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

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

On 18/06/2013 17:21, Michael S. Tsirkin wrote:
> On Fri, Jun 14, 2013 at 08:13:29AM +0200, Frederic Konrad wrote:
>> On 13/06/2013 09:59, Michael S. Tsirkin wrote:
>>> On Thu, Jun 13, 2013 at 09:34:30AM +0200, Frederic Konrad wrote:
>>>> 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?
>>> Why not? This code:
>>>      scsibus = (SCSIBus *)
>>>          object_dynamic_cast(OBJECT(QLIST_FIRST(&adapter->child_bus)),
>>>                              TYPE_SCSI_BUS);
>>> should be replaced with code from qdev that we'll write
>>> that goes down the chain as long as there's 1 device
>>> on each bus, looking for a device of the appropriate type.
>> Ok, understood what you mean :).
>>
>> Why not if everybody is happy with it.
>>
>> Fred
> Ok so - want to try implementing this?

Ok, will try to look at it next week.

What about the stable release?
Wouldn't be safe to take this patch for the stable?

Fred
>
>>>>>>>>>>>> ---
>>>>>>>>>>>>    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