[PATCH V2 07/14] arm64/mm: Enable pgtable geometry for FEAT_D128
From: Anshuman Khandual <hidden>
Date: 2026-09-07 03:51:26
Also in:
linux-mm, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual <redacted> --- 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 b5a51b0ef944..306e6c803471 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig@@ -284,14 +284,18 @@ 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
@@ -362,6 +366,16 @@ 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)
@@ -1594,7 +1608,7 @@ 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"
@@ -2289,6 +2303,19 @@ 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 7a5d6a14bb52..4b534be3f288 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h@@ -1075,6 +1075,8 @@ 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