[patch 27/30] xen/events: Only force affinity mask for percpu interrupts

[boris.ostrovsky at oracle.com]

On 12/10/20 2:26 PM, Thomas Gleixner wrote:
> All event channel setups bind the interrupt on CPU0 or the target CPU for
> percpu interrupts and overwrite the affinity mask with the corresponding
> cpumask. That does not make sense.
>
> The XEN implementation of irqchip::irq_set_affinity() already picks a
> single target CPU out of the affinity mask and the actual target is stored
> in the effective CPU mask, so destroying the user chosen affinity mask
> which might contain more than one CPU is wrong.
>
> Change the implementation so that the channel is bound to CPU0 at the XEN
> level and leave the affinity mask alone. At startup of the interrupt
> affinity will be assigned out of the affinity mask and the XEN binding will
> be updated. 


If that's the case then I wonder whether we need this call at all and instead bind at startup time.


-boris


> Only keep the enforcement for real percpu interrupts.