Re: [PATCH v3 04/10] VFIO: platform: add vfio_platform_set_automasked

[Alex Williamson <alex.williamson@redhat.com>]

On Mon, 2015-08-10 at 15:20 +0200, Eric Auger wrote:
> This function makes possible to change the automasked mode.
> 
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> 
> ---
> 
> v1 -> v2:
> - set forwarded flag
> ---
>  drivers/vfio/platform/vfio_platform_irq.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index b31b1f0..a285384 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -186,6 +186,25 @@ static irqreturn_t vfio_handler(int irq, void *dev_id)
>  	return ret;
>  }
>  
> +static int vfio_platform_set_automasked(struct vfio_platform_irq *irq,
> +					   bool automasked)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&irq->lock, flags);
> +	if (automasked) {
> +		irq->forwarded = true;
> +		irq->flags |= VFIO_IRQ_INFO_AUTOMASKED;
> +		irq->handler = vfio_automasked_irq_handler;
> +	} else {
> +		irq->forwarded = false;
> +		irq->flags &= ~VFIO_IRQ_INFO_AUTOMASKED;
> +		irq->handler = vfio_irq_handler;
> +	}
> +	spin_unlock_irqrestore(&irq->lock, flags);
> +	return 0;

In vfio-speak, automasked means level and we're not magically changing
the IRQ from level to edge, we're simply able to handle level
differently based on a hardware optimization.  Should the user visible
flags therefore change based on this?  Aren't we really setting the
forwarded state rather than the automasked state?

> +}
> +
>  static void vfio_platform_irq_bypass_stop(struct irq_bypass_producer *prod)
>  {
>  }