Subject: [RFC PATCH v2 2/5] powerpc/pmem: Disable synchronous fault by default

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 2 Jun 2020 13:19:06 +0530

This adds a kernel config option that controls whether MAP_SYNC is enabled by
default. With POWER10, architecture is adding new pmem flush and sync
instructions. The kernel should prevent the usage of MAP_SYNC if applications
are not using the new instructions on newer hardware.

This config allows user to control whether MAP_SYNC should be enabled by
default or not.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---
 arch/powerpc/platforms/Kconfig.cputype | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 27a81c291be8..f8694838ad4e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -383,6 +383,15 @@ config PPC_KUEP
 
 	  If you're unsure, say Y.
 
+config ARCH_MAP_SYNC_DISABLE
+	bool "Disable synchronous fault support (MAP_SYNC)"
+	default y
+	help
+	  Disable support for synchronous fault with nvdimm namespaces.
+
+	  If you're unsure, say Y.
+
+
 config PPC_HAVE_KUAP
 	bool
 
-- 
2.26.2