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

From: Yan Zhao <yan.y.zhao@intel.com>
To: David Edmondson <dme@dme.org>
Cc: Cornelia Huck <cohuck@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	alex.williamson@redhat.com, zhenyuw@linux.intel.com,
	zhi.a.wang@intel.com, kevin.tian@intel.com,
	shaopeng.he@intel.com, yi.l.liu@intel.com, xin.zeng@intel.com,
	hang.yuan@intel.com
Subject: Re: [RFC PATCH v4 04/10] vfio/pci: let vfio_pci know number of vendor regions and vendor irqs
Date: Thu, 11 Jun 2020 19:09:40 -0400	[thread overview]
Message-ID: <20200611230940.GD13961@joy-OptiPlex-7040> (raw)
In-Reply-To: <m23671943a.fsf@dme.org>

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@intel.com> wrote:
> >> 
> >> > This allows a simpler VFIO_DEVICE_GET_INFO ioctl in vendor driver
> >> > 
> >> > Cc: Kevin Tian <kevin.tian@intel.com>
> >> > Signed-off-by: Yan Zhao <yan.y.zhao@intel.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