Re: [PATCH v1 1/3] powerpc/kernel: Split up pci_bus_add_device

["Bryant G. Ly" <bryantly@linux.vnet.ibm.com>]

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On 9/21/17 3:43 PM, Bjorn Helgaas wrote:
> On Mon, Sep 18, 2017 at 02:26:49PM -0500, Bryant G. Ly wrote:
>> When enabling SR-IOV one might want to have their
>> own version of starting device drivers for the VFs.
>> This patch allows for SR-IOV callers to use
>> pci_bus_add_virtfn_device instead of generic
>> pci_bus_add_device.
>>
>> When enabling SR-IOV in PSeries architecture the
>> dynamic VFs created within the sriov_configure sysfs call
>> will not load the device driver as firmware will load
>> the device node when the VF device is assigned to the
>> logical partition. So we needed a way to overwrite the
>> way device driver matching is done for virtual functions
>> on powervm.
>>
>> Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
>> Signed-off-by: Juan J. Alvarez <jjalvare@us.ibm.com>
>> ---
>>   drivers/pci/bus.c   | 51 ++++++++++++++++++++++++++++++++++++++++++---------
>>   drivers/pci/iov.c   |  2 +-
>>   include/linux/pci.h |  3 +++
>>   3 files changed, 46 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
>> index bc56cf19afd3..86daf62c4048 100644
>> --- a/drivers/pci/bus.c
>> +++ b/drivers/pci/bus.c
>> @@ -302,16 +302,9 @@ void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }
>>   
>>   void __weak pcibios_bus_add_device(struct pci_dev *pdev) { }
>>   
>> -/**
>> - * pci_bus_add_device - start driver for a single device
>> - * @dev: device to add
>> - *
>> - * This adds add sysfs entries and start device drivers
>> - */
>> -void pci_bus_add_device(struct pci_dev *dev)
>> -{
>> -	int retval;
>>   
>> +void pci_bus_add_sysfs_entries(struct pci_dev *dev)
>> +{
>>   	/*
>>   	 * Can not put in pci_device_add yet because resources
>>   	 * are not assigned yet for some devices.
>> @@ -321,6 +314,11 @@ void pci_bus_add_device(struct pci_dev *dev)
>>   	pci_create_sysfs_dev_files(dev);
>>   	pci_proc_attach_device(dev);
>>   	pci_bridge_d3_update(dev);
>> +}
>> +
>> +void pci_bus_match_device_driver(struct pci_dev *dev)
>> +{
>> +	int retval;
>>   
>>   	dev->match_driver = true;
>>   	retval = device_attach(&dev->dev);
>> @@ -333,6 +331,41 @@ void pci_bus_add_device(struct pci_dev *dev)
>>   
>>   	dev->is_added = 1;
>>   }
>> +
>> +#ifdef CONFIG_PCI_IOV
>> +void __weak pci_bus_match_virtfn_driver(struct pci_dev *dev)
>> +{
>> +	pci_bus_match_device_driver(dev);
>> +}
>> +
>> +/**
>> + * pci_bus_add_virtfn_device - start driver for a virtual function device
>> + * @dev: device to add
>> + *
>> + * This adds add sysfs entries and start device drivers for
>> + * virtual function devices
>> + *
>> + */
>> +void pci_bus_add_virtfn_device(struct pci_dev *pdev)
>> +{
>> +	pci_bus_add_sysfs_entries(pdev);
>> +	pci_bus_match_virtfn_driver(pdev);
>> +}
>> +EXPORT_SYMBOL_GPL(pci_bus_add_virtfn_device);
> Is there any way we can avoid adding this new interface?  I don't
> really want a new global exported symbol just to support this highly
> platform-specific functionality.
>
> If we could figure out a way to set dev->match_driver to false instead
> of true in pci_bus_add_device(), it *looks* like that would be enough
> to accomplish what you need.  Maybe that could be done via a pcibios
> hook or a new function pointer in struct pci_host_bridge, similar to
> the swizzle_irq pointer?

Yes! I will remove the first two patches in the series and only utilize the third
patch but addingpdev->match_driver = -1; under pseries_pcibios_bus_add_device, which is 
a new function I added for machine dependent bus add of a device. The 
patch will then require https://patchwork.kernel.org/patch/9882915/ 
which basically allows for match_driver state to not get changed later 
under the pci_bus_match due to allowing for the match_driver to be a int 
vs a bool. I will push up another patch removing the first two patches 
and adding that extra line. -Bryant

>> +#endif
>> +
>> +/**
>> + * pci_bus_add_device - start driver for a single device
>> + * @dev: device to add
>> + *
>> + * This adds add sysfs entries and start device drivers
>> + */
>> +void pci_bus_add_device(struct pci_dev *dev)
>> +{
>> +	pci_bus_add_sysfs_entries(dev);
>> +	pci_bus_match_device_driver(dev);
>> +}
>> +
>>   EXPORT_SYMBOL_GPL(pci_bus_add_device);
>>   
>>   /**
>> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>> index ac41c8be9200..16cc72545847 100644
>> --- a/drivers/pci/iov.c
>> +++ b/drivers/pci/iov.c
>> @@ -162,7 +162,7 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, int reset)
>>   
>>   	pci_device_add(virtfn, virtfn->bus);
>>   
>> -	pci_bus_add_device(virtfn);
>> +	pci_bus_add_virtfn_device(virtfn);
>>   	sprintf(buf, "virtfn%u", id);
>>   	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
>>   	if (rc)
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index f68c58a93dd0..39f5c0b4bf23 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -911,6 +911,9 @@ struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn);
>>   void pci_device_add(struct pci_dev *dev, struct pci_bus *bus);
>>   unsigned int pci_scan_child_bus(struct pci_bus *bus);
>>   void pci_bus_add_device(struct pci_dev *dev);
>> +#ifdef CONFIG_PCI_IOV
>> +void pci_bus_add_virtfn_device(struct pci_dev *dev);
>> +#endif
>>   void pci_read_bridge_bases(struct pci_bus *child);
>>   struct resource *pci_find_parent_resource(const struct pci_dev *dev,
>>   					  struct resource *res);
>> -- 
>> 2.11.0 (Apple Git-81)
>>


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