Re: [PATCH 2/3] RISC-V: hwprobe: Expose Zbc and the scalar crypto extensions

From: Stefan O'Rear
Date: Tue Jun 27 2023 - 20:34:56 EST

On Tue, Jun 27, 2023, at 10:37 AM, Samuel Ortiz wrote:
> Zbc was missing from a previous Bit-Manipulation extension hwprobe
> patch.
>
> Add all scalar crypto extensions bits, and define a macro for setting
> the hwprobe key/pair in a more readable way.
>
> Signed-off-by: Samuel Ortiz <sameo@xxxxxxxxxxxx>
> ---
> Documentation/riscv/hwprobe.rst | 33 ++++++++++++++++++++++++
> arch/riscv/include/uapi/asm/hwprobe.h | 11 ++++++++
> arch/riscv/kernel/sys_riscv.c | 36 ++++++++++++++++-----------
> 3 files changed, 66 insertions(+), 14 deletions(-)
>
> diff --git a/Documentation/riscv/hwprobe.rst b/Documentation/riscv/hwprobe.rst
> index 19165ebd82ba..3177550106e0 100644
> --- a/Documentation/riscv/hwprobe.rst
> +++ b/Documentation/riscv/hwprobe.rst
> @@ -72,11 +72,44 @@ The following keys are defined:
> extensions.
>
> * :c:macro:`RISCV_HWPROBE_EXT_ZBB`: The Zbb extension is supported,
> as defined
> + in version 1.0 of the Bit-Manipulation ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZBC`: The Zbc extension is supported,
> as defined
> in version 1.0 of the Bit-Manipulation ISA extensions.
>
> * :c:macro:`RISCV_HWPROBE_EXT_ZBS`: The Zbs extension is supported,
> as defined
> in version 1.0 of the Bit-Manipulation ISA extensions.
>
> + * :c:macro:`RISCV_HWPROBE_EXT_ZBKB`: The Zbkb extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZBKC`: The Zbkc extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZBKX`: The Zbkx extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKND`: The Zknd extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKNE`: The Zkne extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKNH`: The Zknh extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKR`: The Zkr extension is supported,
> as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKSED`: The Zksed extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKSH`: The Zksh extension is
> supported, as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> + * :c:macro:`RISCV_HWPROBE_EXT_ZKT`: The Zkt extension is supported,
> as defined
> + in version 1.0 of the Scalar Cryptography ISA extensions.
> +
> * :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/uapi/asm/hwprobe.h
> b/arch/riscv/include/uapi/asm/hwprobe.h
> index 006bfb48343d..8357052061b3 100644
> --- a/arch/riscv/include/uapi/asm/hwprobe.h
> +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> @@ -29,6 +29,17 @@ struct riscv_hwprobe {
> #define RISCV_HWPROBE_EXT_ZBA (1 << 3)
> #define RISCV_HWPROBE_EXT_ZBB (1 << 4)
> #define RISCV_HWPROBE_EXT_ZBS (1 << 5)
> +#define RISCV_HWPROBE_EXT_ZBC (1 << 6)
> +#define RISCV_HWPROBE_EXT_ZBKB (1 << 7)
> +#define RISCV_HWPROBE_EXT_ZBKC (1 << 8)
> +#define RISCV_HWPROBE_EXT_ZBKX (1 << 9)
> +#define RISCV_HWPROBE_EXT_ZKND (1 << 10)
> +#define RISCV_HWPROBE_EXT_ZKNE (1 << 11)
> +#define RISCV_HWPROBE_EXT_ZKNH (1 << 12)
> +#define RISCV_HWPROBE_EXT_ZKR (1 << 13)
> +#define RISCV_HWPROBE_EXT_ZKSED (1 << 14)
> +#define RISCV_HWPROBE_EXT_ZKSH (1 << 15)
> +#define RISCV_HWPROBE_EXT_ZKT (1 << 16)
> #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/sys_riscv.c
> b/arch/riscv/kernel/sys_riscv.c
> index 26ef5526bfb4..df15926196b6 100644
> --- a/arch/riscv/kernel/sys_riscv.c
> +++ b/arch/riscv/kernel/sys_riscv.c
> @@ -145,20 +145,28 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe
> *pair,
> for_each_cpu(cpu, cpus) {
> struct riscv_isainfo *isainfo = &hart_isa[cpu];
>
> - if (riscv_isa_extension_available(isainfo->isa, ZBA))
> - pair->value |= RISCV_HWPROBE_EXT_ZBA;
> - else
> - missing |= RISCV_HWPROBE_EXT_ZBA;
> -
> - if (riscv_isa_extension_available(isainfo->isa, ZBB))
> - pair->value |= RISCV_HWPROBE_EXT_ZBB;
> - else
> - missing |= RISCV_HWPROBE_EXT_ZBB;
> -
> - if (riscv_isa_extension_available(isainfo->isa, ZBS))
> - pair->value |= RISCV_HWPROBE_EXT_ZBS;
> - else
> - missing |= RISCV_HWPROBE_EXT_ZBS;
> +#define SET_HWPROBE_EXT_PAIR(ext) \
> + do { \
> + if (riscv_isa_extension_available(isainfo->isa, ext)) \
> + pair->value |= RISCV_HWPROBE_EXT_## ext; \
> + else \
> + missing |= RISCV_HWPROBE_EXT_## ext; \
> + } while (false) \
> +
> + SET_HWPROBE_EXT_PAIR(ZBA);
> + SET_HWPROBE_EXT_PAIR(ZBB);
> + SET_HWPROBE_EXT_PAIR(ZBC);
> + SET_HWPROBE_EXT_PAIR(ZBS);
> + SET_HWPROBE_EXT_PAIR(ZBKB);
> + SET_HWPROBE_EXT_PAIR(ZBKC);
> + SET_HWPROBE_EXT_PAIR(ZBKX);
> + SET_HWPROBE_EXT_PAIR(ZKND);
> + SET_HWPROBE_EXT_PAIR(ZKNE);
> + SET_HWPROBE_EXT_PAIR(ZKNH);
> + SET_HWPROBE_EXT_PAIR(ZKR);

Does the presence of a HWPROBE_EXT bit imply that userspace software can
actually directly use the described feature? If so, we should probably
not set ZKR unless mseccfg.USEED=1.

-s

> + SET_HWPROBE_EXT_PAIR(ZKSED);
> + SET_HWPROBE_EXT_PAIR(ZKSH);
> + SET_HWPROBE_EXT_PAIR(ZKT);
> }
>
> /* Now turn off reporting features if any CPU is missing it. */
> --
> 2.41.0
>
>
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