internals exposed to
> users.
> How about teaching qdev that if there's a single bus under a device,
> naming the device itself should be identical?

Yes why not seems a good idea, but you'll pass it through bus= option?
> This will solve the problem neatly without virtio specific hacks,
> won't it?

The issue here is command line back-compatibility for pci_addr, which 
won't be solved with
the "single bus" idea?

>
>>
>>>>
>>>>>>>> ---
>>>>>>>>    hw/pci/pci-hotplug.c | 19 +++++++++++++++++--
>>>>>>>>    1 file changed, 17 insertions(+), 2 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/hw/pci/pci-hotplug.c b/hw/pci/pci-hotplug.c
>>>>>>>> index 12287d1..c708752 100644
>>>>>>>> --- a/hw/pci/pci-hotplug.c
>>>>>>>> +++ b/hw/pci/pci-hotplug.c
>>>>>>>> @@ -30,6 +30,8 @@
>>>>>>>>    #include "monitor/monitor.h"
>>>>>>>>    #include "hw/scsi/scsi.h"
>>>>>>>>    #include "hw/virtio/virtio-blk.h"
>>>>>>>> +#include "hw/virtio/virtio-scsi.h"
>>>>>>>> +#include "hw/virtio/virtio-pci.h"
>>>>>>>>    #include "qemu/config-file.h"
>>>>>>>>    #include "sysemu/blockdev.h"
>>>>>>>>    #include "qapi/error.h"
>>>>>>>> @@ -79,13 +81,26 @@ static int scsi_hot_add(Monitor *mon, DeviceState
>>>>>>>> *adapter,
>>>>>>>>    {
>>>>>>>>        SCSIBus *scsibus;
>>>>>>>>        SCSIDevice *scsidev;
>>>>>>>> +    VirtIOPCIProxy *virtio_proxy;
>>>>>>>>          scsibus = (SCSIBus *)
>>>>>>>>            object_dynamic_cast(OBJECT(QLIST_FIRST(&adapter->child_bus)),
>>>>>>>>                                TYPE_SCSI_BUS);
>>>>>>>>        if (!scsibus) {
>>>>>>>> -    error_report("Device is not a SCSI adapter");
>>>>>>>> -    return -1;
>>>>>>>> +        /*
>>>>>>>> +         * Check if the adapter is a virtio-scsi-pci, and forward
>>>>>>>> scsi_hot_add
>>>>>>>> +         * to the virtio-scsi-device.
>>>>>>>> +         */
>>>>>>>> +        if (!object_dynamic_cast(OBJECT(adapter),
>>>>>>>> TYPE_VIRTIO_SCSI_PCI)) {
>>>>>>>> +            error_report("Device is not a SCSI adapter");
>>>>>>>> +            return -1;
>>>>>>>> +        }
>>>>>>>> +        virtio_proxy = VIRTIO_PCI(adapter);
>>>>>>>> +        adapter = DEVICE(virtio_proxy->bus.vdev);
>>>>>>>> +        scsibus = (SCSIBus *)
>>>>>>>> +
>>>>>>>> object_dynamic_cast(OBJECT(QLIST_FIRST(&adapter->child_bus)),
>>>>>>>> +                            TYPE_SCSI_BUS);
>>>>>>>> +        assert(scsibus);
>>>>>>>>        }
>>>>>>>>          /*
>>
>> -- 
>> Alexey