Re: [RFC PATCH 02/12] lib: utils: fdt_helper: parse RISC-V Worlds DT properties

On Fri, Jun 26, 2026 at 3:16 AM Yu-Chien Peter Lin <[email protected]> wrote:
>
> Add fdt_parse_worlds_all_harts() to parse RISC-V Worlds device tree
> properties from CPU nodes:
>   - riscv,pmwid (u32): Physical Machine World ID for this hart
>   - riscv,pmwidlist (u64): Bitmap of permitted M-mode World IDs
>   - riscv,pmlwidlist (u64): Bitmap of permitted S/U-mode World IDs
>
> This patch extends the sbi_hart_features struct with new fields to
> store the parsed World ID configuration (has_pmwid, pmwid, pmwidlist,
> and pmlwidlist).
>
> Link: https://lore.kernel.org/all/[email protected]/
> Signed-off-by: Yu-Chien Peter Lin <[email protected]>
> ---
>  include/sbi/sbi_hart.h             | 15 ++++++++
>  include/sbi_utils/fdt/fdt_helper.h |  2 +
>  lib/utils/fdt/fdt_helper.c         | 61 ++++++++++++++++++++++++++++++
>  platform/generic/platform.c        | 13 ++++++-
>  4 files changed, 90 insertions(+), 1 deletion(-)
>
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index 2941809e..97072c09 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -135,6 +135,21 @@ struct sbi_hart_features {
>         unsigned int pmp_log2gran;
>         unsigned int mhpm_mask;
>         unsigned int mhpm_bits;
> +       /** True if riscv,pmwid was present in DT */
> +       bool has_pmwid;
> +       u32 pmwid;
> +       /**
> +        * Platform-defined bitmap of M-mode WIDs
> +        * (from DT riscv,pmwidlist). Zero means
> +        * absent/unrestricted.
> +        */
> +       u64 pmwidlist;
> +       /**
> +        * Platform-defined bitmap of S/U-mode WIDs
> +        * (from DT riscv,pmlwidlist). Zero means
> +        * absent/unrestricted.
> +        */
> +       u64 pmlwidlist;
>  };
>
>  extern unsigned long hart_features_offset;
> diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
> index 75a564d1..3f3d091b 100644
> --- a/include/sbi_utils/fdt/fdt_helper.h
> +++ b/include/sbi_utils/fdt/fdt_helper.h
> @@ -56,6 +56,8 @@ int fdt_parse_timebase_frequency(const void *fdt, unsigned long *freq);
>
>  int fdt_parse_isa_extensions_all_harts(const void *fdt);
>
> +int fdt_parse_worlds_all_harts(const void *fdt);
> +
>  int fdt_parse_gaisler_uart_node(const void *fdt, int nodeoffset,
>                                 struct platform_uart_data *uart);
>
> diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
> index ad4efaaf..8b40cd28 100644
> --- a/lib/utils/fdt/fdt_helper.c
> +++ b/lib/utils/fdt/fdt_helper.c
> @@ -457,6 +457,67 @@ int fdt_parse_isa_extensions_all_harts(const void *fdt)
>         return 0;
>  }
>
> +int fdt_parse_worlds_all_harts(const void *fdt)
> +{
> +       u32 hartid;
> +       const fdt32_t *val;
> +       struct sbi_scratch *scratch;
> +       struct sbi_hart_features *hfeatures;
> +       int err, cpu_offset, cpus_offset, len;
> +
> +       if (!fdt)
> +               return SBI_EINVAL;
> +
> +       cpus_offset = fdt_path_offset(fdt, "/cpus");
> +       if (cpus_offset < 0)
> +               return cpus_offset;
> +
> +       fdt_for_each_subnode(cpu_offset, fdt, cpus_offset) {
what about riscv,nworlds ? I think you should parse this and based on
that assume wid range - and rest of the wids should be rejected.
> +               err = fdt_parse_hart_id(fdt, cpu_offset, &hartid);
> +               if (err)
> +                       continue;
> +
> +               if (!fdt_node_is_enabled(fdt, cpu_offset))
> +                       continue;
> +
> +               scratch = sbi_hartid_to_scratch(hartid);
> +               if (!scratch)
> +                       return SBI_ENOENT;
> +
> +               hfeatures = sbi_hart_features_ptr(scratch);
> +               if (!hfeatures)
> +                       return SBI_ENOENT;
> +
> +               val = fdt_getprop(fdt, cpu_offset, "riscv,pmwid", &len);
> +               if (val && len == sizeof(fdt32_t)) {
> +                       hfeatures->pmwid = fdt32_to_cpu(*val);
> +                       hfeatures->has_pmwid = true;
> +               }
> +
> +               val = fdt_getprop(fdt, cpu_offset, "riscv,pmwidlist", &len);
> +               if (val && len == 2 * sizeof(fdt32_t)) {
> +                       hfeatures->pmwidlist = ((u64)fdt32_to_cpu(val[0]) << 32) |
> +                                               fdt32_to_cpu(val[1]);
> +               }
Oza: provide some defines for magic numbers.
> +
> +               val = fdt_getprop(fdt, cpu_offset, "riscv,pmlwidlist", &len);
> +               if (val && len == 2 * sizeof(fdt32_t)) {
> +                       hfeatures->pmlwidlist = ((u64)fdt32_to_cpu(val[0]) << 32) |
> +                                                fdt32_to_cpu(val[1]);
> +               }
> +
> +               /* Sanity checks */
> +               if (hfeatures->has_pmwid && (hfeatures->pmwid >= 64))
Oza:  features->pmwid >=nworlds ?
> +                       return SBI_EINVAL;
> +               if (hfeatures->has_pmwid && hfeatures->pmwidlist &&
> +                   !(hfeatures->pmwidlist & BIT_ULL(hfeatures->pmwid))) {
> +                       return SBI_EINVAL;
> +               }
> +       }
> +
> +       return 0;
> +}
> +
>  static int fdt_parse_uart_node_common(const void *fdt, int nodeoffset,
>                                       struct platform_uart_data *uart,
>                                       unsigned long default_freq,
> diff --git a/platform/generic/platform.c b/platform/generic/platform.c
> index 1df0280d..51e9f342 100644
> --- a/platform/generic/platform.c
> +++ b/platform/generic/platform.c
> @@ -255,11 +255,22 @@ int generic_final_init(bool cold_boot)
>
>  int generic_extensions_init(bool cold_boot)
>  {
> +       int rc;
> +
>         if (!cold_boot)
>                 return 0;
>
>         /* Parse the ISA string from FDT and enable the listed extensions */
> -       return fdt_parse_isa_extensions_all_harts(fdt_get_address());
> +       rc = fdt_parse_isa_extensions_all_harts(fdt_get_address());
> +       if (rc)
> +               return rc;
> +
> +       /* Parse RISC-V Worlds CPU properties from FDT */
> +       rc = fdt_parse_worlds_all_harts(fdt_get_address());
> +       if (rc)
> +               return rc;
> +
> +       return 0;
>  }
>
>  int generic_domains_init(void)
> --
> 2.43.7
>
>
> --
> opensbi mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/opensbi

-- 
opensbi mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/opensbi