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

[Bjorn Helgaas]

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 at linux.vnet.ibm.com>
> Signed-off-by: Juan J. Alvarez <jjalvare at 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?

> +#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)
>