Re: [PATCH v3 2/6] RISC-V: add vector crypto extension validation checks

From: "Clément Léger" <cleger@rivosinc.com>
To: Conor Dooley <conor@kernel.org>, linux-riscv@lists.infradead.org
Cc: Conor Dooley <conor.dooley@microchip.com>,
	Eric Biggers <ebiggers@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Andy Chiu <andybnac@gmail.com>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/6] RISC-V: add vector crypto extension validation checks
Date: Thu, 6 Feb 2025 11:20:35 +0100	[thread overview]
Message-ID: <00dc2fb7-da9b-42c3-9c3b-47d917df7cf6@rivosinc.com> (raw)
In-Reply-To: <20250205-quench-entrench-09bed8c8c823@spud>

On 05/02/2025 17:05, Conor Dooley wrote:
> From: Conor Dooley <conor.dooley@microchip.com>
> 
> Using Clement's new validation callbacks, support checking that
> dependencies have been satisfied for the vector crpyto extensions.
> Currently riscv_isa_extension_available(<vector crypto>) will return
> true on systems that support the extensions but vector itself has been
> disabled by the kernel, adding validation callbacks will prevent such a
> scenario from occuring and make the behaviour of the extension detection
> functions more consistent with user expectations - it's not expected to
> have to check for vector AND the specific crypto extension.
> 
> The 1.0.0 Vector crypto spec states:
> 	The Zvknhb and Zvbc Vector Crypto Extensions --and accordingly
> 	the composite extensions Zvkn and Zvks-- require a Zve64x base,
> 	or application ("V") base Vector Extension. All of the other
> 	Vector Crypto Extensions can be built on any embedded (Zve*) or
> 	application ("V") base Vector Extension.
> and this could be used as the basis for checking that the correct base
> for individual crypto extensions, but that's not really the kernel's job
> in my opinion and it is sufficient to leave that sort of precision to
> the dt-bindings. The kernel only needs to make sure that vector, in some
> form, is available.
> 
> Since vector will now be disabled proactively, there's no need to clear
> the bit in elf_hwcap in riscv_fill_hwcap() any longer.

Hey Conor,

To which part of the commit does this refer to ?

> 
> Link: https://github.com/riscv/riscv-crypto/releases/tag/v1.0.0
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
>  arch/riscv/kernel/cpufeature.c | 49 +++++++++++++++++++++++-----------
>  1 file changed, 33 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 40a24b08d905..1c148ecea612 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -138,6 +138,23 @@ static int riscv_ext_vector_float_validate(const struct riscv_isa_ext_data *data
>  	return 0;
>  }
>  
> +static int riscv_ext_vector_crypto_validate(const struct riscv_isa_ext_data *data,
> +					    const unsigned long *isa_bitmap)
> +{
> +	if (!IS_ENABLED(CONFIG_RISCV_ISA_V))
> +		return -EINVAL;
> +
> +	/*
> +	 * It isn't the kernel's job to check that the binding is correct, so
> +	 * it should be enough to check that any of the vector extensions are
> +	 * enabled, which in-turn means that vector is usable in this kernel
> +	 */
> +	if (!__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZVE32X))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>  static int riscv_ext_zca_depends(const struct riscv_isa_ext_data *data,
>  				 const unsigned long *isa_bitmap)
>  {
> @@ -397,8 +414,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_DATA(zksed, RISCV_ISA_EXT_ZKSED),
>  	__RISCV_ISA_EXT_DATA(zksh, RISCV_ISA_EXT_ZKSH),
>  	__RISCV_ISA_EXT_DATA(ztso, RISCV_ISA_EXT_ZTSO),
> -	__RISCV_ISA_EXT_SUPERSET(zvbb, RISCV_ISA_EXT_ZVBB, riscv_zvbb_exts),
> -	__RISCV_ISA_EXT_DATA(zvbc, RISCV_ISA_EXT_ZVBC),
> +	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zvbb, RISCV_ISA_EXT_ZVBB, riscv_zvbb_exts, riscv_ext_vector_x_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvbc, RISCV_ISA_EXT_ZVBC, riscv_ext_vector_crypto_validate),
>  	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zve32f, RISCV_ISA_EXT_ZVE32F, riscv_zve32f_exts, riscv_ext_vector_float_validate),
>  	__RISCV_ISA_EXT_DATA_VALIDATE(zve32x, RISCV_ISA_EXT_ZVE32X, riscv_ext_vector_x_validate),
>  	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zve64d, RISCV_ISA_EXT_ZVE64D, riscv_zve64d_exts, riscv_ext_vector_float_validate),
> @@ -406,20 +423,20 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zve64x, RISCV_ISA_EXT_ZVE64X, riscv_zve64x_exts, riscv_ext_vector_x_validate),
>  	__RISCV_ISA_EXT_DATA(zvfh, RISCV_ISA_EXT_ZVFH),
>  	__RISCV_ISA_EXT_DATA(zvfhmin, RISCV_ISA_EXT_ZVFHMIN),
> -	__RISCV_ISA_EXT_DATA(zvkb, RISCV_ISA_EXT_ZVKB),
> -	__RISCV_ISA_EXT_DATA(zvkg, RISCV_ISA_EXT_ZVKG),
> -	__RISCV_ISA_EXT_BUNDLE(zvkn, riscv_zvkn_bundled_exts),
> -	__RISCV_ISA_EXT_BUNDLE(zvknc, riscv_zvknc_bundled_exts),
> -	__RISCV_ISA_EXT_DATA(zvkned, RISCV_ISA_EXT_ZVKNED),
> -	__RISCV_ISA_EXT_BUNDLE(zvkng, riscv_zvkng_bundled_exts),
> -	__RISCV_ISA_EXT_DATA(zvknha, RISCV_ISA_EXT_ZVKNHA),
> -	__RISCV_ISA_EXT_DATA(zvknhb, RISCV_ISA_EXT_ZVKNHB),
> -	__RISCV_ISA_EXT_BUNDLE(zvks, riscv_zvks_bundled_exts),
> -	__RISCV_ISA_EXT_BUNDLE(zvksc, riscv_zvksc_bundled_exts),
> -	__RISCV_ISA_EXT_DATA(zvksed, RISCV_ISA_EXT_ZVKSED),
> -	__RISCV_ISA_EXT_DATA(zvksh, RISCV_ISA_EXT_ZVKSH),
> -	__RISCV_ISA_EXT_BUNDLE(zvksg, riscv_zvksg_bundled_exts),
> -	__RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvkb, RISCV_ISA_EXT_ZVKB, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvkg, RISCV_ISA_EXT_ZVKG, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvkn, riscv_zvkn_bundled_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvknc, riscv_zvknc_bundled_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvkned, RISCV_ISA_EXT_ZVKNED, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvkng, riscv_zvkng_bundled_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvknha, RISCV_ISA_EXT_ZVKNHA, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvknhb, RISCV_ISA_EXT_ZVKNHB, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvks, riscv_zvks_bundled_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvksc, riscv_zvksc_bundled_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvksed, RISCV_ISA_EXT_ZVKSED, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvksh, RISCV_ISA_EXT_ZVKSH, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvksg, riscv_zvksg_bundled_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_DATA_VALIDATE(zvkt, RISCV_ISA_EXT_ZVKT, riscv_ext_vector_crypto_validate),

I'm not sure if I already made that comment, so here we go again.
Shouldn't Zvbb use riscv_ext_vector_crypto_validate() as well ?  The
spec states that Zvbb is a superset of Zvkb and Zvkb uses the
riscv_ext_vector_crypto_validate() validation callback. I guess Zvbc
should also use it based on your spec excerpt in the commmit log.

Thanks,

Clément

>  	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
>  	__RISCV_ISA_EXT_DATA(smmpm, RISCV_ISA_EXT_SMMPM),
>  	__RISCV_ISA_EXT_SUPERSET(smnpm, RISCV_ISA_EXT_SMNPM, riscv_xlinuxenvcfg_exts),

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv