linux-kernel - Re: [pci PATCH v6 1/5] pci: Add pci_sriov_configure_simple for PFs that don't manage VF resources

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Message-ID: <20180314085421.GA28796@lst.de>
Date:   Wed, 14 Mar 2018 09:54:21 +0100
From:   Christoph Hellwig <hch@....de>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     bhelgaas@...gle.com, alexander.h.duyck@...el.com,
        linux-pci@...r.kernel.org, virtio-dev@...ts.oasis-open.org,
        kvm@...r.kernel.org, netdev@...r.kernel.org, dan.daly@...el.com,
        linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        keith.busch@...el.com, netanel@...zon.com, ddutile@...hat.com,
        mheyne@...zon.de, liang-min.wang@...el.com,
        mark.d.rustad@...el.com, dwmw2@...radead.org, hch@....de,
        dwmw@...zon.co.uk
Subject: Re: [pci PATCH v6 1/5] pci: Add pci_sriov_configure_simple for PFs
        that don't manage VF resources

On Tue, Mar 13, 2018 at 02:28:49PM -0700, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@...el.com>
> 
> This patch adds a common configuration function called
> pci_sriov_configure_simple that will allow for managing VFs on devices
> where the PF is not capable of managing VF resources.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> ---
> 
> v5: New patch replacing pci_sriov_configure_unmanaged with
>       pci_sriov_configure_simple
>     Dropped bits related to autoprobe changes
> v6: Defined pci_sriov_configure_simple as NULL if IOV is disabled
> 
>  drivers/pci/iov.c   |   32 ++++++++++++++++++++++++++++++++
>  include/linux/pci.h |    3 +++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 677924ae0350..bd7021491fdb 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -807,3 +807,35 @@ int pci_sriov_get_totalvfs(struct pci_dev *dev)
>  	return dev->sriov->total_VFs;
>  }
>  EXPORT_SYMBOL_GPL(pci_sriov_get_totalvfs);
> +
> +/**
> + * pci_sriov_configure_simple - helper to configure unmanaged SR-IOV
> + * @dev: the PCI device
> + * @nr_virtfn: number of virtual functions to enable, 0 to disable
> + *
> + * Used to provide generic enable/disable SR-IOV option for devices
> + * that do not manage the VFs generated by their driver
> + */
> +int pci_sriov_configure_simple(struct pci_dev *dev, int nr_virtfn)
> +{
> +	int err = -EINVAL;

This assignment seems like it is never used..

> +
> +	might_sleep();
> +
> +	if (!dev->is_physfn)
> +		return -ENODEV;
> +
> +	if (pci_vfs_assigned(dev)) {
> +		pci_warn(dev,
> +			 "Cannot modify SR-IOV while VFs are assigned\n");
> +		err = -EPERM;

Why not:

	if (pci_vfs_assigned(dev)) {
		pci_warn(dev,
			 "Cannot modify SR-IOV while VFs are assigned\n");
		return -EPERM;
	}

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@....de>