linux-kernel - Re: [RFC PATCH v3 6/9] vfio/pci: export vfio_pci_setup

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Date:   Fri, 21 Feb 2020 01:20:21 -0500
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     Alex Williamson <alex.williamson@...hat.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "zhenyuw@...ux.intel.com" <zhenyuw@...ux.intel.com>,
        "Wang, Zhi A" <zhi.a.wang@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "He, Shaopeng" <shaopeng.he@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>
Subject: Re: [RFC PATCH v3 6/9] vfio/pci: export vfio_pci_setup_barmap

On Fri, Feb 21, 2020 at 05:00:13AM +0800, Alex Williamson wrote:
> On Tue, 11 Feb 2020 05:14:19 -0500
> Yan Zhao <yan.y.zhao@...el.com> wrote:
> 
> > This allows vendor driver to read/write to bars directly which is useful
> > in security checking condition.
> > 
> > Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> > ---
> >  drivers/vfio/pci/vfio_pci_rdwr.c | 26 +++++++++++++-------------
> >  include/linux/vfio.h             |  2 ++
> >  2 files changed, 15 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
> > index a0ef1de4f74a..3ba85fb2af5b 100644
> > --- a/drivers/vfio/pci/vfio_pci_rdwr.c
> > +++ b/drivers/vfio/pci/vfio_pci_rdwr.c
> > @@ -129,7 +129,7 @@ static ssize_t do_io_rw(void __iomem *io, char __user *buf,
> >  	return done;
> >  }
> >  
> > -static int vfio_pci_setup_barmap(struct vfio_pci_device *vdev, int bar)
> > +void __iomem *vfio_pci_setup_barmap(struct vfio_pci_device *vdev, int bar)
> >  {
> >  	struct pci_dev *pdev = vdev->pdev;
> >  	struct vfio_pci_device_private *priv = VDEV_TO_PRIV(vdev);
> > @@ -137,22 +137,23 @@ static int vfio_pci_setup_barmap(struct vfio_pci_device *vdev, int bar)
> >  	void __iomem *io;
> >  
> >  	if (priv->barmap[bar])
> > -		return 0;
> > +		return priv->barmap[bar];
> >  
> >  	ret = pci_request_selected_regions(pdev, 1 << bar, "vfio");
> >  	if (ret)
> > -		return ret;
> > +		return NULL;
> >  
> >  	io = pci_iomap(pdev, bar, 0);
> >  	if (!io) {
> >  		pci_release_selected_regions(pdev, 1 << bar);
> > -		return -ENOMEM;
> > +		return NULL;
> >  	}
> >  
> >  	priv->barmap[bar] = io;
> >  
> > -	return 0;
> > +	return io;
> >  }
> > +EXPORT_SYMBOL_GPL(vfio_pci_setup_barmap);
> 
> This should instead become a vfio_pci_get_barmap() function that tests
> for an optionally calls vfio_pci_setup_barmap before returning the
> pointer.  I'm now willing to lose the better error returns in the
> original.  Thanks,
>
Got it. will change it.
Thanks!

Yan