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

Conor Dooley
2024-04-12T11:35:34Z

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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 <charlie@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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