netdev - Re: [net-next 08/14] pci: Add SRIOV helper function to determine if VFs are assigned to guest

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Date:	Sat, 20 Apr 2013 20:31:28 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	davem@...emloft.net, Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Alexander Duyck <alexander.h.duyck@...el.com>,
	netdev@...r.kernel.org, gospo@...hat.com, sassmann@...hat.com,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: Re: [net-next 08/14] pci: Add SRIOV helper function to determine if
 VFs are assigned to guest

On Sat, 2013-04-20 at 02:49 -0700, Jeff Kirsher wrote:
> From: Alexander Duyck <alexander.h.duyck@...el.com>
> 
> This function is meant to add a helper function that will determine if a PF
> has any VFs that are currently assigned to a guest.  We currently have been
> implementing this function per driver, and going forward I would like to avoid
> that by making this function generic and using this helper.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>

Adding linux-pci mailing list and Bjorn to the CC.

Bjorn- David Miller needs a signoff by PCI maintainer. 

> ---
>  drivers/pci/iov.c   | 41 +++++++++++++++++++++++++++++++++++++++++
>  include/linux/pci.h |  5 +++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index ee599f2..fd99720 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -729,6 +729,47 @@ int pci_num_vf(struct pci_dev *dev)
>  EXPORT_SYMBOL_GPL(pci_num_vf);
>  
>  /**
> + * pci_vfs_assigned - returns number of VFs are assigned to a guest
> + * @dev: the PCI device
> + *
> + * Returns number of VFs belonging to this device that are assigned to a guest.
> + * If device is not a physical function returns -ENODEV.
> + */
> +int pci_vfs_assigned(struct pci_dev *dev)
> +{
> +	struct pci_dev *vfdev;
> +	unsigned int vfs_assigned = 0;
> +	unsigned short dev_id;
> +
> +	/* only search if we are a PF */
> +	if (!dev->is_physfn)
> +		return -ENODEV;
> +
> +	/*
> +	 * determine the device ID for the VFs, the vendor ID will be the
> +	 * same as the PF so there is no need to check for that one
> +	 */
> +	pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id);
> +
> +	/* loop through all the VFs to see if we own any that are assigned */
> +	vfdev = pci_get_device(dev->vendor, dev_id, NULL);
> +	while (vfdev) {
> +		/*
> +		 * It is considered assigned if it is a virtual function with
> +		 * our dev as the physical function and the assigned bit is set
> +		 */
> +		if (vfdev->is_virtfn && (vfdev->physfn == dev) &&
> +		    (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED))
> +			vfs_assigned++;
> +
> +		vfdev = pci_get_device(dev->vendor, dev_id, vfdev);
> +	}
> +
> +	return vfs_assigned;
> +}
> +EXPORT_SYMBOL_GPL(pci_vfs_assigned);
> +
> +/**
>   * pci_sriov_set_totalvfs -- reduce the TotalVFs available
>   * @dev: the PCI PF device
>   * @numvfs: number that should be used for TotalVFs supported
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 2461033a..03b4d3c 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1643,6 +1643,7 @@ extern int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
>  extern void pci_disable_sriov(struct pci_dev *dev);
>  extern irqreturn_t pci_sriov_migration(struct pci_dev *dev);
>  extern int pci_num_vf(struct pci_dev *dev);
> +extern int pci_vfs_assigned(struct pci_dev *dev);
>  extern int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
>  extern int pci_sriov_get_totalvfs(struct pci_dev *dev);
>  #else
> @@ -1661,6 +1662,10 @@ static inline int pci_num_vf(struct pci_dev *dev)
>  {
>  	return 0;
>  }
> +static inline int pci_vfs_assigned(struct pci_dev *dev)
> +{
> +	return 0;
> +}
>  static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
>  {
>  	return 0;



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