arm64: acpi: Harden get_cpu_for_acpi_id() against missing CPU entry

In a review discussion of the changes to support vCPU hotplug where
a check was added on the GICC being enabled if was online, it was
noted that there is need to map back to the cpu and use that to index
into a cpumask. As such, a valid ID is needed.

If an MPIDR check fails in acpi_map_gic_cpu_interface() it is possible
for the entry in cpu_madt_gicc[cpu] == NULL.  This function would
then cause a NULL pointer dereference.   Whilst a path to trigger
this has not been established, harden this caller against the
possibility.

Reviewed-by: Gavin Shan <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

0 files changed, 0 insertions, 0 deletions