[PATCH] powerpc/xics: Adjust interrupt receive priority for offline cpus

[Balbir Singh]

On Thu, Feb 23, 2017 at 9:54 PM, Vaidyanathan Srinivasan
<svaidy at linux.vnet.ibm.com> wrote:
> Offline CPUs need to receive IPIs through XIVE when they are
> in stop state and wakeup from that state.
>
> Reduce interrupt receive priority in order to receive XIVE
> wakeup interrupts when in offline state.
>
> LOWEST_PRIORITY would allow all interrupts to be delivered
> as wakeup events.
>
> Signed-off-by: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
> ---
>  arch/powerpc/sysdev/xics/xics-common.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c
> index 69d858e..c674a9d 100644
> --- a/arch/powerpc/sysdev/xics/xics-common.c
> +++ b/arch/powerpc/sysdev/xics/xics-common.c
> @@ -199,7 +199,7 @@ void xics_migrate_irqs_away(void)
>         xics_set_cpu_giq(xics_default_distrib_server, 0);
>
>         /* Allow IPIs again... */
> -       icp_ops->set_priority(DEFAULT_PRIORITY);
> +       icp_ops->set_priority(LOWEST_PRIORITY);
>

Aren't IPI's at higher priority than DEFAULT_PRIORITY? Like Mikey said
I am not sure what
is broken with the current implementation? Is this true for all
icp_ops? I presume you are using
icp_opal. I suspect you'll need to look at

1. XIVE to see if EMULATION_PRIO is the issue
2. Check if only icp_opal is impacted

Balbir Singh.