[PATCH 4/5] powerpc: Define config option for processors without broadcast TLBIE

[Paul Mackerras]

Power ISA v3.1 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 broadcast TLBIE should never be used
(the kernel will instead use IPIs to trigger local TLBIEs on other
CPUs when required).

Signed-off-by: Paul Mackerras <paulus at ozlabs.org>
---
 arch/powerpc/mm/book3s64/pgtable.c       | 10 ++++++++--
 arch/powerpc/platforms/Kconfig.cputype   | 12 ++++++++++++
 arch/powerpc/platforms/microwatt/Kconfig |  1 +
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 374542528080..14ee96e2a581 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -588,10 +588,16 @@ int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
 }
 #endif
 
+#ifndef CONFIG_PPC_RADIX_NO_BROADCAST_TLBIE
+#define DEFAULT_TLBIE_ENABLE	true
+#else
+#define DEFAULT_TLBIE_ENABLE	false
+#endif
+
 /*
  * Does the CPU support tlbie?
  */
-bool tlbie_capable __read_mostly = true;
+bool tlbie_capable __read_mostly = DEFAULT_TLBIE_ENABLE;
 EXPORT_SYMBOL(tlbie_capable);
 
 /*
@@ -599,7 +605,7 @@ 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 = DEFAULT_TLBIE_ENABLE;
 
 static int __init setup_disable_tlbie(char *str)
 {
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 1453ccc900c4..bd2a4e46ab34 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -449,6 +449,18 @@ config PPC_RADIX_MMU_DEFAULT
 
 	  If you're unsure, say Y.
 
+config PPC_RADIX_NO_BROADCAST_TLBIE
+	depends on PPC_RADIX_MMU
+	help
+	  Power ISA v3.1 implementations in the Linux Compliancy Subset
+	  and lower are not required to implement broadcast TLBIE
+	  instructions, that is, a TLB invalidation instruction
+	  performed on one CPU is not required to operate on the TLBs
+	  in all CPUs in the system.  Instead, the kernel does an IPI
+	  to each relevant CPU to get it to do a local TLBIE instruction.
+	  Select this option to force global invalidations to be done via
+	  IPIs unconditionally.
+
 config PPC_KERNEL_PREFIXED
 	depends on PPC_HAVE_PREFIXED_SUPPORT
 	depends on CC_HAS_PREFIXED
diff --git a/arch/powerpc/platforms/microwatt/Kconfig b/arch/powerpc/platforms/microwatt/Kconfig
index 5e41adadac1f..1d5cc1ae3636 100644
--- a/arch/powerpc/platforms/microwatt/Kconfig
+++ b/arch/powerpc/platforms/microwatt/Kconfig
@@ -7,6 +7,7 @@ config PPC_MICROWATT
 	select PPC_ICP_NATIVE
 	select PPC_UDBG_16550
 	select COMMON_CLK
+	select PPC_RADIX_NO_BROADCAST_TLBIE
 	help
           This option enables support for FPGA-based Microwatt implementations.
 
-- 
2.47.1