Re: [RFC PATCH v1 10/11] riscv: /proc/cpuinfo: Add rva23 bases to output

[Guodong Xu]

On Fri, Feb 6, 2026 at 8:24 AM Andrew Jones
<andrew.jones@xxxxxxxxxxxxxxxx> wrote:
>
> Output the rva23(u|s)64 ISA bases that the ISA extensions provide on
> new 'isa bases' lines both for the LCD of all harts and per hart, as
> shown in the example output below when booting qemu with
> -cpu rva23s64,sv39=on,pmp=on:
>
> processor       : 0
> hart            : 4
> isa bases       : rv64ima rva23u64
> isa             : rv64imafdcbvh_zicbom_zicbop_zicboz_ziccamoa_ziccif_zicclsm_ziccrse_zicntr_zicond_zicsr_zifencei_zihintntl_zihintpause_zihpm_zimop_za64rs_zaamo_zalrsc_zawrs_zfa_zfhmin_zca_zcb_zcd_zcmop_zba_zbb_zbs_zkt_zvbb_zve32f_zve32x_zve64d_zve64f_zve64x_zvfhmin_zvkb_zvkt_smaia_smnpm_smstateen_ssaia_sscofpmf_ssnpm_sstc_svade_svinval_svnapot_svpbmt
> mmu             : sv39
> mvendorid       : 0x0
> marchid         : 0x0
> mimpid          : 0x0
> hart isa bases  : rv64ima rva23u64
> hart isa        : rv64imafdcbvh_zicbom_zicbop_zicboz_ziccamoa_ziccif_zicclsm_ziccrse_zicntr_zicond_zicsr_zifencei_zihintntl_zihintpause_zihpm_zimop_za64rs_zaamo_zalrsc_zawrs_zfa_zfhmin_zca_zcb_zcd_zcmop_zba_zbb_zbs_zkt_zvbb_zve32f_zve32x_zve64d_zve64f_zve64x_zvfhmin_zvkb_zvkt_smaia_smnpm_smstateen_ssaia_sscofpmf_ssnpm_sstc_svade_svinval_svnapot_svpbmt
>
> Signed-off-by: Andrew Jones <andrew.jones@xxxxxxxxxxxxxxxx>
> ---
>  arch/riscv/include/asm/cpufeature.h | 10 ++++
>  arch/riscv/kernel/cpu.c             | 34 ++++++++++++
>  arch/riscv/kernel/cpufeature.c      | 83 +++++++++++++++++++++++++++++
>  3 files changed, 127 insertions(+)
>
> diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
> index 62837fa981e8..e750735c5686 100644
> --- a/arch/riscv/include/asm/cpufeature.h
> +++ b/arch/riscv/include/asm/cpufeature.h
> @@ -25,7 +25,15 @@ struct riscv_cpuinfo {
>         unsigned long mimpid;
>  };
>
> +enum {
> +       RISCV_ISA_BASE_IMA,
> +       RISCV_ISA_BASE_RVA23U64,
> +       RISCV_ISA_BASE_RVA23S64,
> +       RISCV_NR_ISA_BASES,
> +};
> +
>  struct riscv_isainfo {
> +       DECLARE_BITMAP(isa_bases, RISCV_NR_ISA_BASES);
>         DECLARE_BITMAP(isa, RISCV_ISA_EXT_MAX);
>  };
>
> @@ -152,4 +160,6 @@ static __always_inline bool riscv_cpu_has_extension_unlikely(int cpu, const unsi
>         return __riscv_isa_extension_available(hart_isa[cpu].isa, ext);
>  }
>
> +void riscv_set_isa_bases(unsigned long *isa_bases, const unsigned long *isa_bitmap);
> +
>  #endif
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index 3dbc8cc557dd..228867d7dc00 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -305,6 +305,34 @@ static void print_mmu(struct seq_file *f)
>         seq_printf(f, "mmu\t\t: %s\n", sv_type);
>  }
>
> +static DECLARE_BITMAP(riscv_isa_bases, RISCV_NR_ISA_BASES);
> +
> +static const char * const riscv_isa_base_names[] = {
> +#ifdef CONFIG_32BIT
> +       [RISCV_ISA_BASE_IMA] = "rv32ima",
> +#else
> +       [RISCV_ISA_BASE_IMA] = "rv64ima",
> +#endif
> +       [RISCV_ISA_BASE_RVA23U64] = "rva23u64",
> +       [RISCV_ISA_BASE_RVA23S64] = "rva23s64",
> +};
> +
> +static void print_isa_bases(struct seq_file *m,
> +                           const unsigned long *isa_bases,
> +                           const unsigned long *isa)
> +{
> +       unsigned int i;
> +
> +       if (bitmap_empty(isa_bases, RISCV_NR_ISA_BASES))
> +               riscv_set_isa_bases((unsigned long *)isa_bases, isa);
> +
> +       for (i = 0; i < RISCV_NR_ISA_BASES; i++) {
> +               if (test_bit(i, isa_bases))
> +                       seq_printf(m, " %s", riscv_isa_base_names[i]);
> +       }
> +       seq_puts(m, "\n");
> +}
> +
>  static void *c_start(struct seq_file *m, loff_t *pos)
>  {
>         if (*pos == nr_cpu_ids)
> @@ -336,6 +364,9 @@ static int c_show(struct seq_file *m, void *v)
>         seq_printf(m, "processor\t: %lu\n", cpu_id);
>         seq_printf(m, "hart\t\t: %lu\n", cpuid_to_hartid_map(cpu_id));
>
> +       seq_puts(m, "isa bases\t:");
> +       print_isa_bases(m, riscv_isa_bases, NULL);
> +
>         /*
>          * For historical raisins, the isa: line is limited to the lowest common
>          * denominator of extensions supported across all harts. A true list of
> @@ -360,6 +391,9 @@ static int c_show(struct seq_file *m, void *v)
>         seq_printf(m, "marchid\t\t: 0x%lx\n", ci->marchid);
>         seq_printf(m, "mimpid\t\t: 0x%lx\n", ci->mimpid);
>
> +       seq_puts(m, "hart isa bases\t:");
> +       print_isa_bases(m, hart_isa[cpu_id].isa_bases, hart_isa[cpu_id].isa);
> +
>         /*
>          * Print the ISA extensions specific to this hart, which may show
>          * additional extensions not present across all harts.
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index b001e78eecf6..07a42545e9e0 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -1262,3 +1262,86 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
>         }
>  }
>  #endif
> +
> +extern bool riscv_have_user_pmlen_7;
> +
> +void riscv_set_isa_bases(unsigned long *bases, const unsigned long *isa_bitmap)

I have no objection to the implementation of this function. My
concern is that, from looking at the patch, the only way to
trigger it is by cat /proc/cpuinfo, i.e., from print_isa_bases().

Shouldn't this be computed during init (e.g., in
riscv_fill_hwcap()) so the result is available to other
consumers like hwprobe?

> +{
> +       const unsigned long *isa = isa_bitmap ? isa_bitmap : riscv_isa;
> +       DECLARE_BITMAP(ext_mask, RISCV_ISA_EXT_MAX) = { 0 };
> +       DECLARE_BITMAP(tmp, RISCV_ISA_EXT_MAX);
> +
> +       /* IMA */
> +       set_bit(RISCV_ISA_EXT_I, ext_mask);
> +       set_bit(RISCV_ISA_EXT_M, ext_mask);
> +       set_bit(RISCV_ISA_EXT_A, ext_mask);
> +
> +       if (bitmap_andnot(tmp, ext_mask, isa, RISCV_ISA_EXT_MAX))
> +               return;
> +
> +       set_bit(RISCV_ISA_BASE_IMA, bases);
> +
> +       /* RVA23U64 */
> +
> +       /* Zic64b and Supm with PMLEN=7 */
> +       if (riscv_cbom_block_size != 64 ||
> +           riscv_cbop_block_size != 64 ||
> +           riscv_cboz_block_size != 64 ||
> +           !riscv_have_user_pmlen_7)
> +               return;
> +
> +       set_bit(RISCV_ISA_EXT_F, ext_mask);
> +       set_bit(RISCV_ISA_EXT_D, ext_mask);
> +       set_bit(RISCV_ISA_EXT_C, ext_mask);
> +       set_bit(RISCV_ISA_EXT_B, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICSR, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICNTR, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZIHPM, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICCIF, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICCRSE, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICCAMOA, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICCLSM, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZA64RS, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZIHINTPAUSE, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICBOM, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICBOP, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICBOZ, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZFHMIN, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZKT, ext_mask);
> +       set_bit(RISCV_ISA_EXT_V, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZVFHMIN, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZVBB, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZVKT, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZIHINTNTL, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZICOND, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZIMOP, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZCMOP, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZCB, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZFA, ext_mask);
> +       set_bit(RISCV_ISA_EXT_ZAWRS, ext_mask);
> +       set_bit(RISCV_ISA_EXT_SUPM, ext_mask);
> +
> +       if (bitmap_andnot(tmp, ext_mask, isa, RISCV_ISA_EXT_MAX))
> +               return;
> +
> +       set_bit(RISCV_ISA_BASE_RVA23U64, bases);
> +
> +       /* RVA23S64 */
> +       set_bit(RISCV_ISA_EXT_ZIFENCEI, ext_mask);
> +       /* TODO: Ss1p13 */
> +       /* Svbare, Sv39 -- assumed */
> +       set_bit(RISCV_ISA_EXT_SVADE, ext_mask);
> +       /* TODO: Ssccptr, Sstvecd, Sstvala, Sscounterenw */

For this,

> +       set_bit(RISCV_ISA_EXT_SVPBMT, ext_mask);
> +       set_bit(RISCV_ISA_EXT_SVINVAL, ext_mask);
> +       set_bit(RISCV_ISA_EXT_SVNAPOT, ext_mask);
> +       set_bit(RISCV_ISA_EXT_SSTC, ext_mask);
> +       set_bit(RISCV_ISA_EXT_SSCOFPMF, ext_mask);
> +       set_bit(RISCV_ISA_EXT_SSNPM, ext_mask);
> +       /* TODO: Ssu64xl */
> +       /* TODO: Sha = Ssstateen, Shcounterenw, Shvstvala, Shtvala, Shvstvecd, Shvsatpa, Shgatpa */

And this, these TODOs, I'd be happy if my patches 7 and 8 [1] can be
useful here.

Link: https://lore.kernel.org/all/20260207-isa-ext-parse-export-v1-7-a64d3a8bc20a@xxxxxxxxxxxx/
[1]

BR,
Guodong


> +       set_bit(RISCV_ISA_EXT_H, ext_mask);
> +
> +       if (/*TODO*/ false && !bitmap_andnot(tmp, ext_mask, isa, RISCV_ISA_EXT_MAX))
> +               set_bit(RISCV_ISA_BASE_RVA23S64, bases);
> +}
> --
> 2.43.0
>