KVM: PPC: Book3S HV: Add missing barriers to XIVE code and document them
authorBenjamin Herrenschmidt <benh@kernel.crashing.org>
Fri, 18 Aug 2017 02:10:58 +0000 (12:10 +1000)
committerPaul Mackerras <paulus@ozlabs.org>
Thu, 24 Aug 2017 10:02:01 +0000 (20:02 +1000)
commitbb9b52bd51dcb17b965a30167d0812902c1b9927
tree95d4860f9d51e445ac460c20264d6c1e43e87c9e
parent2c4fb78f78b6e420604ee1b05bdfb5c1d637869f
KVM: PPC: Book3S HV: Add missing barriers to XIVE code and document them

This adds missing memory barriers to order updates/tests of
the virtual CPPR and MFRR, thus fixing a lost IPI problem.

While at it also document all barriers in this file.

This fixes a bug causing guest IPIs to occasionally get lost.  The
symptom then is hangs or stalls in the guest.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
arch/powerpc/kvm/book3s_xive_template.c