On Wed, Nov 12, 2014 at 5:36 PM, Alex Williamson
<alex.williamson@xxxxxxxxxx> wrote:
> On Wed, 2014-11-12 at 11:32 +0100, Eric Auger wrote:
>> On 10/27/2014 07:07 PM, Antonios Motakis wrote:
>> > A VFIO userspace driver will start by opening the VFIO device
>> > that corresponds to an IOMMU group, and will use the ioctl interface
>> > to get the basic device info, such as number of memory regions and
>> > interrupts, and their properties. This patch enables the
>> > VFIO_DEVICE_GET_INFO ioctl call.
>> >
>> > Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
>> > ---
>> > drivers/vfio/platform/vfio_platform_common.c | 23 ++++++++++++++++++++---
>> > 1 file changed, 20 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
>> > index e0fdbc8..cb20526 100644
>> > --- a/drivers/vfio/platform/vfio_platform_common.c
>> > +++ b/drivers/vfio/platform/vfio_platform_common.c
>> > @@ -43,10 +43,27 @@ static int vfio_platform_open(void *device_data)
>> > static long vfio_platform_ioctl(void *device_data,
>> > unsigned int cmd, unsigned long arg)
>> > {
>> > - if (cmd == VFIO_DEVICE_GET_INFO)
>> > - return -EINVAL;
>> > + struct vfio_platform_device *vdev = device_data;
>> > + unsigned long minsz;
>> > +
>> > + if (cmd == VFIO_DEVICE_GET_INFO) {
>> > + struct vfio_device_info info;
>> > +
>> > + minsz = offsetofend(struct vfio_device_info, num_irqs);
>> > +
>> > + if (copy_from_user(&info, (void __user *)arg, minsz))
>> > + return -EFAULT;
>> > +
>> > + if (info.argsz < minsz)
>> > + return -EINVAL;
>> > +
>> > + info.flags = vdev->flags;
>> > + info.num_regions = 0;
>> > + info.num_irqs = 0;
>> Seems a bit weird to me to enable the modality but returning zeroed
>> values. Shouldn't we put that patch after VFIO_DEVICE_GET_REGION_INFO
>> and VFIO_DEVICE_GET_IRQ_INFO ones?
>
> I actually like how Antonios has started from a base framework, exposing
> a device but none of the resources and then incrementally adds each
> component. It's also a good showcase of the VFIO ABI that we can do
> things like this. Thanks,
I also agree with Alex with this. But of course I'm not married with
any particular splitting style, in case we decide to change this.
>
> Alex
>
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