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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772115031; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wmxDJL7qK9NueU1uB+zhPhctO+wgXUQrbU9tvkKi3t8=; b=R0xJNFhztYNzYvCaGxImWv7FJWbrKhaXA3gG/3dDXiofF/l2Aqsq753GVna3Ij69ih27v9 KE2b1zOTW6pKbkk69d8j7WcUH9wvTKOfhGVsgGVRtZPaWLAxmwsWDKBLKVdiLGFtZRbtIj zwbQ1IFq+zo3rNI4cHabyooNLpcvT2Q= From: Usama Arif To: Anshuman Khandual Cc: Usama Arif , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , David Hildenbrand , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC V1 16/16] arm64/mm: Add initial support for FEAT_D128 page tables Date: Thu, 26 Feb 2026 06:10:23 -0800 Message-ID: <20260226141024.1869713-1-usama.arif@linux.dev> In-Reply-To: <20260224051153.3150613-17-anshuman.khandual@arm.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 3r1nbfef6dg85ri61g8ci3t6hmebh8x4 X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 6AEB0180009 X-HE-Tag: 1772115037-912346 X-HE-Meta: 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 bkTRrw7U ZF9w1omBbUqondCv5PTO1acE0bLIGtAJcFx+q6RtA7Nv11McUSdm45zxWsy7Ef2bSEXdMde4l059QpBfdo0oEGWFVHBcaJ6ilV00e+LpVlNTaE+MYXCbep2EYGjEIz6VPw/Mveuw2hTy22Gmr1lCdqcxiyzfgYSFPCr/CGks87ysNHqiQE5m4xU3Qc4m24yg3xr8GOTffwR27DGf57KNnsgqQodCTmjtNXDGpMqdPh/lIi0/1GLGsKxxKL3cjX+9FSnSwbtJemYkTWnTZ1HKYq0QKZ25REZn8BhcO7pWIZm7HnsHR6kAFhni25PrrBTmZgLKlvBRgZZmw97L8wmGvE79FB3PNNpE5mPXOUrjOD8AKsZBidLil1V6KBpMEqSR3F3dPi5QsKxL/Bq0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 24 Feb 2026 10:41:53 +0530 Anshuman Khandual wrote: > 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. > > Since FEAT_D128 exclusively supports the permission indirection style for > page table entry permission management, given kernel compiled for FEAT_D128 > requires both FEAT_S1PIE and FEAT_D128. If these architecture features are > not present at boot, the kernel panics just like it does when there is a > granule size mismatch. > > TTBR0/1_EL1 and PAR_EL1 registers become 128 bit wide when D128 is enabled, > thus requiring MSRR/MRRS instructions for their updates. Because PA_BITS is > still capped at 52 bits, MRS/MSR instructions are currently sufficient for > the register accesses that basically operate on the lower 64 bits. Although > entire 128 bits for these registers get cleared during boot via MSRR. > > Add support for TLBIP instruction for TLB flush macros with level hint and > address range operations. Although existing TLBI based TLB flush would have > been sufficient given PA_BITS is still capped at 52, but then it would have > lacked both level hint and range support. > > This enables support for all granule size, VA_BITS and PA_BITS combination. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Ryan Roberts > Cc: Mark Rutland > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > arch/arm64/Kconfig | 39 ++++++- > arch/arm64/Makefile | 4 + > arch/arm64/include/asm/assembler.h | 4 +- > arch/arm64/include/asm/el2_setup.h | 9 ++ > arch/arm64/include/asm/pgtable-hwdef.h | 137 +++++++++++++++++++++++++ > arch/arm64/include/asm/pgtable-prot.h | 18 +++- > arch/arm64/include/asm/pgtable-types.h | 9 ++ > arch/arm64/include/asm/pgtable.h | 56 +++++++++- > arch/arm64/include/asm/smp.h | 1 + > arch/arm64/include/asm/tlbflush.h | 65 ++++++++++++ > arch/arm64/kernel/head.S | 12 +++ > arch/arm64/mm/proc.S | 25 ++++- > 12 files changed, 372 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 38dba5f7e4d2..aaf910295c39 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -309,6 +309,10 @@ config GCC_SUPPORTS_DYNAMIC_FTRACE_WITH_ARGS > def_bool CC_IS_GCC > depends on $(cc-option,-fpatchable-function-entry=2) > > +config CC_SUPPORTS_LSE128 > + def_bool CC_IS_GCC > + depends on $(cc-option, -march=armv8.1-a+lse128) > + > config 64BIT > def_bool y > > @@ -395,6 +399,16 @@ 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) > @@ -1504,7 +1518,7 @@ 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" > @@ -2195,6 +2209,29 @@ config ARM64_HAFT > > endmenu # "ARMv8.9 architectural features" > > +menu "ARMv9.3 architectural features" > + > +config AS_HAS_ARMV9_3 > + def_bool $(cc-option,-Wa$(comma)-march=armv9.3-a) > + > +config ARM64_D128 > + bool "Enable support for 128 bit page table (FEAT_D128)" > + depends on ARCH_SUPPORTS_INT128 > + depends on CC_SUPPORTS_LSE128 > + depends on AS_HAS_ARMV9_3 > + depends on EXPERT > + depends on !VIRTUALIZATION > + depends on !KASAN > + depends on !UNMAP_KERNEL_AT_EL0 > + default n > + help > + ARMv9.3 introduces FEAT_D128, which provides a 128 bit page > + table format, along with related instructions. > + > + If unsure, say Y. > + Should this say, If unsure, say N? > +endmenu # "ARMv9.3 architectural features" > + [...] > diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h > index 9c93ffbcc1e0..a221a1a9b87e 100644 > --- a/arch/arm64/include/asm/tlbflush.h > +++ b/arch/arm64/include/asm/tlbflush.h > @@ -49,6 +49,19 @@ > > #define __tlbi(op, ...) __TLBI_N(op, ##__VA_ARGS__, 1, 0) > > +#ifdef CONFIG_ARM64_D128 > +#define __tlbip(op, arg1, arg2) do { \ > + u128 value = 0; \ > + value |= (u128)arg2 << 64; \ > + value |= (u128)arg1; \ > + \ > + asm (ARM64_ASM_PREAMBLE \ > + ".arch_extension d128\n\t" \ > + "tlbip " #op ", %0, %H0\n" \ > + : : "r" (value)); \ > +} while (0) > +#endif > + > #define __tlbi_user(op, arg) do { \ > if (arm64_kernel_unmapped_at_el0()) \ > __tlbi(op, (arg) | USER_ASID_FLAG); \ > @@ -128,6 +141,46 @@ static inline unsigned long get_trans_granule(void) > __tlbi_level(op, (arg | USER_ASID_FLAG), level); \ > } while (0) > > +#ifdef CONFIG_ARM64_D128 > +/* > + * > + * TLBIP Encoding > + * > + * +------------+-----------------+-------+-------+------------------+ > + * | RES0 | BADDR | ASID | TTL | RES0 | > + * +------------------------------+-------+-------+------------------+ > + * |127 108|107 64|63 48|47 44|43 0| > + */ > + > +#define __tlbip_user(op, arg, addr) do { \ > + if (arm64_kernel_unmapped_at_el0()) \ > + __tlbip(op, (arg) | USER_ASID_FLAG, addr); \ > +} while (0) > +/* > + * FEAT_TTL being mandatory from armv8.4 and FEAT_D128 is available > + * only from armv9.4, we dont need the capability check for TTL. > + */ > +#define __TLBIP_ARGS(asid, level) \ > + ({ \ > + u64 arg = 0; \ > + \ > + arg |= FIELD_PREP(TLBI_ASID_MASK, (asid)); \ > + if ((level) >= 0 && (level) <= 3) { \ > + arg |= FIELD_PREP(TLBI_TG_MASK, get_trans_granule()); \ > + arg |= FIELD_PREP(TLBI_LVL_MASK, (level)); \ > + } \ > + arg; \ > + }) \ > + > +#define __tlb_asid_level(op, addr, asid, level, tlb_user) do { \ > + u64 arg1 = __TLBIP_ARGS(asid, level); \ > + u64 arg2 = (addr) >> 12; \ Does 12 over here represent PAGE_SHIFT? If so, would it break 16K and 64K PAGE_SIZE? > + \ > + __tlbip(op, arg1, arg2); \ > + if (tlb_user) \ > + __tlbip_user(op, arg1, arg2); \ > +} while (0) > +#else > #define __tlb_asid_level(op, addr, asid, level, tlb_user) do { \ > u64 arg1; \ > \