[RFC PATCH] raid6: Add RISC-V SIMD syndrome and recovery calculations

[Conor Dooley]

On Fri, Dec 20, 2024 at 07:40:23PM +0800, Chunyan Zhang wrote:
> The assembly is originally based on the ARM NEON and int.uc, but uses
> RISC-V vector instructions to implement the RAID6 syndrome and
> recovery calculations.
> 
> The functions are tested on QEMU.
> 
> Signed-off-by: Chunyan Zhang <zhangchunyan at iscas.ac.cn>
> ---
>  include/linux/raid/pq.h |   4 +
>  lib/raid6/Makefile      |   3 +
>  lib/raid6/algos.c       |   8 +
>  lib/raid6/recov_rvv.c   | 229 +++++++++++++
>  lib/raid6/rvv.c         | 715 ++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 959 insertions(+)
>  create mode 100644 lib/raid6/recov_rvv.c
>  create mode 100644 lib/raid6/rvv.c
> 
> diff --git a/include/linux/raid/pq.h b/include/linux/raid/pq.h
> index 98030accf641..4c21f06c662a 100644
> --- a/include/linux/raid/pq.h
> +++ b/include/linux/raid/pq.h
> @@ -108,6 +108,9 @@ extern const struct raid6_calls raid6_vpermxor4;
>  extern const struct raid6_calls raid6_vpermxor8;
>  extern const struct raid6_calls raid6_lsx;
>  extern const struct raid6_calls raid6_lasx;
> +extern const struct raid6_calls raid6_rvvx1;
> +extern const struct raid6_calls raid6_rvvx2;
> +extern const struct raid6_calls raid6_rvvx4;
>  
>  struct raid6_recov_calls {
>  	void (*data2)(int, size_t, int, int, void **);
> @@ -125,6 +128,7 @@ extern const struct raid6_recov_calls raid6_recov_s390xc;
>  extern const struct raid6_recov_calls raid6_recov_neon;
>  extern const struct raid6_recov_calls raid6_recov_lsx;
>  extern const struct raid6_recov_calls raid6_recov_lasx;
> +extern const struct raid6_recov_calls raid6_recov_rvv;
>  
>  extern const struct raid6_calls raid6_neonx1;
>  extern const struct raid6_calls raid6_neonx2;
> diff --git a/lib/raid6/Makefile b/lib/raid6/Makefile
> index 29127dd05d63..e62fb7cd773e 100644
> --- a/lib/raid6/Makefile
> +++ b/lib/raid6/Makefile
> @@ -10,6 +10,9 @@ raid6_pq-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o \
>  raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o recov_neon.o recov_neon_inner.o
>  raid6_pq-$(CONFIG_S390) += s390vx8.o recov_s390xc.o
>  raid6_pq-$(CONFIG_LOONGARCH) += loongarch_simd.o recov_loongarch_simd.o
> +raid6_pq-$(CONFIG_RISCV_ISA_V) += rvv.o recov_rvv.o
> +CFLAGS_rvv.o += -march=rv64gcv
> +CFLAGS_recov_rvv.o += -march=rv64gcv

I'm curious - why do you need this when you're using .option arch,+v
below?

>  hostprogs	+= mktables
>  
> diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
> index cd2e88ee1f14..0a388a605131 100644
> --- a/lib/raid6/algos.c
> +++ b/lib/raid6/algos.c
> @@ -80,6 +80,11 @@ const struct raid6_calls * const raid6_algos[] = {
>  #ifdef CONFIG_CPU_HAS_LSX
>  	&raid6_lsx,
>  #endif
> +#endif
> +#ifdef CONFIG_RISCV_ISA_V
> +	&raid6_rvvx1,
> +	&raid6_rvvx2,
> +	&raid6_rvvx4,
>  #endif
>  	&raid6_intx8,
>  	&raid6_intx4,
> @@ -115,6 +120,9 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = {
>  #ifdef CONFIG_CPU_HAS_LSX
>  	&raid6_recov_lsx,
>  #endif
> +#endif
> +#ifdef CONFIG_RISCV_ISA_V
> +	&raid6_recov_rvv,
>  #endif
>  	&raid6_recov_intx1,
>  	NULL
> diff --git a/lib/raid6/recov_rvv.c b/lib/raid6/recov_rvv.c
> new file mode 100644
> index 000000000000..8ae74803ea7f
> --- /dev/null
> +++ b/lib/raid6/recov_rvv.c
> @@ -0,0 +1,229 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2024 Institute of Software, CAS.
> + * Author: Chunyan Zhang <zhangchunyan at iscas.ac.cn>
> + */
> +
> +#include <asm/simd.h>
> +#include <asm/vector.h>
> +#include <crypto/internal/simd.h>
> +#include <linux/raid/pq.h>
> +
> +static void __raid6_2data_recov_rvv(int bytes, u8 *p, u8 *q, u8 *dp,
> +			      u8 *dq, const u8 *pbmul,
> +			      const u8 *qmul)
> +{
> +	asm volatile (
> +		".option	push\n"
> +		".option	arch,+v\n"
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