Re: [PATCH 4/9] xen: Add support to check if IRQ line is shared with other domains.

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 12/13/2010 10:01 AM, Konrad Rzeszutek Wilk wrote:
> We do this via the PHYSDEVOP_irq_status_query support hypervisor call.
> We will get a positive value if another domain has binded its
> PIRQ to the specified IRQ line.
>
> [v2: Deal with v2.6.37-rc1 rebase fallout]
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  drivers/xen/events.c |   13 +++++++++++++
>  include/xen/events.h |    3 +++
>  2 files changed, 16 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index 96c93e7..690dfad 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -1398,6 +1398,19 @@ void xen_poll_irq(int irq)
>  	xen_poll_irq_timeout(irq, 0 /* no timeout */);
>  }
>  
> +/* Check whether the IRQ line is shared with other guests. */
> +int xen_ignore_irq(int irq)

I think this could do with a better name.  The function actually testing
for sharing; the fact you might choose to ignore it because its shared
is by the by (and becomes very misleading if you end up wanting to test
for sharedness for some other reason).

> +{
> +	struct irq_info *info = info_for_irq(irq);
> +	struct physdev_irq_status_query irq_status = { .irq =
> +							info->u.pirq.gsi };

That's a pretty awkward linebreak.

    J

> +
> +	if (HYPERVISOR_physdev_op(PHYSDEVOP_irq_status_query, &irq_status))
> +		return 0;
> +	return !(irq_status.flags & XENIRQSTAT_shared);
> +}
> +EXPORT_SYMBOL_GPL(xen_ignore_irq);
> +
>  void xen_irq_resume(void)
>  {
>  	unsigned int cpu, irq, evtchn;
> diff --git a/include/xen/events.h b/include/xen/events.h
> index 646dd17..553c664 100644
> --- a/include/xen/events.h
> +++ b/include/xen/events.h
> @@ -89,4 +89,7 @@ int xen_vector_from_irq(unsigned pirq);
>  /* Return gsi allocated to pirq */
>  int xen_gsi_from_irq(unsigned pirq);
>  
> +/* Determine whether to ignore this IRQ if passed to a guest. */
> +int xen_ignore_irq(int irq);
> +
>  #endif	/* _XEN_EVENTS_H */