Re: [RFC PATCH v6 14/20] vfio/platform: initial interrupts support

[Antonios Motakis]

On Sun, Jun 8, 2014 at 12:09 PM, Christoffer Dall
<christoffer.dall@xxxxxxxxxx> wrote:
>
> On Thu, Jun 05, 2014 at 07:03:22PM +0200, Antonios Motakis wrote:
> > This patch allows to set an eventfd for a patform device's interrupt,
> > and also to trigger the interrupt eventfd from userspace for testing.
> >
> > Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
> > ---
> >  drivers/vfio/platform/vfio_platform.c         |  36 ++++++-
> >  drivers/vfio/platform/vfio_platform_irq.c     | 130 +++++++++++++++++++++++++-
> >  drivers/vfio/platform/vfio_platform_private.h |   7 ++
> >  3 files changed, 169 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
> > index 192291c..f4c06c6 100644
> > --- a/drivers/vfio/platform/vfio_platform.c
> > +++ b/drivers/vfio/platform/vfio_platform.c
> > @@ -177,10 +177,40 @@ static long vfio_platform_ioctl(void *device_data,
> >
> >               return copy_to_user((void __user *)arg, &info, minsz);
> >
> > -     } else if (cmd == VFIO_DEVICE_SET_IRQS)
> > -             return -EINVAL;
> > +     } else if (cmd == VFIO_DEVICE_SET_IRQS) {
> > +             struct vfio_irq_set hdr;
> > +             int ret = 0;
> > +
> > +             minsz = offsetofend(struct vfio_irq_set, count);
> > +
> > +             if (copy_from_user(&hdr, (void __user *)arg, minsz))
> > +                     return -EFAULT;
> > +
> > +             if (hdr.argsz < minsz)
> > +                     return -EINVAL;
> > +
> > +             if (hdr.index >= vdev->num_irqs)
> > +                     return -EINVAL;
> > +
> > +             if (hdr.start != 0 || hdr.count > 1)
> > +                     return -EINVAL;
> > +
> > +             if (hdr.count == 0 &&
> > +                     (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE) ||
> > +                      !(hdr.flags & VFIO_IRQ_SET_ACTION_TRIGGER)))
> > +                     return -EINVAL;
> > +
> > +             if (hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
> > +                               VFIO_IRQ_SET_ACTION_TYPE_MASK))
> > +                     return -EINVAL;
> > +
> > +             ret = vfio_platform_set_irqs_ioctl(vdev, hdr.flags, hdr.index,
> > +                                                hdr.start, hdr.count,
> > +                                                (void *)arg+minsz);
> > +
> > +             return ret;
> >
> > -     else if (cmd == VFIO_DEVICE_RESET)
> > +     } else if (cmd == VFIO_DEVICE_RESET)
> >               return -EINVAL;
> >
> >       return -ENOTTY;
> > diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> > index 22c214f..d79f5af 100644
> > --- a/drivers/vfio/platform/vfio_platform_irq.c
> > +++ b/drivers/vfio/platform/vfio_platform_irq.c
> > @@ -31,6 +31,9 @@
> >
> >  #include "vfio_platform_private.h"
> >
> > +static int vfio_set_trigger(struct vfio_platform_device *vdev,
> > +                         int index, int fd);
> > +
> >  int vfio_platform_irq_init(struct vfio_platform_device *vdev)
> >  {
> >       int cnt = 0, i;
> > @@ -43,17 +46,142 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
> >               return -ENOMEM;
> >
> >       for (i = 0; i < cnt; i++) {
> > -             vdev->irq[i].flags = 0;
> > +             int hwirq = platform_get_irq(vdev->pdev, i);
> > +
> > +             if (hwirq < 0)
> > +                     goto err;
> > +
> > +             vdev->irq[i].flags = VFIO_IRQ_INFO_EVENTFD;
> >               vdev->irq[i].count = 1;
> > +             vdev->irq[i].hwirq = hwirq;
> >       }
> >
> >       vdev->num_irqs = cnt;
> >
> >       return 0;
> > +err:
> > +     kfree(vdev->irq);
> > +     return -EINVAL;
> >  }
> >
> >  void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
> >  {
> > +     int i;
> > +
> > +     for (i = 0; i < vdev->num_irqs; i++)
> > +             vfio_set_trigger(vdev, i, -1);
> > +
> >       vdev->num_irqs = 0;
> >       kfree(vdev->irq);
> >  }
> > +
> > +static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
> > +{
> > +     struct eventfd_ctx *trigger = dev_id;
> > +
> > +     eventfd_signal(trigger, 1);
> > +
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +static int vfio_set_trigger(struct vfio_platform_device *vdev,
> > +                         int index, int fd)
> > +{
> > +     struct vfio_platform_irq *irq = &vdev->irq[index];
> > +     struct eventfd_ctx *trigger;
> > +     int ret;
> > +
> > +     if (irq->trigger) {
> > +             free_irq(irq->hwirq, irq);
> > +             kfree(irq->name);
> > +             eventfd_ctx_put(irq->trigger);
> > +             irq->trigger = NULL;
> > +     }
>
> this feels incredibly racy, is some lock protecting this access?
>

Good catch; there should have been a mutex earlier protecting it, but
it is missing. Thanks.

> -Christoffer




-- 
Antonios Motakis
Virtual Open Systems
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