[PATCH v3 0/8] riscv: Add Zalasr ISA extension support

Xu Lu
2025-09-19T07:37:29Z

This patch adds support for the Zalasr ISA extension, which supplies the
real load acquire/store release instructions.

The specification can be found here:
https://github.com/riscv/riscv-zalasr/blob/main/chapter2.adoc

This patch seires has been tested with ltp on Qemu with Brensan's zalasr
support patch[1].

Some false positive spacing error happens during patch checking. Thus I
CCed maintainers of checkpatch.pl as well.

[1] https://lore.kernel.org/all/CAGPSXwJEdtqW=nx71oufZp64nK6tK=0rytVEcz4F-gfvCOXk2w@mail.gmail.com/

v3:
- Apply acquire/release semantics to arch_xchg/arch_cmpxchg operations
so as to ensure FENCE.TSO ordering between operations which precede the
UNLOCK+LOCK sequence and operations which follow the sequence. Thanks
to Andrea.
- Support hwprobe of Zalasr.
- Allow Zalasr extensions for Guest/VM.

v2:
- Adjust the order of Zalasr and Zalrsc in dt-bindings. Thanks to
Conor.

Xu Lu (8):
riscv: add ISA extension parsing for Zalasr
dt-bindings: riscv: Add Zalasr ISA extension description
riscv: hwprobe: Export Zalasr extension
riscv: Introduce Zalasr instructions
riscv: Use Zalasr for smp_load_acquire/smp_store_release
riscv: Apply acquire/release semantics to arch_xchg/arch_cmpxchg
operations
RISC-V: KVM: Allow Zalasr extensions for Guest/VM
KVM: riscv: selftests: Add Zalasr extensions to get-reg-list test

Documentation/arch/riscv/hwprobe.rst | 5 +-
.../devicetree/bindings/riscv/extensions.yaml | 5 +
arch/riscv/include/asm/atomic.h | 6 -
arch/riscv/include/asm/barrier.h | 91 ++++++++++--
arch/riscv/include/asm/cmpxchg.h | 136 ++++++++----------
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/include/asm/insn-def.h | 79 ++++++++++
arch/riscv/include/uapi/asm/hwprobe.h | 1 +
arch/riscv/include/uapi/asm/kvm.h | 1 +
arch/riscv/kernel/cpufeature.c | 1 +
arch/riscv/kernel/sys_hwprobe.c | 1 +
arch/riscv/kvm/vcpu_onereg.c | 2 +
.../selftests/kvm/riscv/get-reg-list.c | 4 +
13 files changed, 242 insertions(+), 91 deletions(-)

--
2.20.1