Soby Mathew 203cdfe26f Fix PSCI CPU ON race when setting state to ON_PENDING ... When a CPU is powered down using PSCI CPU OFF API, it disables its caches and updates its `aff_info_state` to OFF. The corresponding cache line is invalidated by the CPU so that the update will be observed by other CPUs running with caches enabled. There is a possibility that another CPU which has been trying to turn ON this CPU via PSCI CPU ON API, has already seen the update to `aff_info_state` and proceeds to update the state to ON_PENDING prior to the cache invalidation. This may result in the update of the state to ON_PENDING being discarded. This patch fixes this issue by making sure that the update of `aff_info_state` to ON_PENDING sticks by reading back the value after the cache flush and retrying it if not updated. The patch also adds a dsbish() to `psci_do_cpu_off()` to ensure ordering of the update to `aff_info_state` prior to cache line invalidation. Fixes ARM-software/tf-issues#349 Change-Id: I225de99957fe89871f8c57bcfc243956e805dcca		2016-02-01 14:52:30 +00:00
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spd	Miscellaneous doc fixes for v1.2	2015-12-21 18:10:12 +00:00
std_svc	Fix PSCI CPU ON race when setting state to ON_PENDING	2016-02-01 14:52:30 +00:00