Re: [PATCH v3 01/10] VFIO: platform: registration of a dummy IRQ bypass producer

From: Alex Williamson
Date: Wed Aug 12 2015 - 14:56:16 EST


On Mon, 2015-08-10 at 15:20 +0200, Eric Auger wrote:
> Register a dummy producer with void callbacks
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>
> ---
>
> v2 -> v3:
> - rename vfio_platform_irq_bypass_resume into *_start
> ---
> drivers/vfio/platform/vfio_platform_irq.c | 32 +++++++++++++++++++++++++++
> drivers/vfio/platform/vfio_platform_private.h | 2 ++
> 2 files changed, 34 insertions(+)
>
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index 88bba57..b5cb8c7 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -20,6 +20,7 @@
> #include <linux/types.h>
> #include <linux/vfio.h>
> #include <linux/irq.h>
> +#include <linux/irqbypass.h>
>
> #include "vfio_platform_private.h"
>
> @@ -177,6 +178,27 @@ static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
> return IRQ_HANDLED;
> }
>
> +static void vfio_platform_irq_bypass_stop(struct irq_bypass_producer *prod)
> +{
> +}
> +
> +static void vfio_platform_irq_bypass_start(struct irq_bypass_producer *prod)
> +{
> +}
> +
> +static int vfio_platform_irq_bypass_add_consumer(
> + struct irq_bypass_producer *prod,
> + struct irq_bypass_consumer *cons)
> +{
> + return 0;
> +}
> +
> +static void vfio_platform_irq_bypass_del_consumer(
> + struct irq_bypass_producer *prod,
> + struct irq_bypass_consumer *cons)
> +{
> +}
> +
> static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
> int fd, irq_handler_t handler)
> {
> @@ -186,6 +208,7 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
>
> if (irq->trigger) {
> free_irq(irq->hwirq, irq);
> + irq_bypass_unregister_producer(&irq->producer);
> kfree(irq->name);
> eventfd_ctx_put(irq->trigger);
> irq->trigger = NULL;
> @@ -216,6 +239,15 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
> return ret;
> }
>
> + irq->producer.token = (void *)trigger;
> + irq->producer.irq = irq->hwirq;
> + irq->producer.add_consumer = vfio_platform_irq_bypass_add_consumer;
> + irq->producer.del_consumer = vfio_platform_irq_bypass_del_consumer;
> + irq->producer.stop = vfio_platform_irq_bypass_stop;
> + irq->producer.start = vfio_platform_irq_bypass_start;
> + ret = irq_bypass_register_producer(&irq->producer);
> + WARN_ON(ret);

For what purpose?

> +
> if (!irq->masked)
> enable_irq(irq->hwirq);
>
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 1c9b3d5..1d2d4d6 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -17,6 +17,7 @@
>
> #include <linux/types.h>
> #include <linux/interrupt.h>
> +#include <linux/irqbypass.h>
>
> #define VFIO_PLATFORM_OFFSET_SHIFT 40
> #define VFIO_PLATFORM_OFFSET_MASK (((u64)(1) << VFIO_PLATFORM_OFFSET_SHIFT) - 1)
> @@ -37,6 +38,7 @@ struct vfio_platform_irq {
> spinlock_t lock;
> struct virqfd *unmask;
> struct virqfd *mask;
> + struct irq_bypass_producer producer;
> };
>
> struct vfio_platform_region {



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