Re: [PATCH v2 1/3] RISC-V: Detect and Enable Svadu Extension Support

[Andrew Jones]

On Fri, Sep 22, 2023 at 08:56:47AM +0000, Yong-Xuan Wang wrote:
> We detect Svadu extension support from DTB and add arch_has_hw_pte_young()
> to enable optimization in MGLRU and __wp_page_copy_user() if Svadu
> extension is available.
> 
> Co-developed-by: Jinyu Tang <tjytimi@xxxxxxx>
> Signed-off-by: Jinyu Tang <tjytimi@xxxxxxx>
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@xxxxxxxxxx>
> ---
>  arch/riscv/include/asm/csr.h     | 1 +
>  arch/riscv/include/asm/hwcap.h   | 1 +
>  arch/riscv/include/asm/pgtable.h | 6 ++++++
>  arch/riscv/kernel/cpufeature.c   | 1 +
>  4 files changed, 9 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> index 777cb8299551..10648b372a2a 100644
> --- a/arch/riscv/include/asm/csr.h
> +++ b/arch/riscv/include/asm/csr.h
> @@ -194,6 +194,7 @@
>  /* xENVCFG flags */
>  #define ENVCFG_STCE			(_AC(1, ULL) << 63)
>  #define ENVCFG_PBMTE			(_AC(1, ULL) << 62)
> +#define ENVCFG_HADE			(_AC(1, ULL) << 61)

This bit is named 'ADUE' in the spec. Why are we calling it HADE?

>  #define ENVCFG_CBZE			(_AC(1, UL) << 7)
>  #define ENVCFG_CBCFE			(_AC(1, UL) << 6)
>  #define ENVCFG_CBIE_SHIFT		4
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index b7b58258f6c7..1013661d6516 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -58,6 +58,7 @@
>  #define RISCV_ISA_EXT_ZICSR		40
>  #define RISCV_ISA_EXT_ZIFENCEI		41
>  #define RISCV_ISA_EXT_ZIHPM		42
> +#define RISCV_ISA_EXT_SVADU		43
>  
>  #define RISCV_ISA_EXT_MAX		64
>  
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index b2ba3f79cfe9..028b700cd27b 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -629,6 +629,12 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
>  	return __pgprot(prot);
>  }
>  
> +#define arch_has_hw_pte_young arch_has_hw_pte_young
> +static inline bool arch_has_hw_pte_young(void)
> +{
> +	return riscv_has_extension_unlikely(RISCV_ISA_EXT_SVADU);
> +}
> +
>  /*
>   * THP functions
>   */
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 1cfbba65d11a..ead378c04991 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -178,6 +178,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
>  	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
>  	__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
> +	__RISCV_ISA_EXT_DATA(svadu, RISCV_ISA_EXT_SVADU),
>  	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
>  	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
>  	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> -- 
> 2.17.1
>

Thanks,
drew