linux-kernel - Re: [RFC PATCH v4 04/10] vfio/pci: let vfio_pci know number of vendor regions and vendor irqs

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Message-ID: <20200611230940.GD13961@joy-OptiPlex-7040>
Date:   Thu, 11 Jun 2020 19:09:40 -0400
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     David Edmondson <dme@....org>
Cc:     Cornelia Huck <cohuck@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        zhenyuw@...ux.intel.com, zhi.a.wang@...el.com,
        kevin.tian@...el.com, shaopeng.he@...el.com, yi.l.liu@...el.com,
        xin.zeng@...el.com, hang.yuan@...el.com
Subject: Re: [RFC PATCH v4 04/10] vfio/pci: let vfio_pci know number of
 vendor regions and vendor irqs

On Thu, Jun 11, 2020 at 01:31:05PM +0100, David Edmondson wrote:
> On Thursday, 2020-06-04 at 22:15:42 -04, Yan Zhao wrote:
> 
> > On Thu, Jun 04, 2020 at 05:25:15PM +0200, Cornelia Huck wrote:
> >> On Sun, 17 May 2020 22:49:44 -0400
> >> Yan Zhao <yan.y.zhao@...el.com> wrote:
> >> 
> >> > This allows a simpler VFIO_DEVICE_GET_INFO ioctl in vendor driver
> >> > 
> >> > Cc: Kevin Tian <kevin.tian@...el.com>
> >> > Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> >> > ---
> >> >  drivers/vfio/pci/vfio_pci.c         | 23 +++++++++++++++++++++--
> >> >  drivers/vfio/pci/vfio_pci_private.h |  2 ++
> >> >  include/linux/vfio.h                |  3 +++
> >> >  3 files changed, 26 insertions(+), 2 deletions(-)
> >> > 
> >> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> >> > index 290b7ab55ecf..30137c1c5308 100644
> >> > --- a/drivers/vfio/pci/vfio_pci.c
> >> > +++ b/drivers/vfio/pci/vfio_pci.c
> >> > @@ -105,6 +105,24 @@ void *vfio_pci_vendor_data(void *device_data)
> >> >  }
> >> >  EXPORT_SYMBOL_GPL(vfio_pci_vendor_data);
> >> >  
> >> > +int vfio_pci_set_vendor_regions(void *device_data, int num_vendor_regions)
> >> > +{
> >> > +	struct vfio_pci_device *vdev = device_data;
> >> > +
> >> > +	vdev->num_vendor_regions = num_vendor_regions;
> >> 
> >> Do we need any kind of sanity check here, in case this is called with a
> >> bogus value?
> >>
> > you are right. it at least needs to be >=0.
> > maybe type of "unsigned int" is more appropriate for num_vendor_regions.
> > we don't need to check its max value as QEMU would check it.
> 
> That seems like a bad precedent - the caller may not be QEMU.
>
but the caller has to query that through vfio_pci_ioctl() and at there
info.num_regions = VFIO_PCI_NUM_REGIONS + vdev->num_regions +  vdev->num_vendor_regions;         

info.num_regions is of type __u32.


Thanks
Yan