Re: [PATCH 2/7] RISC-V: Detect Zicond from ISA string

From: Andrew Jones
Date: Wed Sep 20 2023 - 03:44:51 EST


On Tue, Sep 19, 2023 at 09:23:38AM +0530, Anup Patel wrote:
> The RISC-V integer conditional (Zicond) operation extension defines
> standard conditional arithmetic and conditional-select/move operations
> which are inspired from the XVentanaCondOps extension. In fact, QEMU
> RISC-V also has support for emulating Zicond extension.
>
> Let us detect Zicond extension from ISA string available through
> DT or ACPI.
>
> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/riscv/extensions.yaml | 6 ++++++
> arch/riscv/include/asm/hwcap.h | 1 +
> arch/riscv/kernel/cpufeature.c | 1 +
> 3 files changed, 8 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
> index cad8ef68eca7..7ea90e2dbc5b 100644
> --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> @@ -225,6 +225,12 @@ properties:
> ratified in the 20191213 version of the unprivileged ISA
> specification.
>
> + - const: zicond
> + description:
> + The standard Zicond extension for conditional arithmetic and
> + conditional-select/move operations as ratified in commit 8fb6694
> + ("Update Gemfile") of riscv-zicond.

As of yesterday, v1.0 of the spec points at commit 95cf1f9 ("Add changes
requested by Ved during signoff")

> +
> - const: zicsr
> description: |
> The standard Zicsr extension for control and status register
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index b7efe9e2fa89..15bafc02ffd4 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -60,6 +60,7 @@
> #define RISCV_ISA_EXT_ZIHPM 42
> #define RISCV_ISA_EXT_SMSTATEEN 43
> #define RISCV_ISA_EXT_XVENTANACONDOPS 44
> +#define RISCV_ISA_EXT_ZICOND 45
>
> #define RISCV_ISA_EXT_MAX 64
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 3a31d34fe709..49b6551f3347 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -174,6 +174,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
> __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
> __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
> __RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> + __RISCV_ISA_EXT_DATA(zicond, RISCV_ISA_EXT_ZICOND),

Zi extensions come before Zb extensions.

> __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> __RISCV_ISA_EXT_DATA(smstateen, RISCV_ISA_EXT_SMSTATEEN),
> __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
> --
> 2.34.1
>

Thanks,
drew