[RFC PATCH 02/12] lib: utils: fdt_helper: parse RISC-V Worlds DT properties
Pawandeep Oza
pawandeep.oza at oss.qualcomm.com
Wed Jul 8 17:42:44 PDT 2026
On Wed, Jul 8, 2026 at 5:36 PM Pawandeep Oza
<pawandeep.oza at oss.qualcomm.com> wrote:
>
> On Fri, Jun 26, 2026 at 3:16 AM Yu-Chien Peter Lin <peter.lin at sifive.com> 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/20260619105834.1277302-3-peter.lin@sifive.com/
> > Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
> > ---
> > 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;
Oza: pmlwidlist defines which WIDs M-mode is permitted to assign to
S-mode. But next-wid is never validated against it.
> > };
> >
> > 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;
> > + }
Oza: Nothing prevents assigning the same WID to both M-mode and S-mode
- should not be identical for both worlds.
> > +
> > + 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
> > opensbi at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi
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