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

Christoffer Dall
2014-06-08T10:09:24Z

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-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> ---
> 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?

-Christoffer