linux-kernel - Re: [PATCH v9 06/17] riscv: Add has_vector/riscv

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Date:   Tue, 14 Dec 2021 08:29:26 -0800 (PST)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     greentime.hu@...ive.com
CC:     Paul Walmsley <paul.walmsley@...ive.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        aou@...s.berkeley.edu
Subject:     Re: [PATCH v9 06/17] riscv: Add has_vector/riscv_vsize to save vector features.

On Tue, 09 Nov 2021 01:48:18 PST (-0800), greentime.hu@...ive.com wrote:
> This patch is used to detect vector support status of CPU and use
> riscv_vsize to save the size of all the vector registers. It assumes
> all harts has the same capabilities in SMP system.
>
> [guoren@...ux.alibaba.com: add has_vector checking]
> Signed-off-by: Greentime Hu <greentime.hu@...ive.com>
> Co-developed-by: Guo Ren <guoren@...ux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> Co-developed-by: Vincent Chen <vincent.chen@...ive.com>
> Signed-off-by: Vincent Chen <vincent.chen@...ive.com>

IMO those SOB flags are a bit out of order, but checkpatch isn't 
complaining so I'm not sure it matters.  Otherwise:

Reviewed-by: Palmer Dabbelt <palmer@...osinc.com>

> ---
>  arch/riscv/kernel/cpufeature.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 7069e55335d0..8e7557980faf 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -21,6 +21,11 @@ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
>  #ifdef CONFIG_FPU
>  __ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu);
>  #endif
> +#ifdef CONFIG_VECTOR
> +#include <asm/vector.h>
> +__ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_vector);
> +unsigned long riscv_vsize __read_mostly;
> +#endif
>
>  /**
>   * riscv_isa_extension_base() - Get base extension word
> @@ -149,4 +154,12 @@ void __init riscv_fill_hwcap(void)
>  	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
>  		static_branch_enable(&cpu_hwcap_fpu);
>  #endif
> +
> +#ifdef CONFIG_VECTOR
> +	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
> +		static_branch_enable(&cpu_hwcap_vector);
> +		/* There are 32 vector registers with vlenb length. */
> +		riscv_vsize = csr_read(CSR_VLENB) * 32;
> +	}
> +#endif
>  }