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

[Frederic Konrad]

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, address@hidden
> > > > > > > > > > > wrote:
> > > > > > > > > > > > From: KONRAD Frederic <address@hidden>
> > > > > > > > > > > >
> > > > > > > > > > > > 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: address@hidden
> > > > > > > > > > > > Reported-by: Alexey Kardashevskiy <address@hidden>
> > > > > > > > > > > > Reviewed-by: Andreas Färber <address@hidden>
> > > > > > > > > > > > Signed-off-by: KONRAD Frederic <address@hidden>
> > > > > > > > > > > Acked-by: Michael S. Tsirkin <address@hidden>
> > > > > > > > > > >
> > > > > > > > > > > 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 <address@hidden>
> > > > > >
> > > > > >
> > > > > > 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