From: Anshuman Khandual <anshuman.khandual@arm•com>
To: Lorenzo Stoakes <ljs@kernel•org>
Cc: linux-arm-kernel@lists•infradead.org,
Catalin Marinas <catalin.marinas@arm•com>,
Will Deacon <will@kernel•org>,
Ryan Roberts <ryan.roberts@arm•com>,
Mark Rutland <mark.rutland@arm•com>,
Andrew Morton <akpm@linux-foundation•org>,
David Hildenbrand <david@kernel•org>,
Mike Rapoport <rppt@kernel•org>,
Linu Cherian <linu.cherian@arm•com>,
Usama Arif <usama.arif@linux•dev>,
linux-kernel@vger•kernel.org, linux-mm@kvack•org
Subject: Re: [RFC V2 00/14] arm64/mm: Enable 128 bit page table entries
Date: Mon, 18 May 2026 09:50:55 +0530 [thread overview]
Message-ID: <50e91f4f-f44f-4457-aa44-abd877e5e241@arm.com> (raw)
In-Reply-To: <agRF7FXwCvp4Ec3h@lucifer>
On 13/05/26 3:09 PM, Lorenzo Stoakes wrote:
> -cc my previous kernel address
>
> Hi Anshuman,
>
> Sorry to be a pain, but I'm using ljs@kernel•org now for my kernel mail, so
> I am at risk of missing stuff sent to my @oracle.com address (I changed
> things around to make managing the... rather large quantities of mail I get
> a bit easier :)
>
> Hence I missed this previously, can you send future revisions to
> ljs@kernel•org? Thanks!
Sure, will do.
>
> Cheers, Lorenzo
>
> On Wed, May 13, 2026 at 10:15:33AM +0530, Anshuman Khandual wrote:
>> FEAT_D128 is a new arm architecture feature adding support for VMSAv9-128
>> translation system. FEAT_D128 is an optional feature from ARMV9.3 onwards.
>> So with this feature arm64 platforms could have two different translation
>> systems, VMSAv8-64 and VMSAv9-128 could selectively be enabled.
>>
>> FEAT_D128 adds 128 bit page table entries, thus supporting larger physical
>> and virtual address range while also expanding available room for more MMU
>> management feature bits both for HW and SW.
>>
>> This series has been split into two parts. Generic MM changes followed by
>> arm64 platform changes, finally enabling D128 with a new config ARM64_D128.
>>
>> READ_ONCE() on page table entries get routed via level specific pxdp_get()
>> helpers which platforms could then override when required. These accessors
>> on arm64 platform help in ensuring page table accesses are performed in an
>> atomic manner while reading 128 bit page table entries.
>>
>> All ARM64_VA_BITS and ARM64_PA_BITS combinations for all page sizes are now
>> supported both on D64 and D128 translation regimes. Although new 56 bits VA
>> space is not yet supported. Similarly FEAT_D128 skip level is not supported
>> currently.
>>
>> Basic page table geometry has also been changed with D128 as there are fewer
>> entries per level. Please refer to the following table for leaf entry sizes.
>>
>> D64 D128
>> ------------------------------------------------
>> | PAGE_SIZE | PMD | PUD | PMD | PUD |
>> -----------------------------|-----------------|
>> | 4K | 2M | 1G | 1M | 256M |
>> | 16K | 32M | 64G | 16M | 16G |
>> | 64K | 512M | 4T | 256M | 1T |
>> ------------------------------------------------
>>
>> D64 D128
>> --------------------------------------------------------------------
>> | PAGE_SIZE | CONT_PTE | CONT_PMD | CONT_PTE | CONT_PMD |
>> --------------------------|------------|-------------|--------------
>> | 4K | 64K | 32M | 64K | 16M |
>> | 16K | 2M | 1G | 1M | 256M |
>> | 64K | 2M | 16G | 1M | 16G |
>> --------------------------------------------------------------------
>>
>> From arm64 kernel features perspective KVM, KASAN and UNMAP_KERNEL_AT_EL0
>> are currently not supported as well.
>>
>> This series applies on v7.1-rc3 and there are no apparent problems while
>> running MM kselftests with and without CONFIG_ARM64_D128. Besides this has
>> been built tested on other platform such as x86, powerpc, riscv, arm and
>> s390 etc.
>>
>> Changes in RFC V2:
>>
>> - Dropped some patches that were merged upstream and rebased on v7.1-rc3
>> - Moved pxdval_t definition inside generic page table header per Mike
>> - Restored print format in __print_bad_page_map_pgtable() per Usama
>> - Renamed __PRIpte as __PRIpxx per David
>> - Dropped _once from pgprot_[read|write]() callbacks per Mike
>> - Moved back all helpers back from arch/arm64/mm/mmu.c into the header
>> - Renamed all ptdesc_ instances as pxxval_ instead
>> - Moved arm64 pgtable header READ_ONCE() replacements later in the series
>> - Updated commit message for the 5-level fixmap change per David
>> - Updated ARM64_CONT_[PTE|PMD]_SHIFT both for 16K and 64K base pages
>> - Added abstraction for tlbi_op
>> - Adopted TLBIP implementation to recent TLB flush changes
>> - Updated all commit messages as required and suggested
>>
>> Changes in RFC V1:
>>
>> https://lore.kernel.org/linux-arm-kernel/20260224051153.3150613-2-anshuman.khandual@arm.com/
>>
>> 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: Lorenzo Stoakes <lorenzo.stoakes@oracle•com>
>> Cc: Andrew Morton <akpm@linux-foundation•org>
>> Cc: David Hildenbrand <david@kernel•org>
>> Cc: Mike Rapoport <rppt@kernel•org>
>> Cc: Linu Cherian <linu.cherian@arm•com>
>> Cc: Usama Arif <usama.arif@linux•dev>
>> Cc: linux-arm-kernel@lists•infradead.org
>> Cc: linux-kernel@vger•kernel.org
>> Cc: linux-mm@kvack•org
>>
>> Anshuman Khandual (13):
>> mm: Abstract printing of pxd_val()
>> mm: Add read-write accessors for vm_page_prot
>> arm64/mm: Convert READ_ONCE() as pmdp_get() while accessing PMD
>> arm64/mm: Convert READ_ONCE() as pudp_get() while accessing PUD
>> arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D
>> arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD
>> arm64/mm: Route all pgtable reads via pxxval_get()
>> arm64/mm: Route all pgtable writes via pxxval_set()
>> arm64/mm: Route all pgtable atomics to central helpers
>> arm64/mm: Abstract printing of pxd_val()
>> arm64/mm: Override read-write accessors for vm_page_prot
>> arm64/mm: Enable fixmap with 5 level page table
>> arm64/mm: Add initial support for FEAT_D128 page tables
>>
>> Linu Cherian (1):
>> arm64/mm: Add an abstraction level for tlbi_op
>>
>> arch/arm64/Kconfig | 51 +++++++-
>> 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 | 12 ++
>> arch/arm64/include/asm/pgtable.h | 169 ++++++++++++++++++++-----
>> arch/arm64/include/asm/smp.h | 1 +
>> arch/arm64/include/asm/tlbflush.h | 138 ++++++++++++++------
>> arch/arm64/kernel/head.S | 12 ++
>> arch/arm64/mm/fault.c | 20 +--
>> arch/arm64/mm/fixmap.c | 24 +++-
>> arch/arm64/mm/hugetlbpage.c | 10 +-
>> arch/arm64/mm/kasan_init.c | 14 +-
>> arch/arm64/mm/mmu.c | 65 +++++-----
>> arch/arm64/mm/pageattr.c | 8 +-
>> arch/arm64/mm/proc.S | 25 +++-
>> arch/arm64/mm/trans_pgd.c | 14 +-
>> include/linux/pgtable.h | 25 ++++
>> mm/huge_memory.c | 4 +-
>> mm/memory.c | 25 ++--
>> mm/migrate.c | 2 +-
>> mm/mmap.c | 2 +-
>> 24 files changed, 624 insertions(+), 169 deletions(-)
>>
>> --
>> 2.43.0
>>
prev parent reply other threads:[~2026-05-18 4:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 4:45 [RFC V2 00/14] arm64/mm: Enable 128 bit page table entries Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 01/14] mm: Abstract printing of pxd_val() Anshuman Khandual
2026-05-17 18:57 ` Mike Rapoport
2026-05-19 14:28 ` Dave Hansen
2026-05-20 10:41 ` David Hildenbrand (Arm)
2026-05-21 3:43 ` Anshuman Khandual
2026-05-21 9:42 ` David Laight
2026-06-01 6:26 ` Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 02/14] mm: Add read-write accessors for vm_page_prot Anshuman Khandual
2026-05-17 18:59 ` Mike Rapoport
2026-05-13 4:45 ` [RFC V2 03/14] arm64/mm: Convert READ_ONCE() as pmdp_get() while accessing PMD Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 04/14] arm64/mm: Convert READ_ONCE() as pudp_get() while accessing PUD Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 05/14] arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 06/14] arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 07/14] arm64/mm: Route all pgtable reads via pxxval_get() Anshuman Khandual
2026-05-27 14:11 ` Ryan Roberts
2026-06-01 5:01 ` Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 08/14] arm64/mm: Route all pgtable writes via pxxval_set() Anshuman Khandual
2026-05-27 14:12 ` Ryan Roberts
2026-05-13 4:45 ` [RFC V2 09/14] arm64/mm: Route all pgtable atomics to central helpers Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 10/14] arm64/mm: Abstract printing of pxd_val() Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 11/14] arm64/mm: Override read-write accessors for vm_page_prot Anshuman Khandual
2026-05-13 4:45 ` [RFC V2 13/14] arm64/mm: Add an abstraction level for tlbi_op Anshuman Khandual
2026-05-27 14:50 ` Ryan Roberts
2026-05-29 4:02 ` Linu Cherian
2026-06-01 5:36 ` Anshuman Khandual
2026-06-01 11:06 ` Dev Jain
2026-05-13 4:45 ` [RFC V2 14/14] arm64/mm: Add initial support for FEAT_D128 page tables Anshuman Khandual
2026-05-27 14:54 ` Ryan Roberts
2026-06-01 10:52 ` Linu Cherian
2026-05-13 9:39 ` [RFC V2 00/14] arm64/mm: Enable 128 bit page table entries Lorenzo Stoakes
2026-05-18 4:20 ` Anshuman Khandual [this message]
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