Gentle ping in case of forgotten.
On Wed, Jan 21, 2026 at 07:06:15PM +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-rc6
>
> Patch History
> ==============
> from v11 to v12:
> - rebase to v6.19-rc6
> - add CONFIG_ARM64_LSUI
> - enable LSUI when !CPU_BIG_ENDIAN and PAN presents.
> - drop the swp emulation with LSUI insns instead, disable it
> when LSUI presents.
> - some of small fixes (useless prefix and suffix and etc).
> - https://lore.kernel.org/all/[email protected]/
>
> from v10 to v11:
> - rebase to v6.19-rc1
> - use cast instruction to emulate deprecated swpb instruction
> - https://lore.kernel.org/all/[email protected]/
>
> 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/[email protected]/
>
> from v8 to v9:
> - refotoring __lsui_cmpxchg64()
> - rebase to v6.17-rc7
> - https://lore.kernel.org/all/[email protected]/
>
> 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/[email protected]/
>
> 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/[email protected]/
>
> from v5 to v6:
> - rebase to v6.17-rc1
> - https://lore.kernel.org/all/[email protected]/
>
> 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/[email protected]/
>
> from v3 to v4:
> - rebase to v6.16-rc7
> - modify some patch's title.
> - https://lore.kernel.org/all/[email protected]/
>
> from v2 to v3:
> - expose FEAT_LSUI to guest
> - add help section for LSUI Kconfig
> - https://lore.kernel.org/all/[email protected]/
>
> from v1 to v2:
> - remove empty v9.6 menu entry
> - locate HAS_LSUI in cpucaps in order
> - https://lore.kernel.org/all/[email protected]/
>
>
> Yeoreum Yun (7):
> arm64: Kconfig: add support for LSUI
> arm64: cpufeature: add FEAT_LSUI
> KVM: arm64: expose FEAT_LSUI to guest
> KVM: arm64: kselftest: set_id_regs: add test for FEAT_LSUI
> arm64: futex: refactor futex atomic operation
> arm64: futex: support futex with FEAT_LSUI
> arm64: armv8_deprecated: disable swp emulation when FEAT_LSUI present
>
> arch/arm64/Kconfig | 20 ++
> arch/arm64/include/asm/futex.h | 322 +++++++++++++++---
> arch/arm64/kernel/armv8_deprecated.c | 16 +
> arch/arm64/kernel/cpufeature.c | 27 ++
> arch/arm64/kvm/sys_regs.c | 3 +-
> arch/arm64/tools/cpucaps | 1 +
> .../testing/selftests/kvm/arm64/set_id_regs.c | 1 +
> 7 files changed, 339 insertions(+), 51 deletions(-)
>
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>
--
Sincerely,
Yeoreum Yun
