Re: [Qemu-devel] [PATCH 13/13] qdev-properties: Add pci-devaddr property

[Jan Kiszka <jan.kiszka@web.de>]

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On 2012-06-10 12:49, Michael S. Tsirkin wrote:
> On Sun, Jun 10, 2012 at 12:14:36PM +0200, Jan Kiszka wrote:
>> On 2012-06-10 11:35, Michael S. Tsirkin wrote:
>>> On Mon, Jun 04, 2012 at 10:52:21AM +0200, Jan Kiszka wrote:
>>>> Add a property to receive a fully qualified PCI device address.
>>>>
>>>> Will be used by KVM device assignment.
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>
>>> I'd like to ponder this a bit more.  What bothers me is that this mixes
>>> two things:
>>> 	- addressing of qemu devices
>>> 		Using full device addresses there is a legacy feature,
>>> 		users really should supply the parent bus and
>>> 		the bus local address.
>>> 	- addressing devices on the linux host for assignment
>>> 		It so happens that the syntax matches
>>> 		the legacy naming very closely,
>>> 		but conceptually is completely unrelated
>>
>> We can keep code duplications, of course.
>>
>>>
>>>> ---
>>>>  hw/qdev-properties.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>>  hw/qdev.h            |    3 +++
>>>>  2 files changed, 51 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
>>>> index 32e41f1..6634f22 100644
>>>> --- a/hw/qdev-properties.c
>>>> +++ b/hw/qdev-properties.c
>>>> @@ -946,6 +946,54 @@ PropertyInfo qdev_prop_pci_devfn = {
>>>>      .max   = 0xFFFFFFFFULL,
>>>>  };
>>>>  
>>>> +static void get_pci_devaddr(Object *obj, Visitor *v, void *opaque,
>>>> +                            const char *name, Error **errp)
>>>> +{
>>>> +    DeviceState *dev = DEVICE(obj);
>>>> +    Property *prop = opaque;
>>>> +    PCIDeviceAddress *addr = qdev_get_prop_ptr(dev, prop);
>>>> +    char buffer[10 + 3 + 1];
>>>> +    char *p = buffer;
>>>> +
>>>> +    snprintf(buffer, sizeof(buffer), "%04x:%02x:%02x.%02x",
>>>> +             addr->domain, addr->bus, addr->slot, addr->function);
>>>> +
>>>> +    visit_type_str(v, &p, name, errp);
>>>> +}
>>>> +
>>>> +static void set_pci_devaddr(Object *obj, Visitor *v, void *opaque,
>>>> +                            const char *name, Error **errp)
>>>> +{
>>>> +    DeviceState *dev = DEVICE(obj);
>>>> +    Property *prop = opaque;
>>>> +    PCIDeviceAddress *addr = qdev_get_prop_ptr(dev, prop);
>>>> +    Error *local_err = NULL;
>>>> +    char *str;
>>>> +
>>>> +    if (dev->state != DEV_STATE_CREATED) {
>>>> +        error_set(errp, QERR_PERMISSION_DENIED);
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    visit_type_str(v, &str, name, &local_err);
>>>> +    if (local_err) {
>>>> +        error_propagate(errp, local_err);
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (qemu_parse_pci_devaddr(str, addr,
>>>> +                               PCI_DEVADDR_WITH_DOM_BUS_OPT |
>>>> +                               PCI_DEVADDR_WITH_FUNC) < 0) {
>>>> +        error_set_from_qdev_prop_error(errp, EINVAL, dev, prop, str);
>>>> +    }
>>>> +}
>>>> +
>>>> +PropertyInfo qdev_prop_pci_devaddr = {
>>>> +    .name  = "pci-devaddr",
>>>
>>> This is a very confusing name.  Something like host-pci-address?
>>
>> That might be an option.
>>
>>> This also should be built on linux only.
>>
>> Why, what do we gain with #ifdefs? And isn't the addressing concept generic?
> 
> Not the XXX:XX.X format. And not the concept of a domain.
> 
>>> Can this be part of device assignment code instead of qdev?
>>
>> How does VFIO address their host devices?
> 
> You get an fd I think. I think you don't need to know the host address.

vfio_pci.c contains a nice function called "parse_hostaddr". You may
guess what it does. ;)

So we need this generic service. Let's called it pci-host-devaddr and be
fine?

Jan


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