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

Antonios Motakis
2014-09-02T16:07:25Z

On Sun, Jun 8, 2014 at 12:09 PM, Christoffer Dall
<christoffer.dall@linaro.org> 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@virtualopensystems.com>
> > ---
> > 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