Re: [PATCH v11 RESEND 0/9] support FEAT_LSUI

Yeoreum Yun
2025-12-31T10:09:11Z

Gentle ping in case of forgotten.

On Sun, Dec 14, 2025 at 11:22:39AM +0000, Yeoreum Yun wrote:
> Since Armv9.6, FEAT_LSUI supplies the load/store instructions for
> previleged level to access to access user memory without clearing
> PSTATE.PAN bit.
>
> This patchset support FEAT_LSUI and applies in futex atomic operation
> and user_swpX emulation where can replace from ldxr/st{l}xr
> pair implmentation with clearing PSTATE.PAN bit to correspondant
> load/store unprevileged atomic operation without clearing PSTATE.PAN bit.
>
> This patch based on v6.19-rc1
>
>
> Patch Sequences
> ================
>
> Patch #1 adds cpufeature for FEAT_LSUI
>
> Patch #2-#3 expose FEAT_LSUI to guest
>
> Patch #4 adds Kconfig for FEAT_LSUI
>
> Patch #5-#6 support futex atomic-op with FEAT_LSUI
>
> Patch #7-#9 support user_swpX emulation with FEAT_LSUI
>
>
> Patch History
> ==============
> from v10 to v11:
> - rebase to v6.19-rc1
> - use cast instruction to emulate deprecated swpb instruction
> - https://lore.kernel.org/all/20251103163224.818353-1-yeoreum.yun@arm.com/
>
> from v9 to v10:
> - apply FEAT_LSUI to user_swpX emulation.
> - add test coverage for LSUI bit in ID_AA64ISAR3_EL1
> - rebase to v6.18-rc4
> - https://lore.kernel.org/all/20250922102244.2068414-1-yeoreum.yun@arm.com/
>
> from v8 to v9:
> - refotoring __lsui_cmpxchg64()
> - rebase to v6.17-rc7
> - https://lore.kernel.org/all/20250917110838.917281-1-yeoreum.yun@arm.com/
>
> from v7 to v8:
> - implements futex_atomic_eor() and futex_atomic_cmpxchg() with casalt
> with C helper.
> - Drop the small optimisation on ll/sc futex_atomic_set operation.
> - modify some commit message.
> - https://lore.kernel.org/all/20250816151929.197589-1-yeoreum.yun@arm.com/
>
> from v6 to v7:
> - wrap FEAT_LSUI with CONFIG_AS_HAS_LSUI in cpufeature
> - remove unnecessary addition of indentation.
> - remove unnecessary mte_tco_enable()/disable() on LSUI operation.
> - https://lore.kernel.org/all/20250811163635.1562145-1-yeoreum.yun@arm.com/
>
> from v5 to v6:
> - rebase to v6.17-rc1
> - https://lore.kernel.org/all/20250722121956.1509403-1-yeoreum.yun@arm.com/
>
> from v4 to v5:
> - remove futex_ll_sc.h futext_lsui and lsui.h and move them to futex.h
> - reorganize the patches.
> - https://lore.kernel.org/all/20250721083618.2743569-1-yeoreum.yun@arm.com/
>
> from v3 to v4:
> - rebase to v6.16-rc7
> - modify some patch's title.
> - https://lore.kernel.org/all/20250617183635.1266015-1-yeoreum.yun@arm.com/
>
> from v2 to v3:
> - expose FEAT_LUSI to guest
> - add help section for LUSI Kconfig
> - https://lore.kernel.org/all/20250611151154.46362-1-yeoreum.yun@arm.com/
>
> from v1 to v2:
> - remove empty v9.6 menu entry
> - locate HAS_LUSI in cpucaps in order
> - https://lore.kernel.org/all/20250611104916.10636-1-yeoreum.yun@arm.com/
>
>
> Yeoreum Yun (9):
> arm64: cpufeature: add FEAT_LSUI
> KVM: arm64: expose FEAT_LSUI to guest
> KVM: arm64: kselftest: set_id_regs: add test for FEAT_LSUI
> arm64: Kconfig: Detect toolchain support for LSUI
> arm64: futex: refactor futex atomic operation
> arm64: futex: support futex with FEAT_LSUI
> arm64: separate common LSUI definitions into lsui.h
> arm64: armv8_deprecated: convert user_swpX to inline function
> arm64: armv8_deprecated: apply FEAT_LSUI for swpX emulation.
>
> arch/arm64/Kconfig | 5 +
> arch/arm64/include/asm/futex.h | 291 +++++++++++++++---
> arch/arm64/include/asm/lsui.h | 25 ++
> arch/arm64/kernel/armv8_deprecated.c | 111 +++++--
> arch/arm64/kernel/cpufeature.c | 10 +
> arch/arm64/kvm/sys_regs.c | 3 +-
> arch/arm64/tools/cpucaps | 1 +
> .../testing/selftests/kvm/arm64/set_id_regs.c | 1 +
> 8 files changed, 381 insertions(+), 66 deletions(-)
> create mode 100644 arch/arm64/include/asm/lsui.h
>
>
> base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>

--
Sincerely,
Yeoreum Yun