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Commit 2ed7533c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'powerpc-4.18-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 

Pull powerpc fixes from Michael Ellerman:
 "One fix for a regression in a recent TLB flush optimisation, which
  caused us to incorrectly not send TLB invalidations to coprocessors.

  Thanks to Frederic Barrat, Nicholas Piggin, Vaibhav Jain"

* tag 'powerpc-4.18-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s/radix: Fix missing global invalidations when removing copro
parents 7827fc7d cca19f0b

arch/powerpc/include/asm/mmu_context.h

+21 −12
Original line number Diff line number Diff line
@@ -143,23 +143,32 @@ static inline void mm_context_remove_copro(struct mm_struct *mm) 
{

	int c;



	c = atomic_dec_if_positive(&mm->context.copros);



	/* Detect imbalance between add and remove */

	WARN_ON(c < 0);



	/*

	 * Need to broadcast a global flush of the full mm before

	 * decrementing active_cpus count, as the next TLBI may be

	 * local and the nMMU and/or PSL need to be cleaned up.

	 * Should be rare enough so that it's acceptable.

	 * When removing the last copro, we need to broadcast a global

	 * flush of the full mm, as the next TLBI may be local and the

	 * nMMU and/or PSL need to be cleaned up.

	 *

	 * Both the 'copros' and 'active_cpus' counts are looked at in

	 * flush_all_mm() to determine the scope (local/global) of the

	 * TLBIs, so we need to flush first before decrementing

	 * 'copros'. If this API is used by several callers for the

	 * same context, it can lead to over-flushing. It's hopefully

	 * not common enough to be a problem.

	 *

	 * Skip on hash, as we don't know how to do the proper flush

	 * for the time being. Invalidations will remain global if

	 * used on hash.

	 * used on hash. Note that we can't drop 'copros' either, as

	 * it could make some invalidations local with no flush

	 * in-between.

	 */

	if (c == 0 && radix_enabled()) {

	if (radix_enabled()) {

		flush_all_mm(mm);



		c = atomic_dec_if_positive(&mm->context.copros);

		/* Detect imbalance between add and remove */

		WARN_ON(c < 0);



		if (c == 0)

			dec_mm_active_cpus(mm);

	}

}