Re: [Qemu-devel] [PATCH v2 4/8] spapr: Move interrupt allocator to xics

[Alexander Graf <agraf@suse.de>]

On 15.05.14 11:59, Alexey Kardashevskiy wrote:
> The current allocator returns IRQ numbers from a pool and does not
> support IRQs reuse in any form as it did not keep track of what it
> previously returned, it only keeps the last returned IRQ. Some use
> cases such as PCI hot(un)plug may require IRQ release and reallocation.
>
> This moves an allocator from SPAPR to XICS.
>
> This switches IRQ users to use new API.
>
> This uses LSI/MSI flags to know if interrupt is allocated.
>
> The interrupt release function will be posted as a separate patch.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>   hw/intc/xics.c         | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   hw/ppc/spapr.c         | 67 --------------------------------------
>   hw/ppc/spapr_events.c  |  2 +-
>   hw/ppc/spapr_pci.c     |  6 ++--
>   hw/ppc/spapr_vio.c     |  2 +-
>   include/hw/ppc/spapr.h | 10 ------
>   include/hw/ppc/xics.h  |  2 ++
>   trace-events           |  4 +++
>   8 files changed, 99 insertions(+), 82 deletions(-)
>
> diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> index 83a809e..fdcbb3a 100644
> --- a/hw/intc/xics.c
> +++ b/hw/intc/xics.c
> @@ -689,6 +689,94 @@ void xics_set_irq_type(XICSState *icp, int irq, bool lsi)
>       ics_set_irq_type(ics, irq - ics->offset, lsi);
>   }
>   
> +#define ICS_IRQ_FREE(ics, srcno)   \
> +    (!((ics)->irqs[(srcno)].flags & (XICS_FLAGS_IRQ_MASK)))
> +
> +static int ics_find_free_block(ICSState *ics, int num, int alignnum)
> +{
> +    int first, i;
> +
> +    for (first = 0; first < ics->nr_irqs; first += alignnum) {
> +        if (num > (ics->nr_irqs - first)) {
> +            return -1;
> +        }
> +        for (i = first; i < first + num; ++i) {
> +            if (!ICS_IRQ_FREE(ics, i)) {
> +                break;
> +            }
> +        }
> +        if (i == (first + num)) {
> +            return first;
> +        }
> +    }
> +
> +    return -1;
> +}
> +
> +int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi)
> +{
> +    ICSState *ics = &icp->ics[src];
> +    int irq;
> +
> +    if (irq_hint) {
> +        assert(src == xics_find_source(icp, irq_hint));

Could this ever get triggered by a guest? Why don't we just fail as if 
the IRQ wasn't available?


Alex