Re: [Xen-devel] [PATCH v2] xen/pciback: support driver_override

[Juergen Gross <jgross@suse.com>]

On 09/09/16 16:27, David Vrabel wrote:
> On 09/09/16 07:14, Juergen Gross wrote:
>> On 08/09/16 16:10, Boris Ostrovsky wrote:
>>> On 09/02/2016 08:30 AM, Juergen Gross wrote:
>>>> Support the driver_override scheme introduced with commit 782a985d7af2
>>>> ("PCI: Introduce new device binding path using pci_dev.driver_override")
>>>>
>>>> As pcistub_probe() is called for all devices (it has to check for a
>>>> match based on the slot address rather than device type) it has to
>>>> check for driver_override set to "pciback" itself.
>>>>
>>>> Signed-off-by: Juergen Gross <jgross@suse.com>
>>>> ---
>>>> V2: removed now unused label
>>>> ---
>>>>  drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++------
>>>>  1 file changed, 10 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
>>>> index 258b7c3..85c28f7 100644
>>>> --- a/drivers/xen/xen-pciback/pci_stub.c
>>>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>>>> @@ -25,6 +25,8 @@
>>>>  #include "conf_space.h"
>>>>  #include "conf_space_quirks.h"
>>>>  
>>>> +#define PCISTUB_DRIVER_NAME "pciback"
>>>> +
>>>>  static char *pci_devs_to_hide;
>>>>  wait_queue_head_t xen_pcibk_aer_wait_queue;
>>>>  /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
>>>> @@ -529,16 +531,18 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
>>>>  				"don't have a normal (0) or bridge (1) "
>>>>  				"header type!\n");
>>>>  			err = -ENODEV;
>>>> -			goto out;
>>>>  		}
>>>>  
>>>> +	} else if (!dev->driver_override ||
>>>> +		   strcmp(dev->driver_override, PCISTUB_DRIVER_NAME))
>>>> +		/* Didn't find the device */
>>>> +		err = -ENODEV;
>>>> +
>>>> +	if (!err) {
>>>>  		dev_info(&dev->dev, "seizing device\n");
>>>>  		err = pcistub_seize(dev);
>>>> -	} else
>>>> -		/* Didn't find the device */
>>>> -		err = -ENODEV;
>>>> +	}
>>>
>>> Should devices with pciback override be displayed in
>>> /sys/bus/pci/drivers/pciback/slots? If they should then they need to be
>>> either added to pcistub_device_ids or kept on some other list.
>>
>> No, I don't think so. The patch is just needed to _avoid_ having to use
>> the slots stuff: without the patch you need something like:
>>
>> echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind
>> echo 0000:07:10.0 > /sys/bus/pci/drivers/pciback/new_slot
>> echo 0000:07:10.0 > /sys/bus/pci/drivers_probe
>>
>> while with the patch you can use the same mechanism as for similar
>> drivers like pci-stub and vfio-pci:
>>
>> echo pciback > /sys/bus/pci/devices/0000\:07\:10.0/driver_override
>> echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind
>> echo 0000:07:10.0 > /sys/bus/pci/drivers_probe
>>
>> So e.g. libvirt doesn't need special handling for pciback. The slot list
>> is necessary for assigning devices to pciback on boot, but I think the
>> override mechanism is better for runtime assignment.
> 
> Can you include something like this in the commit message?

Okay.


Juergen