Re: [PATCH v4 06/16] riscv: Add Ziccamoa, Ziccif, Ziccrse, and Za64rs to cpufeature and hwprobe

[Jesse T]

On Thu, Jun 11, 2026 at 4:14 PM Guodong Xu <docular.xu@xxxxxxxxx> wrote:
>
> From: Andrew Jones <andrew.jones@xxxxxxxxxxxxxxxx>
>
> Add Ziccamoa, Ziccif, and Za64rs to riscv_isa_ext[] so they can be
> parsed from devicetree/ACPI ISA strings. Ziccrse is already present
> in cpufeature; this patch only adds its hwprobe exposure.
>
> Expose all four extensions via hwprobe through new bits in
> RISCV_HWPROBE_KEY_IMA_EXT_1 (RISCV_HWPROBE_EXT_ZICCAMOA, _ZICCIF,
> _ZICCRSE, _ZA64RS), so userspace can probe each of these
> RVA23U64-mandatory extensions individually.
>
> Rationale for the validation dependencies added for Ziccamoa and Za64rs:
>
> 1) Ziccamoa depends on Zaamo.  The RVA23 profile prose was updated
> post-ratification to spell out the Zaamo reference: commit
> 2b218613752d in riscv/riscv-profiles ("Improve description of
> Ziccamoa (#224)") reworded the rva23-profile.adoc (and other profiles
> that include Ziccamoa) text from "must support all atomics in A" to
> "must support all atomics in the Zaamo extension" [1].
>
> 2) Za64rs depends on Zalrsc. The unprivileged ISA manual src/zars.adoc,
> integrated in commit ebe06adc22cd ("Integrate profiles as Volume III
> (#2771)"), defines Za64rs as: "The Za64rs extension requires that the
> reservation sets used by the instructions in the Zalrsc extension be
> contiguous, naturally aligned, and at most 64 bytes in size" [2].
>
> Link: https://github.com/riscv/riscv-profiles/commit/2b218613752d63287286b5ae801b820cbd8cc10c [1]
> Link: https://github.com/riscv/riscv-isa-manual/blob/main/src/unpriv/zars.adoc [2]
> Signed-off-by: Andrew Jones <andrew.jones@xxxxxxxxxxxxxxxx>
> Signed-off-by: Guodong Xu <docular.xu@xxxxxxxxx>

Reviewed-by: Jesse Taube <jtaubepe@xxxxxxxxxx>

> ---
> v4: No change.
> v3: Indent the added hwprobe.rst entries to match the normalized style; no other change.
> v2:
> - Rebased to v7.1-rc2.
> - Reworded subject and expanded commit message.
> - Validation added for Ziccamoa depending on Zaamo and Za64rs depending
>   on Zalrsc.
> ---
>  Documentation/arch/riscv/hwprobe.rst  | 16 ++++++++++++++++
>  arch/riscv/include/asm/hwcap.h        |  3 +++
>  arch/riscv/include/uapi/asm/hwprobe.h |  4 ++++
>  arch/riscv/kernel/cpufeature.c        | 21 +++++++++++++++++++++
>  arch/riscv/kernel/sys_hwprobe.c       |  4 ++++
>  5 files changed, 48 insertions(+)
>
> diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
> index 49d9fb68632d0..893e1a1215d23 100644
> --- a/Documentation/arch/riscv/hwprobe.rst
> +++ b/Documentation/arch/riscv/hwprobe.rst
> @@ -405,3 +405,19 @@ The following keys are defined:
>    * :c:macro:`RISCV_HWPROBE_EXT_ZICCLSM`: The Zicclsm extension is supported,
>      as defined in the RISC-V Profiles specification starting from commit
>      b1d80660 ("Updated to ratified state.")
> +
> +  * :c:macro:`RISCV_HWPROBE_EXT_ZICCAMOA`: The Ziccamoa extension is supported,
> +    as defined in the RISC-V Profiles specification starting from commit
> +    b1d80660 ("Updated to ratified state.")
> +
> +  * :c:macro:`RISCV_HWPROBE_EXT_ZICCIF`: The Ziccif extension is supported,
> +    as defined in the RISC-V Profiles specification starting from commit
> +    b1d80660 ("Updated to ratified state.")
> +
> +  * :c:macro:`RISCV_HWPROBE_EXT_ZICCRSE`: The Ziccrse extension is supported,
> +    as defined in the RISC-V Profiles specification starting from commit
> +    b1d80660 ("Updated to ratified state.")
> +
> +  * :c:macro:`RISCV_HWPROBE_EXT_ZA64RS`: The Za64rs extension is supported,
> +    as defined in the RISC-V Profiles specification starting from commit
> +    b1d80660 ("Updated to ratified state.")
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index e8f4a7dd96a93..0acb7a01ecc0f 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -113,6 +113,9 @@
>  #define RISCV_ISA_EXT_ZICFILP          104
>  #define RISCV_ISA_EXT_ZICFISS          105
>  #define RISCV_ISA_EXT_ZICCLSM          106
> +#define RISCV_ISA_EXT_ZICCAMOA         107
> +#define RISCV_ISA_EXT_ZICCIF           108
> +#define RISCV_ISA_EXT_ZA64RS           109
>
>  #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 6819df159c51e..58d1e86e47ae7 100644
> --- a/arch/riscv/include/uapi/asm/hwprobe.h
> +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> @@ -117,6 +117,10 @@ struct riscv_hwprobe {
>  #define RISCV_HWPROBE_KEY_IMA_EXT_1            16
>  #define                RISCV_HWPROBE_EXT_ZICFISS       (1ULL << 0)
>  #define                RISCV_HWPROBE_EXT_ZICCLSM       (1ULL << 1)
> +#define                RISCV_HWPROBE_EXT_ZICCAMOA      (1ULL << 2)
> +#define                RISCV_HWPROBE_EXT_ZICCIF        (1ULL << 3)
> +#define                RISCV_HWPROBE_EXT_ZICCRSE       (1ULL << 4)
> +#define                RISCV_HWPROBE_EXT_ZA64RS        (1ULL << 5)
>
>  /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 1fb595581adcf..b9538e69fa1b3 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -90,6 +90,24 @@ static int riscv_ext_f_depends(const struct riscv_isa_ext_data *data,
>         return -EPROBE_DEFER;
>  }
>
> +static int riscv_ext_zaamo_depends(const struct riscv_isa_ext_data *data,
> +                                  const unsigned long *isa_bitmap)
> +{
> +       if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZAAMO))
> +               return 0;
> +
> +       return -EPROBE_DEFER;
> +}
> +
> +static int riscv_ext_zalrsc_depends(const struct riscv_isa_ext_data *data,
> +                                   const unsigned long *isa_bitmap)
> +{
> +       if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZALRSC))
> +               return 0;
> +
> +       return -EPROBE_DEFER;
> +}
> +
>  static int riscv_ext_zicbom_validate(const struct riscv_isa_ext_data *data,
>                                      const unsigned long *isa_bitmap)
>  {
> @@ -502,6 +520,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>         __RISCV_ISA_EXT_SUPERSET_VALIDATE(zicbom, RISCV_ISA_EXT_ZICBOM, riscv_xlinuxenvcfg_exts, riscv_ext_zicbom_validate),
>         __RISCV_ISA_EXT_DATA_VALIDATE(zicbop, RISCV_ISA_EXT_ZICBOP, riscv_ext_zicbop_validate),
>         __RISCV_ISA_EXT_SUPERSET_VALIDATE(zicboz, RISCV_ISA_EXT_ZICBOZ, riscv_xlinuxenvcfg_exts, riscv_ext_zicboz_validate),
> +       __RISCV_ISA_EXT_DATA_VALIDATE(ziccamoa, RISCV_ISA_EXT_ZICCAMOA, riscv_ext_zaamo_depends),
> +       __RISCV_ISA_EXT_DATA(ziccif, RISCV_ISA_EXT_ZICCIF),
>         __RISCV_ISA_EXT_DATA(zicclsm, RISCV_ISA_EXT_ZICCLSM),
>         __RISCV_ISA_EXT_DATA(ziccrse, RISCV_ISA_EXT_ZICCRSE),
>         __RISCV_ISA_EXT_SUPERSET_VALIDATE(zicfilp, RISCV_ISA_EXT_ZICFILP, riscv_xlinuxenvcfg_exts,
> @@ -516,6 +536,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>         __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
>         __RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
>         __RISCV_ISA_EXT_DATA(zimop, RISCV_ISA_EXT_ZIMOP),
> +       __RISCV_ISA_EXT_DATA_VALIDATE(za64rs, RISCV_ISA_EXT_ZA64RS, riscv_ext_zalrsc_depends),
>         __RISCV_ISA_EXT_DATA(zaamo, RISCV_ISA_EXT_ZAAMO),
>         __RISCV_ISA_EXT_DATA(zabha, RISCV_ISA_EXT_ZABHA),
>         __RISCV_ISA_EXT_DATA(zacas, RISCV_ISA_EXT_ZACAS),
> diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
> index 9cf62266f1890..b15ac9adf7920 100644
> --- a/arch/riscv/kernel/sys_hwprobe.c
> +++ b/arch/riscv/kernel/sys_hwprobe.c
> @@ -206,6 +206,10 @@ static void hwprobe_isa_ext1(struct riscv_hwprobe *pair,
>                  */
>                 EXT_KEY(isainfo->isa, ZICFISS, pair->value, missing);
>                 EXT_KEY(isainfo->isa, ZICCLSM, pair->value, missing);
> +               EXT_KEY(isainfo->isa, ZICCAMOA, pair->value, missing);
> +               EXT_KEY(isainfo->isa, ZICCIF, pair->value, missing);
> +               EXT_KEY(isainfo->isa, ZICCRSE, pair->value, missing);
> +               EXT_KEY(isainfo->isa, ZA64RS, pair->value, missing);
>         }
>
>         /* Now turn off reporting features if any CPU is missing it. */
>
> --
> 2.43.0
>
>
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