powerpc: Define config option for processors with broadcast TLBIE

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@ozlabs.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/Z5xtvdozEfEmRyeI@thinks.paulus.ozlabs.org

Author: paulusmack

arch/powerpc/mm/book3s64/pgtable.c

@@ -587,15 +587,15 @@ 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);
 
 /*
  * Should tlbie be used for management of CPU TLBs, for kernel and process
  * 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)
 {

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

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

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