[PATCH] powerpc/xive: discard ESB load value when interrupt is invalid

[Michael Ellerman]

Cédric Le Goater <clg at kaod.org> writes:
> On 1/13/20 2:01 PM, Cédric Le Goater wrote:
>> From: Frederic Barrat <fbarrat at linux.ibm.com>
>> 
>> A load on an ESB page returning all 1's means that the underlying
>> device has invalidated the access to the PQ state of the interrupt
>> through mmio. It may happen, for example when querying a PHB interrupt
>> while the PHB is in an error state.
>> 
>> In that case, we should consider the interrupt to be invalid when
>> checking its state in the irq_get_irqchip_state() handler.
>
>
> and we need also these tags :
>
> Fixes: da15c03b047d ("powerpc/xive: Implement get_irqchip_state method for XIVE to fix shutdown race")
> Cc: stable at vger.kernel.org # v5.3+

I added those, although it's v5.4+, as the offending commit was first
included in v5.4-rc1.

cheers