Subject: Re: [PATCH V7 01/17] PCI/IOV: Export interface for retrieve VF's BDF

From: Bjorn Helgaas <[email-masked]>
Date: Tue, 19 Aug 2014 15:37:26 -0600

On Thu, Jul 24, 2014 at 02:22:11PM +0800, Wei Yang wrote:
> When implementing the SR-IOV on PowerNV platform, some resource reservation is
> needed for VFs which don't exist at the bootup stage. To do the match between
> resources and VFs, the code need to get the VF's BDF in advance.

Ben started explaining this whole hardware PE/VF/etc stuff to me, but it
hasn't all sunk in yet.  We need to describe it somewhere (it sounds pretty
involved, so maybe an extended description in Documentation/ would be
appropriate).

What I'm concerned about is that PCI resource assignment is a huge mess,
and this obviously complicates it even more.  That's necessary and OK, but
I want to at least preserve the possibility that somebody could rework it
to make it manageable, and that means we need to know what the special
constraints of PowerNV are.

Code question below.

> In this patch, it exports the interface to retrieve VF's BDF:
>    * Make the virtfn_bus as an interface
>    * Make the virtfn_devfn as an interface
>    * rename them with more specific name
>    * code cleanup in pci_sriov_resource_alignment()
> 
> Signed-off-by: Wei Yang <[email-masked]>
> ---
>  drivers/pci/iov.c   |   26 +++++++-------------------
>  drivers/pci/pci.h   |   19 -------------------
>  include/linux/pci.h |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 51 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index cb6f247..7566238 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -19,18 +19,6 @@
>  
>  #define VIRTFN_ID_LEN	16
>  
> -static inline u8 virtfn_bus(struct pci_dev *dev, int id)
> -{
> -	return dev->bus->number + ((dev->devfn + dev->sriov->offset +
> -				    dev->sriov->stride * id) >> 8);
> -}
> -
> -static inline u8 virtfn_devfn(struct pci_dev *dev, int id)
> -{
> -	return (dev->devfn + dev->sriov->offset +
> -		dev->sriov->stride * id) & 0xff;
> -}
> -
>  static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
>  {
>  	struct pci_bus *child;
> @@ -69,7 +57,7 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
>  	struct pci_bus *bus;
>  
>  	mutex_lock(&iov->dev->sriov->lock);
> -	bus = virtfn_add_bus(dev->bus, virtfn_bus(dev, id));
> +	bus = virtfn_add_bus(dev->bus, pci_iov_virtfn_bus(dev, id));
>  	if (!bus)
>  		goto failed;
>  
> @@ -77,7 +65,7 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
>  	if (!virtfn)
>  		goto failed0;
>  
> -	virtfn->devfn = virtfn_devfn(dev, id);
> +	virtfn->devfn = pci_iov_virtfn_devfn(dev, id);
>  	virtfn->vendor = dev->vendor;
>  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_DID, &virtfn->device);
>  	pci_setup_device(virtfn);
> @@ -140,8 +128,8 @@ static void virtfn_remove(struct pci_dev *dev, int id, int reset)
>  	struct pci_sriov *iov = dev->sriov;
>  
>  	virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),
> -					     virtfn_bus(dev, id),
> -					     virtfn_devfn(dev, id));
> +					     pci_iov_virtfn_bus(dev, id),
> +					     pci_iov_virtfn_devfn(dev, id));
>  	if (!virtfn)
>  		return;
>  
> @@ -216,7 +204,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>  	iov->offset = offset;
>  	iov->stride = stride;
>  
> -	if (virtfn_bus(dev, nr_virtfn - 1) > dev->bus->busn_res.end) {
> +	if (pci_iov_virtfn_bus(dev, nr_virtfn - 1) > dev->bus->busn_res.end) {
>  		dev_err(&dev->dev, "SR-IOV: bus number out of range\n");
>  		return -ENOMEM;
>  	}
> @@ -516,7 +504,7 @@ resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno)
>  	if (!reg)
>  		return 0;
>  
> -	 __pci_read_base(dev, type, &tmp, reg);
> +	__pci_read_base(dev, type, &tmp, reg);
>  	return resource_alignment(&tmp);
>  }
>  
> @@ -546,7 +534,7 @@ int pci_iov_bus_range(struct pci_bus *bus)
>  	list_for_each_entry(dev, &bus->devices, bus_list) {
>  		if (!dev->is_physfn)
>  			continue;
> -		busnr = virtfn_bus(dev, dev->sriov->total_VFs - 1);
> +		busnr = pci_iov_virtfn_bus(dev, dev->sriov->total_VFs - 1);
>  		if (busnr > max)
>  			max = busnr;
>  	}
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 0601890..a3158b2 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -221,25 +221,6 @@ static inline int pci_ari_enabled(struct pci_bus *bus)
>  void pci_reassigndev_resource_alignment(struct pci_dev *dev);
>  void pci_disable_bridge_window(struct pci_dev *dev);
>  
> -/* Single Root I/O Virtualization */
> -struct pci_sriov {
> -	int pos;		/* capability position */
> -	int nres;		/* number of resources */
> -	u32 cap;		/* SR-IOV Capabilities */
> -	u16 ctrl;		/* SR-IOV Control */
> -	u16 total_VFs;		/* total VFs associated with the PF */
> -	u16 initial_VFs;	/* initial VFs associated with the PF */
> -	u16 num_VFs;		/* number of VFs available */
> -	u16 offset;		/* first VF Routing ID offset */
> -	u16 stride;		/* following VF stride */
> -	u32 pgsz;		/* page size for BAR alignment */
> -	u8 link;		/* Function Dependency Link */
> -	u16 driver_max_VFs;	/* max num VFs driver supports */
> -	struct pci_dev *dev;	/* lowest numbered PF */
> -	struct pci_dev *self;	/* this PF */
> -	struct mutex lock;	/* lock for VF bus */
> -};
> -
>  #ifdef CONFIG_PCI_ATS
>  void pci_restore_ats_state(struct pci_dev *dev);
>  #else
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 466bcd1..194db52 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -245,6 +245,27 @@ struct pci_vpd;
>  struct pci_sriov;
>  struct pci_ats;
>  
> +/* Single Root I/O Virtualization */
> +struct pci_sriov {
> +	int pos;		/* capability position */
> +	int nres;		/* number of resources */
> +	u32 cap;		/* SR-IOV Capabilities */
> +	u16 ctrl;		/* SR-IOV Control */
> +	u16 total_VFs;		/* total VFs associated with the PF */
> +	u16 initial_VFs;	/* initial VFs associated with the PF */
> +	u16 num_VFs;		/* number of VFs available */
> +	u16 offset;		/* first VF Routing ID offset */
> +	u16 stride;		/* following VF stride */
> +	u32 pgsz;		/* page size for BAR alignment */
> +	u8 link;		/* Function Dependency Link */
> +	u16 driver_max_VFs;	/* max num VFs driver supports */
> +	struct pci_dev *dev;	/* lowest numbered PF */
> +	struct pci_dev *self;	/* this PF */
> +	struct mutex lock;	/* lock for VF bus */
> +	struct work_struct mtask; /* VF Migration task */
> +	u8 __iomem *mstate;	/* VF Migration State Array */
> +};
> +
>  /*
>   * The pci_dev structure is used to describe PCI devices.
>   */
> @@ -1616,6 +1637,21 @@ int pci_ext_cfg_avail(void);
>  void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar);
>  
>  #ifdef CONFIG_PCI_IOV
> +static inline int pci_iov_virtfn_bus(struct pci_dev *dev, int id)
> +{
> +	if (!dev->is_physfn)
> +		return -EINVAL;
> +	return dev->bus->number + ((dev->devfn + dev->sriov->offset +
> +				    dev->sriov->stride * id) >> 8);
> +}
> +static inline int pci_iov_virtfn_devfn(struct pci_dev *dev, int id)
> +{
> +	if (!dev->is_physfn)
> +		return -EINVAL;
> +	return (dev->devfn + dev->sriov->offset +
> +		dev->sriov->stride * id) & 0xff;
> +}

Do these really need to be inline?  If they weren't inline, we wouldn't
have to move struct pci_sriov to the public header file.

> +
>  int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
>  void pci_disable_sriov(struct pci_dev *dev);
>  int pci_num_vf(struct pci_dev *dev);
> @@ -1623,6 +1659,14 @@ int pci_vfs_assigned(struct pci_dev *dev);
>  int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
>  int pci_sriov_get_totalvfs(struct pci_dev *dev);
>  #else
> +static inline int pci_iov_virtfn_bus(struct pci_dev *dev, int id)
> +{
> +	return -ENXIO;
> +}
> +static inline int pci_iov_virtfn_devfn(struct pci_dev *dev, int id)
> +{
> +	return -ENXIO;
> +}
>  static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
>  { return -ENODEV; }
>  static inline void pci_disable_sriov(struct pci_dev *dev) { }
> -- 
> 1.7.9.5
>