powerpc/64s: Make hash MMU support configurable

This adds Kconfig selection which allows 64s hash MMU support to be
disabled. It can be disabled if radix support is enabled, the minimum
supported CPU type is POWER9 (or higher), and KVM is not selected.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-17-npiggin@gmail.com

arch/powerpc/Kconfig

@@ -846,7 +846,7 @@ config FORCE_MAX_ZONEORDER
 config PPC_SUBPAGE_PROT
 	bool "Support setting protections for 4k subpages (subpage_prot syscall)"
 	default n
-	depends on PPC_BOOK3S_64 && PPC_64K_PAGES
+	depends on PPC_64S_HASH_MMU && PPC_64K_PAGES
 	help
 	  This option adds support for system call to allow user programs
 	  to set access permissions (read/write, readonly, or no access)
@@ -944,6 +944,7 @@ config PPC_MEM_KEYS
 	prompt "PowerPC Memory Protection Keys"
 	def_bool y
 	depends on PPC_BOOK3S_64
+	depends on PPC_64S_HASH_MMU
 	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_HAS_PKEYS
 	help

arch/powerpc/include/asm/mmu.h

@@ -157,7 +157,7 @@ DECLARE_PER_CPU(int, next_tlbcam_idx);
 
 enum {
 	MMU_FTRS_POSSIBLE =
-#if defined(CONFIG_PPC_BOOK3S_64) || defined(CONFIG_PPC_BOOK3S_604)
+#if defined(CONFIG_PPC_BOOK3S_604)
 		MMU_FTR_HPTE_TABLE |
 #endif
 #ifdef CONFIG_PPC_8xx
@@ -184,15 +184,18 @@ enum {
 		MMU_FTR_USE_TLBRSRV | MMU_FTR_USE_PAIRED_MAS |
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64
+		MMU_FTR_KERNEL_RO |
+#ifdef CONFIG_PPC_64S_HASH_MMU
 		MMU_FTR_NO_SLBIE_B | MMU_FTR_16M_PAGE | MMU_FTR_TLBIEL |
 		MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_CI_LARGE_PAGE |
 		MMU_FTR_1T_SEGMENT | MMU_FTR_TLBIE_CROP_VA |
-		MMU_FTR_KERNEL_RO | MMU_FTR_68_BIT_VA |
+		MMU_FTR_68_BIT_VA | MMU_FTR_HPTE_TABLE |
 #endif
 #ifdef CONFIG_PPC_RADIX_MMU
 		MMU_FTR_TYPE_RADIX |
 		MMU_FTR_GTSE |
 #endif /* CONFIG_PPC_RADIX_MMU */
+#endif
 #ifdef CONFIG_PPC_KUAP
 	MMU_FTR_BOOK3S_KUAP |
 #endif /* CONFIG_PPC_KUAP */
@@ -224,6 +227,13 @@ enum {
 #define MMU_FTRS_ALWAYS		MMU_FTR_TYPE_FSL_E
 #endif
 
+/* BOOK3S_64 options */
+#if defined(CONFIG_PPC_RADIX_MMU) && !defined(CONFIG_PPC_64S_HASH_MMU)
+#define MMU_FTRS_ALWAYS		MMU_FTR_TYPE_RADIX
+#elif !defined(CONFIG_PPC_RADIX_MMU) && defined(CONFIG_PPC_64S_HASH_MMU)
+#define MMU_FTRS_ALWAYS		MMU_FTR_HPTE_TABLE
+#endif
+
 #ifndef MMU_FTRS_ALWAYS
 #define MMU_FTRS_ALWAYS		0
 #endif
@@ -329,7 +339,7 @@ static __always_inline bool radix_enabled(void)
 	return mmu_has_feature(MMU_FTR_TYPE_RADIX);
 }
 
-static inline bool early_radix_enabled(void)
+static __always_inline bool early_radix_enabled(void)
 {
 	return early_mmu_has_feature(MMU_FTR_TYPE_RADIX);
 }

arch/powerpc/kernel/dt_cpu_ftrs.c

@@ -273,6 +273,9 @@ static int __init feat_enable_mmu_hash(struct dt_cpu_feature *f)
 {
 	u64 lpcr;
 
+	if (!IS_ENABLED(CONFIG_PPC_64S_HASH_MMU))
+		return 0;
+
 	lpcr = mfspr(SPRN_LPCR);
 	lpcr &= ~LPCR_ISL;
 
@@ -292,6 +295,9 @@ static int __init feat_enable_mmu_hash_v3(struct dt_cpu_feature *f)
 {
 	u64 lpcr;
 
+	if (!IS_ENABLED(CONFIG_PPC_64S_HASH_MMU))
+		return 0;
+
 	lpcr = mfspr(SPRN_LPCR);
 	lpcr &= ~(LPCR_ISL | LPCR_UPRT | LPCR_HR);
 	mtspr(SPRN_LPCR, lpcr);
@@ -305,15 +311,15 @@ static int __init feat_enable_mmu_hash_v3(struct dt_cpu_feature *f)
 
 static int __init feat_enable_mmu_radix(struct dt_cpu_feature *f)
 {
-#ifdef CONFIG_PPC_RADIX_MMU
+	if (!IS_ENABLED(CONFIG_PPC_RADIX_MMU))
+		return 0;
+
+	cur_cpu_spec->mmu_features |= MMU_FTR_KERNEL_RO;
 	cur_cpu_spec->mmu_features |= MMU_FTR_TYPE_RADIX;
-	cur_cpu_spec->mmu_features |= MMU_FTRS_HASH_BASE;
 	cur_cpu_spec->mmu_features |= MMU_FTR_GTSE;
 	cur_cpu_spec->cpu_user_features |= PPC_FEATURE_HAS_MMU;
 
 	return 1;
-#endif
-	return 0;
 }
 
 static int __init feat_enable_dscr(struct dt_cpu_feature *f)

arch/powerpc/kvm/Kconfig

@@ -69,6 +69,7 @@ config KVM_BOOK3S_64
 	select KVM_BOOK3S_64_HANDLER
 	select KVM
 	select KVM_BOOK3S_PR_POSSIBLE if !KVM_BOOK3S_HV_POSSIBLE
+	select PPC_64S_HASH_MMU
 	select SPAPR_TCE_IOMMU if IOMMU_SUPPORT && (PPC_PSERIES || PPC_POWERNV)
 	help
 	  Support running unmodified book3s_64 and book3s_32 guest kernels

arch/powerpc/mm/init_64.c

@@ -472,8 +472,12 @@ void __init mmu_early_init_devtree(void)
 	bool hvmode = !!(mfmsr() & MSR_HV);
 
 	/* Disable radix mode based on kernel command line. */
-	if (disable_radix)
+	if (disable_radix) {
+		if (IS_ENABLED(CONFIG_PPC_64S_HASH_MMU))
 			cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
+		else
+			pr_warn("WARNING: Ignoring cmdline option disable_radix\n");
+	}
 
 	of_scan_flat_dt(dt_scan_mmu_pid_width, NULL);
 	if (hvmode && !mmu_lpid_bits) {
@@ -498,6 +502,7 @@ void __init mmu_early_init_devtree(void)
 
 	if (early_radix_enabled()) {
 		radix__early_init_devtree();
+
 		/*
 		 * We have finalized the translation we are going to use by now.
 		 * Radix mode is not limited by RMA / VRMA addressing.
@@ -507,5 +512,9 @@ void __init mmu_early_init_devtree(void)
 		memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
 	} else
 		hash__early_init_devtree();
+
+	if (!(cur_cpu_spec->mmu_features & MMU_FTR_HPTE_TABLE) &&
+	    !(cur_cpu_spec->mmu_features & MMU_FTR_TYPE_RADIX))
+		panic("kernel does not support any MMU type offered by platform");
 }
 #endif /* CONFIG_PPC_BOOK3S_64 */

arch/powerpc/platforms/Kconfig.cputype

@@ -105,9 +105,9 @@ config PPC_BOOK3S_64
 	select HAVE_MOVE_PMD
 	select HAVE_MOVE_PUD
 	select IRQ_WORK
-	select PPC_MM_SLICES
 	select PPC_HAVE_KUEP
 	select PPC_HAVE_KUAP
+	select PPC_64S_HASH_MMU if !PPC_RADIX_MMU
 
 config PPC_BOOK3E_64
 	bool "Embedded processors"
@@ -130,11 +130,13 @@ choice
 config GENERIC_CPU
 	bool "Generic (POWER4 and above)"
 	depends on PPC64 && !CPU_LITTLE_ENDIAN
+	select PPC_64S_HASH_MMU if PPC_BOOK3S_64
 
 config GENERIC_CPU
 	bool "Generic (POWER8 and above)"
 	depends on PPC64 && CPU_LITTLE_ENDIAN
 	select ARCH_HAS_FAST_MULTIPLIER
+	select PPC_64S_HASH_MMU
 
 config GENERIC_CPU
 	bool "Generic 32 bits powerpc"
@@ -143,24 +145,29 @@ config GENERIC_CPU
 config CELL_CPU
 	bool "Cell Broadband Engine"
 	depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN
+	select PPC_64S_HASH_MMU
 
 config POWER5_CPU
 	bool "POWER5"
 	depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN
+	select PPC_64S_HASH_MMU
 
 config POWER6_CPU
 	bool "POWER6"
 	depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN
+	select PPC_64S_HASH_MMU
 
 config POWER7_CPU
 	bool "POWER7"
 	depends on PPC_BOOK3S_64
 	select ARCH_HAS_FAST_MULTIPLIER
+	select PPC_64S_HASH_MMU
 
 config POWER8_CPU
 	bool "POWER8"
 	depends on PPC_BOOK3S_64
 	select ARCH_HAS_FAST_MULTIPLIER
+	select PPC_64S_HASH_MMU
 
 config POWER9_CPU
 	bool "POWER9"
@@ -364,6 +371,22 @@ config SPE
 
 	  If in doubt, say Y here.
 
+config PPC_64S_HASH_MMU
+	bool "Hash MMU Support"
+	depends on PPC_BOOK3S_64
+	select PPC_MM_SLICES
+	default y
+	help
+	  Enable support for the Power ISA Hash style MMU. This is implemented
+	  by all IBM Power and other 64-bit Book3S CPUs before ISA v3.0. The
+	  OpenPOWER ISA does not mandate the hash MMU and some CPUs do not
+	  implement it (e.g., Microwatt).
+
+	  Note that POWER9 PowerVM platforms only support the hash
+	  MMU. From POWER10 radix is also supported by PowerVM.
+
+	  If you're unsure, say Y.
+
 config PPC_RADIX_MMU
 	bool "Radix MMU Support"
 	depends on PPC_BOOK3S_64
@@ -375,7 +398,8 @@ config PPC_RADIX_MMU
 	  you can probably disable this.
 
 config PPC_RADIX_MMU_DEFAULT
-	bool "Default to using the Radix MMU when possible"
+	bool "Default to using the Radix MMU when possible" if PPC_64S_HASH_MMU
+	depends on PPC_BOOK3S_64
 	depends on PPC_RADIX_MMU
 	default y
 	help

arch/powerpc/platforms/cell/Kconfig

 # SPDX-License-Identifier: GPL-2.0
 config PPC_CELL
+	select PPC_64S_HASH_MMU if PPC64
 	bool
 
 config PPC_CELL_COMMON

arch/powerpc/platforms/maple/Kconfig

@@ -9,6 +9,7 @@ config PPC_MAPLE
 	select GENERIC_TBSYNC
 	select PPC_UDBG_16550
 	select PPC_970_NAP
+	select PPC_64S_HASH_MMU
 	select PPC_HASH_MMU_NATIVE
 	select PPC_RTAS
 	select MMIO_NVRAM

arch/powerpc/platforms/microwatt/Kconfig

@@ -5,7 +5,7 @@ config PPC_MICROWATT
 	select PPC_XICS
 	select PPC_ICS_NATIVE
 	select PPC_ICP_NATIVE
-	select PPC_HASH_MMU_NATIVE
+	select PPC_HASH_MMU_NATIVE if PPC_64S_HASH_MMU
 	select PPC_UDBG_16550
 	select ARCH_RANDOM
 	help

arch/powerpc/platforms/pasemi/Kconfig

@@ -5,6 +5,7 @@ config PPC_PASEMI
 	select MPIC
 	select FORCE_PCI
 	select PPC_UDBG_16550
+	select PPC_64S_HASH_MMU
 	select PPC_HASH_MMU_NATIVE
 	select MPIC_BROKEN_REGREAD
 	help

arch/powerpc/platforms/powermac/Kconfig

@@ -6,6 +6,7 @@ config PPC_PMAC
 	select FORCE_PCI
 	select PPC_INDIRECT_PCI if PPC32
 	select PPC_MPC106 if PPC32
+	select PPC_64S_HASH_MMU if PPC64
 	select PPC_HASH_MMU_NATIVE
 	select ZONE_DMA if PPC32
 	default y

arch/powerpc/platforms/powernv/Kconfig

@@ -2,7 +2,7 @@
 config PPC_POWERNV
 	depends on PPC64 && PPC_BOOK3S
 	bool "IBM PowerNV (Non-Virtualized) platform support"
-	select PPC_HASH_MMU_NATIVE
+	select PPC_HASH_MMU_NATIVE if PPC_64S_HASH_MMU
 	select PPC_XICS
 	select PPC_ICP_NATIVE
 	select PPC_XIVE_NATIVE

drivers/misc/cxl/Kconfig

@@ -6,6 +6,7 @@
 config CXL_BASE
 	bool
 	select PPC_COPRO_BASE
+	select PPC_64S_HASH_MMU
 
 config CXL
 	tristate "Support for IBM Coherent Accelerators (CXL)"

drivers/misc/lkdtm/Makefile

@@ -11,7 +11,7 @@ lkdtm-$(CONFIG_LKDTM)		+= usercopy.o
 lkdtm-$(CONFIG_LKDTM)		+= stackleak.o
 lkdtm-$(CONFIG_LKDTM)		+= cfi.o
 lkdtm-$(CONFIG_LKDTM)		+= fortify.o
-lkdtm-$(CONFIG_PPC_BOOK3S_64)	+= powerpc.o
+lkdtm-$(CONFIG_PPC_64S_HASH_MMU)	+= powerpc.o
 
 KASAN_SANITIZE_rodata.o		:= n
 KASAN_SANITIZE_stackleak.o	:= n