[libvirt] [PATCH v3 09/12] qemu: Generate and use zPCI device in QEMU command line

[Yi Min Zhao]

在 2018/8/22 下午4:42, Andrea Bolognani 写道:
> On Wed, 2018-08-22 at 11:06 +0800, Yi Min Zhao wrote:
>> 在 2018/8/20 下午7:14, Andrea Bolognani 写道:
>>> So which is unique: uid, fid, or the combination of the two?
>>> Could I have
>>>
>>>     -device zpci,uid=1,fid=1
>>>     -device zpci,uid=1,fid=2
>>>
>>> or would that not work? What about
>>>
>>>     -device zpci,uid=1,fid=1
>>>     -device zpci,uid=2,fid=1
>>>
>>> would that be okay?
>> Both can't work. FID must be unique and UID must be also unique.
>> They are independent.
> Got it, thanks.
>
>>> My point is that a funtion called fooIsBaz() should only ever
>>> check whether the foo in question is indeed a baz, without taking
>>> any other action such as reporting errors. Leave that to the
>>> caller, or give the function a different name.
>> I think moving to the caller is proper.
>>
>>> qemuDomainDeviceDefValidate() looks like a reasonable entry point
>>> for checks such as "you specified a zPCI address but this is not
>>> an s390 guest" or "your configuration requires zPCI but the QEMU
>>> binary doesn't support that feature". Both of the cases above
>>> should have proper test suite coverage, by the way.
>> How about my idea mentioned above?
> You mean moving the check to the caller?
Yes.
>
> I think qemuDomainDeviceDefValidate() is a better choice because
> it should allow you to implement the checks once, potentially with
> more context such as information about the domain and QEMU
> capabilities, and have them performed regardless of whether the
> device is being processed eg. during regular parsing or hotplug.
>
IIUC, in qemuDomainDeviceDefValidate(), we have to directly access
device_info from DeviceDef to check zpci. I think direct accessing is
insecure and we have to process those device types that has device_info.
In addition, these is a special case that address is not defined and pci
address type will be chosen by default.

I found there are a lot of caps check code while building command line.