Re: [PATCH 14/19] riscv: hwprobe: Disambiguate vector and xtheadvector in hwprobe

[Conor Dooley]

On Thu, Apr 11, 2024 at 09:11:20PM -0700, Charlie Jenkins wrote:
> Ensure that hwprobe does not flag "v" when xtheadvector is present.
> 
> Signed-off-by: Charlie Jenkins <char...@rivosinc.com>
> ---
>  arch/riscv/kernel/sys_hwprobe.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
> index 8cae41a502dd..e0a42c851511 100644
> --- a/arch/riscv/kernel/sys_hwprobe.c
> +++ b/arch/riscv/kernel/sys_hwprobe.c
> @@ -69,7 +69,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
>       if (riscv_isa_extension_available(NULL, c))
>               pair->value |= RISCV_HWPROBE_IMA_C;
>  
> -     if (has_vector())
> +     if (has_vector() && 
> !riscv_has_vendor_extension_unlikely(RISCV_ISA_VENDOR_EXT_XTHEADVECTOR))

Hmm, I think this is "dangerous". has_vector() is used across the kernel
now in several places for the in-kernel vector. I don't think that
has_vector() should return true for the T-Head stuff given that &
has_vector() should represent the ratified spec. I'll have to think
about this one and how nasty this makes any of the save/restore code
etc.

>               pair->value |= RISCV_HWPROBE_IMA_V;
>  
>       /*
> @@ -112,7 +112,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
>               EXT_KEY(ZACAS);
>               EXT_KEY(ZICOND);
>  
> -             if (has_vector()) {
> +             if (has_vector() && 
> !riscv_has_vendor_extension_unlikely(RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) {
>                       EXT_KEY(ZVBB);
>                       EXT_KEY(ZVBC);
>                       EXT_KEY(ZVKB);
> 
> -- 
> 2.44.0
> 

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