linux-kernel - Re: [PATCH v3 03/20] riscv: add ISA extension parsing for scalar crypto

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Date:   Wed, 8 Nov 2023 15:17:43 +0000
From:   Conor Dooley <conor@...nel.org>
To:     Clément Léger <cleger@...osinc.com>
Cc:     linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Palmer Dabbelt <palmer@...osinc.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Albert Ou <aou@...s.berkeley.edu>,
        Jonathan Corbet <corbet@....net>,
        Andrew Jones <ajones@...tanamicro.com>,
        Evan Green <evan@...osinc.com>,
        Samuel Ortiz <sameo@...osinc.com>,
        Conor Dooley <conor.dooley@...rochip.com>
Subject: Re: [PATCH v3 03/20] riscv: add ISA extension parsing for scalar
 crypto

On Tue, Nov 07, 2023 at 11:55:39AM +0100, Clément Léger wrote:
> From: Evan Green <evan@...osinc.com>
> 
> The Scalar Crypto specification defines Zk as a shorthand for the
> Zkn, Zkr and Zkt extensions. The same follows for both Zkn, Zks and Zbk,
> which are all shorthands for various other extensions. The detailed
> breakdown can be found in their dt-binding entries.
> 
> Since Zkn also implies the Zbkb, Zbkc and Zbkx extensions, simply passing
> "zk" through a DT should enable all of Zbkb, Zbkc, Zbkx, Zkn, Zkr and Zkt.
> For example, setting the "riscv,isa" DT property to "rv64imafdc_zk"
> should generate the following cpuinfo output:
> "rv64imafdc_zicntr_zicsr_zifencei_zihpm_zbkb_zbkc_zbkx_zknd_zkne_zknh_zkr_zkt"
> 
> riscv_isa_ext_data grows a pair of new members, to permit setting the
> relevant bits for "bundled" extensions, both while parsing the ISA string
> and the new dedicated extension properties.
> 
> Co-developed-by: Conor Dooley <conor.dooley@...rochip.com>
> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
> Signed-off-by: Evan Green <evan@...osinc.com>
> Signed-off-by: Clément Léger <cleger@...osinc.com>

> +static void __init match_isa_ext(const struct riscv_isa_ext_data *ext, const char *name,
> +				 const char *name_end, struct riscv_isainfo *isainfo)
> +{
> +	if ((name_end - name == strlen(ext->name)) &&
> +	     !strncasecmp(name, ext->name, name_end - name)) {
> +		/*
> +		 * If this is a bundle, enable all the ISA extensions that
> +		 * comprise the bundle.
> +		 */
> +		if (ext->subset_ext_size) {
> +			for (int i = 0; i < ext->subset_ext_size; i++) {
> +				if (riscv_isa_extension_check(ext->subset_ext_ids[i]))
> +					set_bit(ext->subset_ext_ids[i], isainfo->isa);
> +			}
> +		}
> +

> +		if (riscv_isa_extension_check(ext->id))
> +			set_bit(ext->id, isainfo->isa);

Could you add a comment here please about how this is safe to do for the
bundle extensions?

Otherwise,
Acked-by: Conor Dooley <conor.dooley@...rochip.com>

Thanks,
Conor.

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