linux-kernel - Re: [PATCH 1/7] RISC-V: Detect XVentanaCondOps from ISA string

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Message-ID: <20230919-bbcb3627b6d9d0238c5ba351@fedora>
Date:   Tue, 19 Sep 2023 08:26:18 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Anup Patel <apatel@...tanamicro.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Atish Patra <atishp@...shpatra.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Shuah Khan <shuah@...nel.org>,
        Andrew Jones <ajones@...tanamicro.com>,
        Mayuresh Chitale <mchitale@...tanamicro.com>,
        devicetree@...r.kernel.org, kvm@...r.kernel.org,
        kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 1/7] RISC-V: Detect XVentanaCondOps from ISA string

Hey Anup,

On Tue, Sep 19, 2023 at 09:23:37AM +0530, Anup Patel wrote:
> The Veyron-V1 CPU supports custom conditional arithmetic and
> conditional-select/move operations referred to as XVentanaCondOps
> extension. In fact, QEMU RISC-V also has support for emulating
> XVentanaCondOps extension.
> 
> Let us detect XVentanaCondOps extension from ISA string available
> through DT or ACPI.
> 
> Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> ---
>  Documentation/devicetree/bindings/riscv/extensions.yaml | 7 +++++++
>  arch/riscv/include/asm/hwcap.h                          | 1 +
>  arch/riscv/kernel/cpufeature.c                          | 1 +
>  3 files changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
> index 36ff6749fbba..cad8ef68eca7 100644
> --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> @@ -171,6 +171,13 @@ properties:
>              memory types as ratified in the 20191213 version of the privileged
>              ISA specification.
>  
> +        - const: xventanacondops
> +          description: |
> +            The Ventana specific XVentanaCondOps extension for conditional
> +            arithmetic and conditional-select/move operations defined by the
> +            Ventana custom extensions specification v1.0.1 (or higher) at
> +            https://github.com/ventanamicro/ventana-custom-extensions/releases.
> +

For this and the next patch, the binding change needs to be split out
from the code. checkpatch should've complained about it.

>          - const: zba
>            description: |
>              The standard Zba bit-manipulation extension for address generation
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 0f520f7d058a..b7efe9e2fa89 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -59,6 +59,7 @@
>  #define RISCV_ISA_EXT_ZIFENCEI		41
>  #define RISCV_ISA_EXT_ZIHPM		42
>  #define RISCV_ISA_EXT_SMSTATEEN		43
> +#define RISCV_ISA_EXT_XVENTANACONDOPS	44
>  
>  #define RISCV_ISA_EXT_MAX		64
>  
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 3755a8c2a9de..3a31d34fe709 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -182,6 +182,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
>  	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
>  	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> +	__RISCV_ISA_EXT_DATA(xventanacondops, RISCV_ISA_EXT_XVENTANACONDOPS),

I've been banging on for a bit about people doing weird stuff to detect
their vendor extensions, so nice to see it being done properly :)


Cheers,
Conor.

>  };
>  
>  const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
> -- 
> 2.34.1
> 

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