On Mon, 2014-10-27 at 19:07 +0100, Antonios Motakis wrote:
> Level sensitive interrupts are exposed as maskable and automasked
> interrupts and are masked and disabled automatically when they fire.
> 
> Signed-off-by: Antonios Motakis <a.mota...@virtualopensystems.com>
> ---
>  drivers/vfio/platform/vfio_platform_irq.c     | 102 
> +++++++++++++++++++++++++-
>  drivers/vfio/platform/vfio_platform_private.h |   2 +
>  2 files changed, 100 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c 
> b/drivers/vfio/platform/vfio_platform_irq.c
> index 2ac8ed7..563abf6 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -31,18 +31,108 @@
>  
>  #include "vfio_platform_private.h"
>  
> +static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
> +{
> +     unsigned long flags;
> +
> +     spin_lock_irqsave(&irq_ctx->lock, flags);
> +
> +     if (!irq_ctx->masked) {
> +             disable_irq(irq_ctx->hwirq);
> +             irq_ctx->masked = true;
> +     }
> +
> +     spin_unlock_irqrestore(&irq_ctx->lock, flags);
> +}
> +
>  static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
>                                   unsigned index, unsigned start,
>                                   unsigned count, uint32_t flags, void *data)
>  {
> -     return -EINVAL;
> +     if (start != 0 || count != 1)
> +             return -EINVAL;
> +
> +     if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
> +             return -EINVAL;
> +
> +     if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
> +             return -EINVAL; /* not implemented yet */
> +
> +     if (flags & VFIO_IRQ_SET_DATA_NONE) {
> +             vfio_platform_mask(&vdev->irqs[index]);
> +
> +     } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
> +             uint8_t mask = *(uint8_t *)data;
> +
> +             if (mask)
> +                     vfio_platform_mask(&vdev->irqs[index]);
> +     }
> +
> +     return 0;
> +}
> +
> +static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
> +{
> +     unsigned long flags;
> +
> +     spin_lock_irqsave(&irq_ctx->lock, flags);
> +
> +     if (irq_ctx->masked) {
> +             enable_irq(irq_ctx->hwirq);
> +             irq_ctx->masked = false;
> +     }
> +
> +     spin_unlock_irqrestore(&irq_ctx->lock, flags);
>  }
>  
>  static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
>                                   unsigned index, unsigned start,
>                                   unsigned count, uint32_t flags, void *data)
>  {
> -     return -EINVAL;
> +     if (start != 0 || count != 1)
> +             return -EINVAL;
> +
> +     if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
> +             return -EINVAL;
> +
> +     if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
> +             return -EINVAL; /* not implemented yet */
> +
> +     if (flags & VFIO_IRQ_SET_DATA_NONE) {
> +             vfio_platform_unmask(&vdev->irqs[index]);
> +
> +     } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
> +             uint8_t unmask = *(uint8_t *)data;
> +
> +             if (unmask)
> +                     vfio_platform_unmask(&vdev->irqs[index]);
> +     }
> +
> +     return 0;
> +}
> +
> +static irqreturn_t vfio_maskable_irq_handler(int irq, void *dev_id)
> +{
> +     struct vfio_platform_irq *irq_ctx = dev_id;
> +     unsigned long flags;
> +     int ret = IRQ_NONE;
> +
> +     spin_lock_irqsave(&irq_ctx->lock, flags);
> +
> +     if (!irq_ctx->masked) {
> +             ret = IRQ_HANDLED;
> +
> +             /* automask maskable interrupts */
> +             disable_irq_nosync(irq_ctx->hwirq);
> +             irq_ctx->masked = true;
> +     }
> +
> +     spin_unlock_irqrestore(&irq_ctx->lock, flags);
> +
> +     if (ret == IRQ_HANDLED)
> +             eventfd_signal(irq_ctx->trigger, 1);
> +
> +     return ret;

This is not just a maskable irq handler, but specifically a level (aka
automasked) handler.  So this should only be used for AUTOMASKED irqs.

>  }
>  
>  static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
> @@ -103,7 +193,7 @@ static int vfio_platform_set_irq_trigger(struct 
> vfio_platform_device *vdev,
>       irq_handler_t handler;
>  
>       if (vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE)
> -             return -EINVAL; /* not implemented */
> +             handler = vfio_maskable_irq_handler;

As noted in the previous patch, this should be a test for AUTOMASKED,
not just MASKABLE.

>       else
>               handler = vfio_irq_handler;
>  
> @@ -175,13 +265,17 @@ int vfio_platform_irq_init(struct vfio_platform_device 
> *vdev)
>               if (hwirq < 0)
>                       goto err;
>  
> +             spin_lock_init(&vdev->irqs[i].lock);
> +
>               vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
>  
>               if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK)
> -                     vdev->irqs[i].flags |= VFIO_IRQ_INFO_MASKABLE;
> +                     vdev->irqs[i].flags |= VFIO_IRQ_INFO_MASKABLE
> +                                             | VFIO_IRQ_INFO_AUTOMASKED;
>  
>               vdev->irqs[i].count = 1;
>               vdev->irqs[i].hwirq = hwirq;
> +             vdev->irqs[i].masked = false;
>       }
>  
>       vdev->num_irqs = cnt;
> diff --git a/drivers/vfio/platform/vfio_platform_private.h 
> b/drivers/vfio/platform/vfio_platform_private.h
> index a3f2411..d25c4cd 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -30,6 +30,8 @@ struct vfio_platform_irq {
>       int                     hwirq;
>       char                    *name;
>       struct eventfd_ctx      *trigger;
> +     bool                    masked;
> +     spinlock_t              lock;
>  };
>  
>  struct vfio_platform_region {



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