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b=ldhuKbdqCzllph7J2oBe1tFll52xEIvi/X5XGIsQ9jlPH3V0+5FbslEKFvpvKUiey HSKP1mujb09J9IRarHFIY+IvP8fHk1kSV3cbnMYwTayb3UO0mgP9sfcdRQntIkGUTu 8hAczgPHMmt8pRtF4EuoQhgN7nQeAdY1hvBLLOt7mrjk4pQLM6V3UWowNDtbhyBRjw YCW00YAQABZgtqpqyraWAbwmBydtOYzf1m+oxQGD9sgkosK/znBBNIdMFnhh1kZInm UG/vKw205xcei0CUxLtGjz5m1s4IYeEFwqoa9JVp50Qxbmoc9fsBf4bBFGgLVI7PCo //3toDnC0mkUw== Date: Wed, 13 May 2026 10:39:27 +0100 From: Lorenzo Stoakes To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Andrew Morton , David Hildenbrand , Mike Rapoport , Linu Cherian , Usama Arif , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC V2 00/14] arm64/mm: Enable 128 bit page table entries Message-ID: References: <20260513044547.4128549-1-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260513044547.4128549-1-anshuman.khandual@arm.com> X-Stat-Signature: xk9niyky9c5z7rjceoss8qaxdectebpi X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0D35720005 X-Rspam-User: X-HE-Tag: 1778665170-250396 X-HE-Meta: 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 m5s8RfIu hswgg8fRxwvOg02AmV0e4OLb1RLByD5tgXy2x3b60IWb20advY0lwGopky80qG9rFV/s8S1R4PNlVBzz0/moK2VXSbEYk88AadylZ5FTN1Ep0/50OojPSKSrv6NZeEs6wJwW3aPaeJZcs8b5BzY714OZF+H/4e0QPXO3bgOD8KX5upBnCncFb0GBxnms6syiEuMT5RFjtFBEMmqnOHN+J01WS1a4NMRO8Cx6K8uAbjAycJOS5rFeN7AnlPL9vgVszLjPOs2CX75N4JUOZi6H7jDd1AuNMaQc0Zdy5Iv0uIjN0iIdpPzrNRLPkT3+H4ELW3t6a61PSdHmvw07QZnBbmfkw9Dp8MA9fnyyc68K0onEkhjWxXPiTs1TVaeS3508WGUaAnxUynzTwxmkp79PC43kH/2koaZBGU7+u8jWFJBOjNyXZfoMcaRXMPs5rm2s1qf6KKjrMUMMqKWblXx/kIIQBAiBcwluVCSmk6wqBUJOO3Zetm3X4dzlSwD/8L3sI1OXFO8mtG1SqU0McABpkviZOjmGp4weXDYXT Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: -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! 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 > Cc: Will Deacon > Cc: Ryan Roberts > Cc: Mark Rutland > Cc: Lorenzo Stoakes > Cc: Andrew Morton > Cc: David Hildenbrand > Cc: Mike Rapoport > Cc: Linu Cherian > Cc: Usama Arif > 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 >