Add documentation of l1d flushing, explain the need for the
feature and how it can be used.
Signed-off-by: NBalbir Singh <sblbir@amazon.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210108121056.21940-6-sblbir@amazon.com