[PATCH 1/4] powerpc/xive: Use XIVE_BAD_IRQ instead of zero to catch non configured IPIs

[Michael Ellerman]

On Fri, 2020-03-06 at 15:01:40 UTC, =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= wrote:
> When a CPU is brought up, an IPI number is allocated and recorded
> under the XIVE CPU structure. Invalid IPI numbers are tracked with
> interrupt number 0x0.
> 
> On the PowerNV platform, the interrupt number space starts at 0x10 and
> this works fine. However, on the sPAPR platform, it is possible to
> allocate the interrupt number 0x0 and this raises an issue when CPU 0
> is unplugged. The XIVE spapr driver tracks allocated interrupt numbers
> in a bitmask and it is not correctly updated when interrupt number 0x0
> is freed. It stays allocated and it is then impossible to reallocate.
> 
> Fix by using the XIVE_BAD_IRQ value instead of zero on both platforms.
> 
> Reported-by: David Gibson <david at gibson.dropbear.id.au>
> Fixes: eac1e731b59e ("powerpc/xive: guest exploitation of the XIVE interrupt controller")
> Cc: stable at vger.kernel.org # v4.14+
> Signed-off-by: Cédric Le Goater <clg at kaod.org>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/b1a504a6500df50e83b701b7946b34fce27ad8a3

cheers