[PATCH v12 0/7] support FEAT_LSUI

[Yeoreum Yun]

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/20251214112248.901769-1-yeoreum....@arm.com/

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....@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....@arm.com/

from v8 to v9:
  - refotoring __lsui_cmpxchg64()
  - rebase to v6.17-rc7
  - https://lore.kernel.org/all/20250917110838.917281-1-yeoreum....@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....@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....@arm.com/

from v5 to v6:
  - rebase to v6.17-rc1
  - https://lore.kernel.org/all/20250722121956.1509403-1-yeoreum....@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....@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....@arm.com/

from v2 to v3:
  - expose FEAT_LSUI to guest
  - add help section for LSUI Kconfig
  - https://lore.kernel.org/all/20250611151154.46362-1-yeoreum....@arm.com/

from v1 to v2:
  - remove empty v9.6 menu entry
  - locate HAS_LSUI in cpucaps in order
  - https://lore.kernel.org/all/20250611104916.10636-1-yeoreum....@arm.com/


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(-)

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