powerpc/xive: Use XIVE_BAD_IRQ instead of zero to catch non configured IPIs
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@gibson.dropbear.id.au> Fixes: eac1e731 ("powerpc/xive: guest exploitation of the XIVE interrupt controller") Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Cédric Le Goater <clg@kaod.org> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Tested-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200306150143.5551-2-clg@kaod.org
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