Re: [PATCH RESEND v7 0/6] support FEAT_LSUI and apply it on futex atomic ops

[Yeoreum Yun <yeoreum.yun@arm.com>]

Gentle ping in case of forgotten.

On Sat, Aug 16, 2025 at 04:19:23PM +0100, 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
> where can replace from ldxr/stlxr pair implmentation with clearing
> PSTATE.PAN bit to correspondant load/store unprevileged atomic operation
> without clearing PSTATE.PAN bit.
>
> (Sorry, I've sent wrongly for patch version 7 and resend it.
>  Again, sorry for mail-boom).
>
> Patch Sequences
> ================
>
> Patch #1 adds cpufeature for FEAT_LSUI
>
> Patch #2 expose FEAT_LSUI to guest
>
> Patch #3 adds Kconfig for FEAT_LSUI
>
> Patch #4 refactor former futex atomic-op implmentation with ll/sc &
>          clearing PSTATE.PAN
>
> Patch #5 applies small optimisation for __llc_futex_atomic_set().
>
> Patch #6 support futext atomic-op with FEAT_LSUI
>
> Patch History
> ==============
> 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 (6):
>   arm64: cpufeature: add FEAT_LSUI
>   KVM: arm64: expose FEAT_LSUI to guest
>   arm64: Kconfig: add LSUI Kconfig
>   arm64: futex: refactor futex atomic operation
>   arm64: futex: small optimisation for __llsc_futex_atomic_set()
>   arm64: futex: support futex with FEAT_LSUI
>
>  arch/arm64/Kconfig             |   5 +
>  arch/arm64/include/asm/futex.h | 291 +++++++++++++++++++++++++++------
>  arch/arm64/kernel/cpufeature.c |  10 ++
>  arch/arm64/kvm/sys_regs.c      |   5 +-
>  arch/arm64/tools/cpucaps       |   1 +
>  5 files changed, 261 insertions(+), 51 deletions(-)
>
>
> base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>

--
Sincerely,
Yeoreum Yun