[PATCH v2 4/5] powerpc: Define config option for processors with broadcast TLBIE

[Paul Mackerras]

Power ISA v3.0 (and later) implementations in the Linux Compliancy
Subset and lower are not required to implement broadcast TLBIE, and in
fact Microwatt doesn't.

To avoid the need to specify "disable_tlbie" on the kernel command
line on SMP Microwatt systems, this defines a config option that
asserts that the platform implements broadcast TLBIE.  This option is
selected by the pseries and powernv platforms, but not by microwatt.
Note that this option is only relevant when the radix MMU is being
used, so platforms without a radix MMU don't need it.

Signed-off-by: Paul Mackerras <paulus at ozlabs.org>
---
v2: Made the option positive (has broadcast) rather than negative

 arch/powerpc/mm/book3s64/pgtable.c     |  4 ++--
 arch/powerpc/platforms/Kconfig.cputype | 13 +++++++++++++
 arch/powerpc/platforms/powernv/Kconfig |  1 +
 arch/powerpc/platforms/pseries/Kconfig |  1 +
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 374542528080..da0bba29a9d7 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -591,7 +591,7 @@ int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
 /*
  * Does the CPU support tlbie?
  */
-bool tlbie_capable __read_mostly = true;
+bool tlbie_capable __read_mostly = IS_ENABLED(CONFIG_PPC_RADIX_BROADCAST_TLBIE);
 EXPORT_SYMBOL(tlbie_capable);
 
 /*
@@ -599,7 +599,7 @@ EXPORT_SYMBOL(tlbie_capable);
  * address spaces? tlbie may still be used for nMMU accelerators, and for KVM
  * guest address spaces.
  */
-bool tlbie_enabled __read_mostly = true;
+bool tlbie_enabled __read_mostly = IS_ENABLED(CONFIG_PPC_RADIX_BROADCAST_TLBIE);
 
 static int __init setup_disable_tlbie(char *str)
 {
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 1453ccc900c4..613b383ed8b3 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -449,6 +449,19 @@ config PPC_RADIX_MMU_DEFAULT
 
 	  If you're unsure, say Y.
 
+config PPC_RADIX_BROADCAST_TLBIE
+	bool
+	depends on PPC_RADIX_MMU
+	help
+	  Power ISA v3.0 and later implementations in the Linux Compliancy Subset
+	  and lower are not required to implement broadcast TLBIE instructions.
+	  Platforms with CPUs that do implement TLBIE broadcast, that is, where
+	  a TLB invalidation instruction performed on one CPU operates on the
+	  TLBs of all CPUs in the system, should select this option.  If this
+	  option is selected, the disable_tlbie kernel command line option can
+	  be used to cause global TLB invalidations to be done via IPIs; without
+	  it, IPIs will be used unconditionally.
+
 config PPC_KERNEL_PREFIXED
 	depends on PPC_HAVE_PREFIXED_SUPPORT
 	depends on CC_HAS_PREFIXED
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index 70a46acc70d6..3fbe0295ce14 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -17,6 +17,7 @@ config PPC_POWERNV
 	select MMU_NOTIFIER
 	select FORCE_SMP
 	select ARCH_SUPPORTS_PER_VMA_LOCK
+	select PPC_RADIX_BROADCAST_TLBIE
 	default y
 
 config OPAL_PRD
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index 42fc66e97539..206dfa0a3b33 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -23,6 +23,7 @@ config PPC_PSERIES
 	select FORCE_SMP
 	select SWIOTLB
 	select ARCH_SUPPORTS_PER_VMA_LOCK
+	select PPC_RADIX_BROADCAST_TLBIE
 	default y
 
 config PARAVIRT
-- 
2.47.1