[PATCH 12/17] arm64/mm: Enable pgtable geometry for FEAT_D128

[Anshuman Khandual]

Add build time support for FEAT_D128 page tables with a new Kconfig option
i.e CONFIG_ARM64_D128. When selected, PTE types become 128 bits wide and
PTE bits are mapped to their new locations. Besides the basic page table
geometry is also updated since each table page now holds half the number
of entries (aka PTRS_PER_PXX) as it did previously. Similarly update the
geometry relevant macros ARM64_CONT_[PTE|PMD]_SHIFT, PGTABLE_LEVELS, and
PTDESC_ORDER.

Although for now config ARM64_D128 remains disabled while all the required
dependencies are getting created in subsequent patches.

Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Ryan Roberts <ryan.roberts at arm.com>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-kernel at vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
---
 arch/arm64/Kconfig                     | 37 ++++++++++++++++++++++----
 arch/arm64/include/asm/pgtable-hwdef.h |  4 +++
 arch/arm64/include/asm/pgtable.h       |  2 ++
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b3afe0688919..8459d43afd45 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -283,14 +283,18 @@ config MMU
 
 config ARM64_CONT_PTE_SHIFT
 	int
-	default 5 if PAGE_SIZE_64KB
-	default 7 if PAGE_SIZE_16KB
+	default 4 if PAGE_SIZE_64KB && ARM64_D128
+	default 5 if PAGE_SIZE_64KB && !ARM64_D128
+	default 6 if PAGE_SIZE_16KB && ARM64_D128
+	default 7 if PAGE_SIZE_16KB && !ARM64_D128
 	default 4
 
 config ARM64_CONT_PMD_SHIFT
 	int
-	default 5 if PAGE_SIZE_64KB
-	default 5 if PAGE_SIZE_16KB
+	default 6 if PAGE_SIZE_64KB && ARM64_D128
+	default 5 if PAGE_SIZE_64KB && !ARM64_D128
+	default 4 if PAGE_SIZE_16KB && ARM64_D128
+	default 5 if PAGE_SIZE_16KB && !ARM64_D128
 	default 4
 
 config ARCH_MMAP_RND_BITS_MIN
@@ -361,6 +365,16 @@ config FIX_EARLYCON_MEM
 
 config PGTABLE_LEVELS
 	int
+	default 4 if ARM64_D128 && ARM64_4K_PAGES && ARM64_VA_BITS_39
+	default 5 if ARM64_D128 && ARM64_4K_PAGES && ARM64_VA_BITS_48
+	default 5 if ARM64_D128 && ARM64_4K_PAGES && ARM64_VA_BITS_52
+	default 3 if ARM64_D128 && ARM64_16K_PAGES && ARM64_VA_BITS_36
+	default 4 if ARM64_D128 && ARM64_16K_PAGES && ARM64_VA_BITS_47
+	default 4 if ARM64_D128 && ARM64_16K_PAGES && ARM64_VA_BITS_48
+	default 4 if ARM64_D128 && ARM64_16K_PAGES && ARM64_VA_BITS_52
+	default 3 if ARM64_D128 && ARM64_64K_PAGES && ARM64_VA_BITS_42
+	default 3 if ARM64_D128 && ARM64_64K_PAGES && ARM64_VA_BITS_48
+	default 3 if ARM64_D128 && ARM64_64K_PAGES && ARM64_VA_BITS_52
 	default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
 	default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42
 	default 3 if ARM64_64K_PAGES && (ARM64_VA_BITS_48 || ARM64_VA_BITS_52)
@@ -1540,7 +1554,7 @@ config ARM64_PA_BITS
 
 config ARM64_LPA2
 	def_bool y
-	depends on ARM64_PA_BITS_52 && !ARM64_64K_PAGES
+	depends on ARM64_PA_BITS_52 && !ARM64_64K_PAGES && !ARM64_D128
 
 choice
 	prompt "Endianness"
@@ -2233,6 +2247,19 @@ config ARM64_HAFT
 
 endmenu # "ARMv8.9 architectural features"
 
+menu "ARMv9.3 architectural features"
+
+config ARM64_D128
+	bool
+	default n
+	help
+	  ARMv9.3 introduces FEAT_D128, which provides a 128 bit page
+	  table format, along with related instructions.
+
+	  If unsure, say Y.
+
+endmenu # "ARMv9.3 architectural features"
+
 menu "ARMv9.4 architectural features"
 
 config ARM64_GCS
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 72f31800c703..1ee1a6d9db6d 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -7,7 +7,11 @@
 
 #include <asm/memory.h>
 
+#ifdef CONFIG_ARM64_D128
+#define PTDESC_ORDER 4
+#else
 #define PTDESC_ORDER 3
+#endif
 
 /* Number of VA bits resolved by a single translation table level */
 #define PTDESC_TABLE_SHIFT	(PAGE_SHIFT - PTDESC_ORDER)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 50d673474f47..ed5ea7d31c0a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1128,6 +1128,8 @@ static inline bool pgtable_l4_enabled(void) { return false; }
 
 static __always_inline bool pgtable_l5_enabled(void)
 {
+	if (IS_ENABLED(CONFIG_ARM64_D128))
+		return true;
 	if (!alternative_has_cap_likely(ARM64_ALWAYS_BOOT))
 		return vabits_actual == VA_BITS;
 	return alternative_has_cap_unlikely(ARM64_HAS_VA52);
-- 
2.43.0