Re: [PATCH v1] riscv: remove RISCV_ISA_EXT_BUNDLE[_VALIDATE]

[Jisheng Zhang <jszhang@kernel.org>]

On Fri, Nov 06, 2026 at 07:05:59PM +0000, Conor Dooley wrote:
> From: Conor Dooley <conor.dooley@microchip.com>
> 
> RISCV_ISA_EXT_BUNDLE actually made sense when it was originally added,
> since it presented a simple interface where users (be that in kernel or
> userspace via things they are presented by the kernel) would check the
> exact extension needed for a feature, rather than muddying the water
> with parent extensions. As a result, the kernel does not track the
> status of the parent extension in the bundle, nor expose it to
> userspace.
> 
> This is in comparison to RISCV_ISA_EXT_SUPERSET,
> where the parent extension provided some explicit value, and would have
> to be checked for itself for some potential feature, and therefore we
> actually track the status of both child and parent extensions, and let
> userspace detect them independently.
> 
> Since we added this stuff, there's been some retroactive extension
> releases by RVI that have made previous monolithic extensions into pure
> wrappers that we intended using RISCV_ISA_EXT_BUNDLE for. Since we
> previously tracked that as one extension, and exported it to users as
> one extension, we can't just use RISCV_ISA_EXT_BUNDLE, and have to use
> RISCV_ISA_EXT_SUPERSET instead and nobody seems to know what to use each
> actually for anymore.
> 
> Just delete RISCV_ISA_EXT_BUNDLE for the sake of consistency between
> things that were always a bundle from ratification and for those
> retroactively made into bundles, with the side benefit of being less
> confusing for those adding extensions to the kernel.
> 
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
> ---
> Not 100% on if my comments on the initial rationale are right, they're
> just my recollection...
> 
> This is a rebase of the rfc, I didn't change anything functionally I
> just ran it on a board in the interim.
> 
> Cheers,
> Conor
> 
> CC: Paul Walmsley <pjw@kernel.org>
> CC: Palmer Dabbelt <palmer@dabbelt.com>
> CC: Alexandre Ghiti <alex@ghiti.fr>
> CC: Conor Dooley <conor.dooley@microchip.com>
> CC: Jisheng Zhang <jszhang@kernel.org>
> CC: Andrew Jones <andrew.jones@linux.dev>
> CC: Charlie Jenkins <thecharlesjenkins@gmail.com>
> CC: Guodong Xu <guodong.xu@oss.qualcomm.com>
> CC: linux-riscv@lists.infradead.org
> CC: linux-kernel@vger.kernel.org
> ---
>  arch/riscv/include/asm/cpufeature.h |  8 ---
>  arch/riscv/include/asm/hwcap.h      | 13 +++-
>  arch/riscv/kernel/cpufeature.c      | 97 ++++++++++++++++-------------
>  3 files changed, 64 insertions(+), 54 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
> index 99799cc6c198..4be952a41bba 100644
> --- a/arch/riscv/include/asm/cpufeature.h
> +++ b/arch/riscv/include/asm/cpufeature.h
> @@ -58,14 +58,6 @@ void riscv_clear_hypervisor_csr(void);
>  #define __RISCV_ISA_EXT_DATA_VALIDATE(_name, _id, _validate) \
>  			_RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, _validate)
>  
> -/* Used to declare pure "lasso" extension (Zk for instance) */
> -#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
> -	_RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, \
> -			    ARRAY_SIZE(_bundled_exts), NULL)
> -#define __RISCV_ISA_EXT_BUNDLE_VALIDATE(_name, _bundled_exts, _validate) \
> -	_RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, \
> -			    ARRAY_SIZE(_bundled_exts), _validate)
> -
>  /* Used to declare extensions that are a superset of other extensions (Zvbb for instance) */
>  #define __RISCV_ISA_EXT_SUPERSET(_name, _id, _sub_exts) \
>  	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), NULL)
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index b5952db9259f..a1cf9a935519 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -126,10 +126,19 @@
>  #define RISCV_ISA_EXT_ZIC64B		116
>  #define RISCV_ISA_EXT_SV48		117
>  #define RISCV_ISA_EXT_SV57		118
> +#define RISCV_ISA_EXT_ZK		119
> +#define RISCV_ISA_EXT_ZKN		120
> +#define RISCV_ISA_EXT_ZKS		121
> +#define RISCV_ISA_EXT_ZVKN		122
> +#define RISCV_ISA_EXT_ZVKNC		123
> +#define RISCV_ISA_EXT_ZVKNG		124
> +#define RISCV_ISA_EXT_ZVKS		125
> +#define RISCV_ISA_EXT_ZVKSC		126
> +#define RISCV_ISA_EXT_ZVKSG		127
>  
> -#define RISCV_ISA_EXT_XLINUXENVCFG	127
> +#define RISCV_ISA_EXT_XLINUXENVCFG	255
>  
> -#define RISCV_ISA_EXT_MAX		128
> +#define RISCV_ISA_EXT_MAX		256
>  #define RISCV_ISA_EXT_INVALID		U32_MAX
>  
>  #ifdef CONFIG_RISCV_M_MODE
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 72bce616491f..b4ce5221a26c 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -340,14 +340,6 @@ static const unsigned int riscv_a_exts[] = {
>  	RISCV_ISA_EXT_ZALRSC,
>  };
>  
> -#define RISCV_ISA_EXT_ZKN	\
> -	RISCV_ISA_EXT_ZBKB,	\
> -	RISCV_ISA_EXT_ZBKC,	\
> -	RISCV_ISA_EXT_ZBKX,	\
> -	RISCV_ISA_EXT_ZKND,	\
> -	RISCV_ISA_EXT_ZKNE,	\
> -	RISCV_ISA_EXT_ZKNH
> -
>  static int riscv_ext_smcdeleg_validate(const struct riscv_isa_ext_data *data,
>  				       const unsigned long *isa_bitmap)
>  {
> @@ -369,60 +361,77 @@ static int riscv_ext_ssccfg_validate(const struct riscv_isa_ext_data *data,
>  	return -EPROBE_DEFER;
>  }
>  
> -static const unsigned int riscv_zk_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZKN,
> +static const unsigned int riscv_zk_sub_exts[] = {
> +	RISCV_ISA_EXT_ZBKB,
> +	RISCV_ISA_EXT_ZBKC,
> +	RISCV_ISA_EXT_ZBKX,
> +	RISCV_ISA_EXT_ZKND,
> +	RISCV_ISA_EXT_ZKNE,
> +	RISCV_ISA_EXT_ZKNH,
>  	RISCV_ISA_EXT_ZKR,
>  	RISCV_ISA_EXT_ZKT
>  };
>  
> -static const unsigned int riscv_zkn_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZKN
> +static const unsigned int riscv_zkn_sub_exts[] = {
> +	RISCV_ISA_EXT_ZBKB,
> +	RISCV_ISA_EXT_ZBKC,
> +	RISCV_ISA_EXT_ZBKX,
> +	RISCV_ISA_EXT_ZKND,
> +	RISCV_ISA_EXT_ZKNE,
> +	RISCV_ISA_EXT_ZKNH
>  };
>  
> -static const unsigned int riscv_zks_bundled_exts[] = {
> +static const unsigned int riscv_zks_sub_exts[] = {
>  	RISCV_ISA_EXT_ZBKB,
>  	RISCV_ISA_EXT_ZBKC,
>  	RISCV_ISA_EXT_ZKSED,
>  	RISCV_ISA_EXT_ZKSH
>  };
>  
> -#define RISCV_ISA_EXT_ZVKN	\
> -	RISCV_ISA_EXT_ZVKNED,	\
> -	RISCV_ISA_EXT_ZVKNHB,	\
> -	RISCV_ISA_EXT_ZVKB,	\
> -	RISCV_ISA_EXT_ZVKT
>  
> -static const unsigned int riscv_zvkn_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZVKN
> +static const unsigned int riscv_zvkn_sub_exts[] = {
> +	RISCV_ISA_EXT_ZVKNED,
> +	RISCV_ISA_EXT_ZVKNHB,
> +	RISCV_ISA_EXT_ZVKB,
> +	RISCV_ISA_EXT_ZVKT
>  };
>  
> -static const unsigned int riscv_zvknc_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZVKN,
> +static const unsigned int riscv_zvknc_sub_exts[] = {
> +	RISCV_ISA_EXT_ZVKNED,
> +	RISCV_ISA_EXT_ZVKNHB,
> +	RISCV_ISA_EXT_ZVKB,
> +	RISCV_ISA_EXT_ZVKT,
>  	RISCV_ISA_EXT_ZVBC
>  };
>  
> -static const unsigned int riscv_zvkng_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZVKN,
> +static const unsigned int riscv_zvkng_sub_exts[] = {
> +	RISCV_ISA_EXT_ZVKNED,
> +	RISCV_ISA_EXT_ZVKNHB,
> +	RISCV_ISA_EXT_ZVKB,
> +	RISCV_ISA_EXT_ZVKT,
>  	RISCV_ISA_EXT_ZVKG
>  };
>  
> -#define RISCV_ISA_EXT_ZVKS	\
> -	RISCV_ISA_EXT_ZVKSED,	\
> -	RISCV_ISA_EXT_ZVKSH,	\
> -	RISCV_ISA_EXT_ZVKB,	\
> +static const unsigned int riscv_zvks_sub_exts[] = {
> +	RISCV_ISA_EXT_ZVKSED,
> +	RISCV_ISA_EXT_ZVKSH,
> +	RISCV_ISA_EXT_ZVKB,
>  	RISCV_ISA_EXT_ZVKT
> -
> -static const unsigned int riscv_zvks_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZVKS
>  };
>  
> -static const unsigned int riscv_zvksc_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZVKS,
> +static const unsigned int riscv_zvksc_sub_exts[] = {
> +	RISCV_ISA_EXT_ZVKSED,
> +	RISCV_ISA_EXT_ZVKSH,
> +	RISCV_ISA_EXT_ZVKB,
> +	RISCV_ISA_EXT_ZVKT,
>  	RISCV_ISA_EXT_ZVBC
>  };
>  
> -static const unsigned int riscv_zvksg_bundled_exts[] = {
> -	RISCV_ISA_EXT_ZVKS,
> +static const unsigned int riscv_zvksg_sub_exts[] = {
> +	RISCV_ISA_EXT_ZVKSED,
> +	RISCV_ISA_EXT_ZVKSH,
> +	RISCV_ISA_EXT_ZVKB,
> +	RISCV_ISA_EXT_ZVKT,
>  	RISCV_ISA_EXT_ZVKG
>  };
>  
> @@ -606,13 +615,13 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_DATA(zbkc, RISCV_ISA_EXT_ZBKC),
>  	__RISCV_ISA_EXT_DATA(zbkx, RISCV_ISA_EXT_ZBKX),
>  	__RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> -	__RISCV_ISA_EXT_BUNDLE(zk, riscv_zk_bundled_exts),
> -	__RISCV_ISA_EXT_BUNDLE(zkn, riscv_zkn_bundled_exts),
> +	__RISCV_ISA_EXT_SUPERSET(zk, RISCV_ISA_EXT_ZK, riscv_zk_sub_exts),
> +	__RISCV_ISA_EXT_SUPERSET(zkn, RISCV_ISA_EXT_ZKN, riscv_zkn_sub_exts),
>  	__RISCV_ISA_EXT_DATA(zknd, RISCV_ISA_EXT_ZKND),
>  	__RISCV_ISA_EXT_DATA(zkne, RISCV_ISA_EXT_ZKNE),
>  	__RISCV_ISA_EXT_DATA(zknh, RISCV_ISA_EXT_ZKNH),
>  	__RISCV_ISA_EXT_DATA(zkr, RISCV_ISA_EXT_ZKR),
> -	__RISCV_ISA_EXT_BUNDLE(zks, riscv_zks_bundled_exts),
> +	__RISCV_ISA_EXT_SUPERSET(zks, RISCV_ISA_EXT_ZKS, riscv_zks_sub_exts),
>  	__RISCV_ISA_EXT_DATA(zkt, RISCV_ISA_EXT_ZKT),
>  	__RISCV_ISA_EXT_DATA(zksed, RISCV_ISA_EXT_ZKSED),
>  	__RISCV_ISA_EXT_DATA(zksh, RISCV_ISA_EXT_ZKSH),
> @@ -632,17 +641,17 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_DATA(zvfhmin, RISCV_ISA_EXT_ZVFHMIN),
>  	__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_SUPERSET_VALIDATE(zvkn, RISCV_ISA_EXT_ZVKN, riscv_zvkn_sub_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zvknc, RISCV_ISA_EXT_ZVKNC, riscv_zvknc_sub_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_SUPERSET_VALIDATE(zvkng, RISCV_ISA_EXT_ZVKNG, riscv_zvkng_sub_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_SUPERSET_VALIDATE(zvks, RISCV_ISA_EXT_ZVKS, riscv_zvks_sub_exts, riscv_ext_vector_crypto_validate),
> +	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zvksc, RISCV_ISA_EXT_ZVKSC, riscv_zvksc_sub_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_SUPERSET_VALIDATE(zvksg, RISCV_ISA_EXT_ZVKSG, riscv_zvksg_sub_exts, riscv_ext_vector_crypto_validate),
>  	__RISCV_ISA_EXT_DATA_VALIDATE(zvkt, RISCV_ISA_EXT_ZVKT, riscv_ext_vector_crypto_validate),
>  	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
>  	__RISCV_ISA_EXT_DATA_VALIDATE(smcdeleg, RISCV_ISA_EXT_SMCDELEG,
> -- 
> 2.53.0
>