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Date: Fri, 12 Apr 2024 12:34:01 +0100
From: Conor Dooley <conor.dooley@microchip.com>
To: Charlie Jenkins <charlie@rivosinc.com>
CC: Conor Dooley <conor@kernel.org>, Rob Herring <robh@kernel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Paul Walmsley
	<paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou
	<aou@eecs.berkeley.edu>, Guo Ren <guoren@kernel.org>, Conor Dooley
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	<cleger@rivosinc.com>, Jonathan Corbet <corbet@lwn.net>, Shuah Khan
	<shuah@kernel.org>, <linux-riscv@lists.infradead.org>,
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Subject: Re: [PATCH 14/19] riscv: hwprobe: Disambiguate vector and
 xtheadvector in hwprobe
Message-ID: <20240412-moonshine-acting-0df1a90b86d2@wendy>
References: <20240411-dev-charlie-support_thead_vector_6_9-v1-0-4af9815ec746@rivosinc.com>
 <20240411-dev-charlie-support_thead_vector_6_9-v1-14-4af9815ec746@rivosinc.com>
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In-Reply-To: <20240411-dev-charlie-support_thead_vector_6_9-v1-14-4af9815ec746@rivosinc.com>

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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.
>=20
> Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
>  arch/riscv/kernel/sys_hwprobe.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>=20
> diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwpr=
obe.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 |=3D RISCV_HWPROBE_IMA_C;
> =20
> -	if (has_vector())
> +	if (has_vector() && !riscv_has_vendor_extension_unlikely(RISCV_ISA_VEND=
OR_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 |=3D RISCV_HWPROBE_IMA_V;
> =20
>  	/*
> @@ -112,7 +112,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pa=
ir,
>  		EXT_KEY(ZACAS);
>  		EXT_KEY(ZICOND);
> =20
> -		if (has_vector()) {
> +		if (has_vector() && !riscv_has_vendor_extension_unlikely(RISCV_ISA_VEN=
DOR_EXT_XTHEADVECTOR)) {
>  			EXT_KEY(ZVBB);
>  			EXT_KEY(ZVBC);
>  			EXT_KEY(ZVKB);
>=20
> --=20
> 2.44.0
>=20

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