[PATCH v2 2/9] lib: utils: fdt_helper: parse RISC-V Worlds per-hart WID properties
Pawandeep Oza
pawandeep.oza at oss.qualcomm.com
Thu Sep 3 14:15:16 PDT 2026
On Mon, Aug 17, 2026 at 2:05 AM Yu-Chien Peter Lin <peter.lin at sifive.com> wrote:
>
> Add fdt_parse_worlds_all_harts() to parse platform-defined DT
> properties in the /cpus/cpu at X:
> - riscv,pmwid: M-mode World ID
> - riscv,pmwidlist: bitmap of permitted M-mode WIDs
> - riscv,pmlwidlist: bitmap of permitted lower-privilege WIDs
> Initialize parsed values in sbi_hart_features with has_* presence
> flags.
>
> These platform-defined values serve as the root-of-trust constraints
> for per-domain WID assignment during domain creation and context
> switching.
>
> Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
> ---
> include/sbi/sbi_hart.h | 6 ++
> include/sbi_utils/fdt/fdt_helper.h | 2 +
> lib/utils/fdt/fdt_helper.c | 92 ++++++++++++++++++++++++++++++
> platform/generic/platform.c | 13 ++++-
> 4 files changed, 112 insertions(+), 1 deletion(-)
>
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index 2941809e..4fcf5372 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -135,6 +135,12 @@ struct sbi_hart_features {
> unsigned int pmp_log2gran;
> unsigned int mhpm_mask;
> unsigned int mhpm_bits;
> + u32 pmwid;
> + u64 pmwidlist;
> + u64 pmlwidlist;
> + bool has_pmwid;
> + bool has_pmwidlist;
> + bool has_pmlwidlist;
Oza: do you need these 3 booleans ?
you can find out from the value itslef ?
pmwidlist == 0 means not rpesent
pmlwidlist = 0 means not rpesent
and may be pmwid == UINT_MAX then not present ?
> };
>
> 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 747ba028..d6025705 100644
> --- a/lib/utils/fdt/fdt_helper.c
> +++ b/lib/utils/fdt/fdt_helper.c
> @@ -457,6 +457,98 @@ 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) {
> + 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]);
> + hfeatures->has_pmwidlist = true;
> + }
> +
> + 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]);
> + hfeatures->has_pmlwidlist = true;
> + }
> +
> + /* Sanity checks */
> + if (hfeatures->has_pmwidlist && !hfeatures->pmwidlist) {
> + sbi_printf("%s: hart%u riscv,pmwidlist is empty\n",
> + __func__, hartid);
> + return SBI_EINVAL;
> + }
> +
> +#if __riscv_xlen == 32
> + if (hfeatures->has_pmwidlist &&
> + (hfeatures->pmwidlist >> 32)) {
> + sbi_printf("%s: hart%u riscv,pmwidlist has bits beyond XLEN\n",
> + __func__, hartid);
> + return SBI_EINVAL;
> + }
> +
> + if (hfeatures->has_pmlwidlist &&
> + (hfeatures->pmlwidlist >> 32)) {
> + sbi_printf("%s: hart%u riscv,pmlwidlist has bits beyond XLEN\n",
> + __func__, hartid);
> + return SBI_EINVAL;
> + }
> +#endif
> +
> + if (hfeatures->has_pmwid &&
> + hfeatures->pmwid >= __riscv_xlen) {
> + sbi_printf("%s: hart%u riscv,pmwid (%u) exceeds max WID\n",
> + __func__, hartid, hfeatures->pmwid);
> + return SBI_EINVAL;
> + }
> +
> + if (hfeatures->has_pmwidlist && hfeatures->has_pmwid &&
> + !(hfeatures->pmwidlist & BIT_ULL(hfeatures->pmwid))) {
> + sbi_printf("%s: hart%u riscv,pmwid (%u) not in pmwidlist\n",
> + __func__, hartid, 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
>
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