Re: [PATCH 1/2] RISC-V: Add Zicclsm to cpufeature and hwprobe

Charlie Jenkins
2024-08-09T18:50:01Z

On Fri, Aug 09, 2024 at 12:22:39PM -0400, Jesse Taube wrote:
> > Zicclsm Misaligned loads and stores to main memory regions with both
> > the cacheability and coherence PMAs must be supported.
> > Note:
> > This introduces a new extension name for this feature.
> > This requires misaligned support for all regular load and store
> > instructions (including scalar and vector) but not AMOs or other
> > specialized forms of memory access. Even though mandated, misaligned
> > loads and stores might execute extremely slowly. Standard software
> > distributions should assume their existence only for correctness,
> > not for performance.

You left in the > characters.

Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>

>
> Signed-off-by: Jesse Taube <jesse@rivosinc.com>
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
> ---
> V1 -> V2:
> - Add documentation for Zicclsm
> - Move Zicclsm to correct location
> V2 -> V3:
> - No changes
> V3 -> V4:
> - Add definitions to hwprobe.rst
> V4 -> V5:
> - No changes
> V5 -> V6:
> - No changes
> V6 -> V7:
> - No changes
> V7 -> V8:
> - Rebase onto 2d1f51d8a4b0 (palmer/for-next)
> - Change commit description
> ---
> Documentation/arch/riscv/hwprobe.rst | 5 +++++
> arch/riscv/include/asm/hwcap.h | 1 +
> arch/riscv/include/uapi/asm/hwprobe.h | 1 +
> arch/riscv/kernel/cpufeature.c | 1 +
> arch/riscv/kernel/sys_hwprobe.c | 1 +
> 5 files changed, 9 insertions(+)
>
> diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
> index 3db60a0911df..22c118df520b 100644
> --- a/Documentation/arch/riscv/hwprobe.rst
> +++ b/Documentation/arch/riscv/hwprobe.rst
> @@ -239,6 +239,11 @@ The following keys are defined:
> ratified in commit 98918c844281 ("Merge pull request #1217 from
> riscv/zawrs") of riscv-isa-manual.
>
> + * :c:macro:`RISCV_HWPROBE_EXT_ZICCLSM`: The Zicclsm extension is supported as
> + defined in the RISC-V RVA Profiles Specification. Misaligned support for
> + all regular load and store instructions (including scalar and vector) but
> + not AMOs or other specialized forms of memory access.
> +
> * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
> information about the selected set of processors.
>
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 5a0bd27fd11a..c93d957458f0 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -92,6 +92,7 @@
> #define RISCV_ISA_EXT_ZCF 83
> #define RISCV_ISA_EXT_ZCMOP 84
> #define RISCV_ISA_EXT_ZAWRS 85
> +#define RISCV_ISA_EXT_ZICCLSM 86
>
> #define RISCV_ISA_EXT_XLINUXENVCFG 127
>
> diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
> index b706c8e47b02..a9370968fc9f 100644
> --- a/arch/riscv/include/uapi/asm/hwprobe.h
> +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> @@ -72,6 +72,7 @@ struct riscv_hwprobe {
> #define RISCV_HWPROBE_EXT_ZCF (1ULL << 46)
> #define RISCV_HWPROBE_EXT_ZCMOP (1ULL << 47)
> #define RISCV_HWPROBE_EXT_ZAWRS (1ULL << 48)
> +#define RISCV_HWPROBE_EXT_ZICCLSM (1ULL << 49)
> #define RISCV_HWPROBE_KEY_CPUPERF_0 5
> #define RISCV_HWPROBE_MISALIGNED_UNKNOWN (0 << 0)
> #define RISCV_HWPROBE_MISALIGNED_EMULATED (1 << 0)
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 8f20607adb40..2f54d811a9b8 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -314,6 +314,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
> riscv_ext_zicbom_validate),
> __RISCV_ISA_EXT_SUPERSET_VALIDATE(zicboz, RISCV_ISA_EXT_ZICBOZ, riscv_xlinuxenvcfg_exts,
> riscv_ext_zicboz_validate),
> + __RISCV_ISA_EXT_DATA(zicclsm, RISCV_ISA_EXT_ZICCLSM),
> __RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
> __RISCV_ISA_EXT_DATA(zicond, RISCV_ISA_EXT_ZICOND),
> __RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
> diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
> index 8d1b5c35d2a7..01eea29a56cd 100644
> --- a/arch/riscv/kernel/sys_hwprobe.c
> +++ b/arch/riscv/kernel/sys_hwprobe.c
> @@ -107,6 +107,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
> EXT_KEY(ZCB);
> EXT_KEY(ZCMOP);
> EXT_KEY(ZICBOZ);
> + EXT_KEY(ZICCLSM);
> EXT_KEY(ZICOND);
> EXT_KEY(ZIHINTNTL);
> EXT_KEY(ZIHINTPAUSE);
> --
> 2.45.2
>