On Mon, Aug 10, 2020 at 08:11:43PM +0000, Frank van der Linden wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> commit baedb87d1b53532f81b4bd0387f83b05d4f7eb9a upstream.
>
> Setting interrupt affinity on inactive interrupts is inconsistent when
> hierarchical irq domains are enabled. The core code should just store the
> affinity and not call into the irq chip driver for inactive interrupts
> because the chip drivers may not be in a state to handle such requests.
>
> X86 has a hacky workaround for that but all other irq chips have not which
> causes problems e.g. on GIC V3 ITS.
>
> Instead of adding more ugly hacks all over the place, solve the problem in
> the core code. If the affinity is set on an inactive interrupt then:
>
> - Store it in the irq descriptors affinity mask
> - Update the effective affinity to reflect that so user space has
> a consistent view
> - Don't call into the irq chip driver
>
> This is the core equivalent of the X86 workaround and works correctly
> because the affinity setting is established in the irq chip when the
> interrupt is activated later on.
>
> Note, that this is only effective when hierarchical irq domains are enabled
> by the architecture. Doing it unconditionally would break legacy irq chip
> implementations.
>
> For hierarchial irq domains this works correctly as none of the drivers can
> have a dependency on affinity setting in inactive state by design.
>
> Remove the X86 workaround as it is not longer required.
>
> Fixes: 02edee152d6e ("x86/apic/vector: Ignore set_affinity call for inactive interrupts")
Why is this needed for 4.14.y, when this "Fixes:" tag says a commit that
showed up in 4.15?
thanks,
greg k-h
