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    SubjectRe: [PATCH v3 06/10] VFIO: platform: add irq bypass producer management
    On Mon, Aug 10, 2015 at 03:21:00PM +0200, Eric Auger wrote:
    > This patch populates the IRQ bypass callacks:
    > - stop/start producer simply consist in disabling/enabling the host irq
    > - add/del consumer: basically set the automasked flag to false/true
    >
    > Signed-off-by: Eric Auger <eric.auger@linaro.org>
    >
    > ---
    > v2 -> v3:
    > - vfio_platform_irq_bypass_add_consumer now returns an error in case
    > the IRQ is recognized as active
    > - active boolean not set anymore
    > - do not VFIO mask the IRQ anymore on unforward
    >
    > v1 -> v2:
    > - device handle caching in vfio_platform_device is introduced in a
    > separate patch
    > - use container_of
    > ---
    > drivers/vfio/platform/vfio_platform_irq.c | 23 ++++++++++++++++++++++-
    > 1 file changed, 22 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
    > index efaee58..400a188 100644
    > --- a/drivers/vfio/platform/vfio_platform_irq.c
    > +++ b/drivers/vfio/platform/vfio_platform_irq.c
    > @@ -224,23 +224,44 @@ static int vfio_platform_is_active(struct vfio_platform_irq *irq)
    >
    > static void vfio_platform_irq_bypass_stop(struct irq_bypass_producer *prod)
    > {
    > + disable_irq(prod->irq);
    > }
    >
    > static void vfio_platform_irq_bypass_start(struct irq_bypass_producer *prod)
    > {
    > + enable_irq(prod->irq);
    > }
    >
    > static int vfio_platform_irq_bypass_add_consumer(
    > struct irq_bypass_producer *prod,
    > struct irq_bypass_consumer *cons)
    > {
    > - return 0;
    > + struct vfio_platform_irq *irq =
    > + container_of(prod, struct vfio_platform_irq, producer);
    > +
    > + /*
    > + * if the IRQ is active at irqchip level or VFIO (auto)masked
    If masked by VFIO?
    > + * this means the host IRQ is already under injection in the
    > + * guest and this not safe to change the forwarding state at
    > + * that stage.

    is this really specifically bound to guests?

    > + * It is not possible to differentiate user-space masking
    > + * from auto-masking, leading to possible false detection of
    > + * active state.

    ok, what is the consequence of that?

    > + */
    > + if (vfio_platform_is_active(irq))
    > + return -EAGAIN;
    > +
    > + return vfio_platform_set_automasked(irq, false);
    > }
    >
    > static void vfio_platform_irq_bypass_del_consumer(
    > struct irq_bypass_producer *prod,
    > struct irq_bypass_consumer *cons)
    > {
    > + struct vfio_platform_irq *irq =
    > + container_of(prod, struct vfio_platform_irq, producer);
    > +
    > + vfio_platform_set_automasked(irq, true);
    > }
    >
    > static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
    > --
    > 1.9.1
    >


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