[PATCH v3 3/9] lib: fdt_domain: parse domain WID properties
Anup Patel
anup at brainfault.org
Wed Oct 28 03:52:27 PDT 2026
On Tue, Oct 27, 2026 at 2:05 PM Yu-Chien Peter Lin <peter.lin at sifive.com> wrote:
>
> Add wid and widdeleg fields to struct sbi_domain to store the
> RISC-V Worlds mlwid and mwideleg CSR values for each domain.
> Also, parse the root and user-defined domains' WID during
> fdt_domains_populate().
>
> When Smlwid is implemented, the "wid" property is mandatory
> for all domains; fail domain population if it is missing.
>
> Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
> ---
> Change v2->v3:
> - Add validate_domain_wid() to check if 'wid' is specified when Smlwid
> extension is present; return SBI_EINVAL if missing.
> - Parse 'wid' and 'widdeleg' for the root domain via fdt_parse_root_domain().
> - Set root.widdeleg default to 0.
> ---
> include/sbi/sbi_domain.h | 6 +++
> lib/sbi/sbi_domain.c | 2 +
> lib/utils/fdt/fdt_domain.c | 84 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 92 insertions(+)
>
> diff --git a/include/sbi/sbi_domain.h b/include/sbi/sbi_domain.h
> index 56a21397..5a291d1f 100644
> --- a/include/sbi/sbi_domain.h
> +++ b/include/sbi/sbi_domain.h
> @@ -19,6 +19,8 @@
>
> struct sbi_scratch;
>
> +#define INVALID_WID ((unsigned int)~0U)
> +
> /** Domain access types */
> enum sbi_domain_access {
> SBI_DOMAIN_READ = (1UL << 0),
> @@ -218,6 +220,10 @@ struct sbi_domain {
> bool system_reset_allowed;
> /** Is domain allowed to suspend the system */
> bool system_suspend_allowed;
> + /** World ID for this domain (mlwid value) */
> + u32 wid;
> + /** World ID delegation bitmask for this domain (mwiddeleg value) */
> + u64 widdeleg;
> /** Identifies whether to include the firmware region */
> bool fw_region_inited;
> };
> diff --git a/lib/sbi/sbi_domain.c b/lib/sbi/sbi_domain.c
> index 42fe5632..be9020d0 100644
> --- a/lib/sbi/sbi_domain.c
> +++ b/lib/sbi/sbi_domain.c
> @@ -30,6 +30,8 @@ struct sbi_domain root = {
> .possible_harts = NULL,
> .system_reset_allowed = true,
> .system_suspend_allowed = true,
> + .wid = INVALID_WID,
> + .widdeleg = 0,
> .fw_region_inited = false,
> };
>
> diff --git a/lib/utils/fdt/fdt_domain.c b/lib/utils/fdt/fdt_domain.c
> index e4cce8c3..8ce03236 100644
> --- a/lib/utils/fdt/fdt_domain.c
> +++ b/lib/utils/fdt/fdt_domain.c
> @@ -13,6 +13,7 @@
> #include <sbi/sbi_console.h>
> #include <sbi/sbi_domain.h>
> #include <sbi/sbi_error.h>
> +#include <sbi/sbi_hart.h>
> #include <sbi/sbi_hartmask.h>
> #include <sbi/sbi_heap.h>
> #include <sbi/sbi_scratch.h>
> @@ -290,6 +291,42 @@ static int __fdt_parse_region(const void *fdt, int domain_offset,
> return 0;
> }
>
> +static void fdt_parse_domain_wid_props(const void *fdt, int offset,
> + struct sbi_domain *dom)
> +{
> + const fdt32_t *val;
> + int len;
> + u64 val64;
> +
> + val = fdt_getprop(fdt, offset, "wid", &len);
> + if (val && len == sizeof(fdt32_t)) {
> + dom->wid = fdt32_to_cpu(val[0]);
> + }
> +
> + val = fdt_getprop(fdt, offset, "widdeleg", &len);
> + if (val && (len == (2 * sizeof(fdt32_t)))) {
> + val64 = fdt32_to_cpu(val[0]);
> + val64 = (val64 << 32) | fdt32_to_cpu(val[1]);
> + dom->widdeleg = val64;
> + }
> +}
> +
> +static int validate_domain_wid(const struct sbi_domain *dom)
> +{
> + if (dom->wid != INVALID_WID)
> + return 0;
> +
> + if (sbi_hart_has_extension(sbi_scratch_thishart_ptr(),
> + SBI_HART_EXT_SMLWID)) {
> + sbi_printf("%s: domain \"%s\": missing \"wid\""
> + " property (required by Smlwid)\n",
> + __func__, dom->name);
> + return SBI_EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static int __fdt_parse_domain(const void *fdt, int domain_offset, void *opaque)
> {
> u32 val32;
> @@ -306,6 +343,7 @@ static int __fdt_parse_domain(const void *fdt, int domain_offset, void *opaque)
> dom = sbi_zalloc(sizeof(*dom));
> if (!dom)
> return SBI_ENOMEM;
> + dom->wid = INVALID_WID;
>
> preg.dom = dom;
> preg.region_count = 0;
> @@ -449,6 +487,12 @@ static int __fdt_parse_domain(const void *fdt, int domain_offset, void *opaque)
> }
> dom->next_mode = val32;
>
> + /* Read "wid" and "widdeleg" DT properties */
> + fdt_parse_domain_wid_props(fdt, domain_offset, dom);
> + err = validate_domain_wid(dom);
> + if (err)
> + goto fail_free_all;
> +
> /* Read "system-reset-allowed" DT property */
> if (fdt_get_property(fdt, domain_offset,
> "system-reset-allowed", NULL))
> @@ -477,12 +521,52 @@ fail_free_domain:
> return err;
> }
>
> +static int fdt_root_domain_offset(const void *fdt)
> +{
> + int offset;
> +
> + offset = fdt_path_offset(fdt, "/chosen");
> + if (offset < 0)
> + return offset;
> +
> + offset = fdt_node_offset_by_compatible(fdt, offset,
> + "opensbi,domain,config");
> + if (offset < 0)
> + return offset;
> +
> + return fdt_subnode_offset(fdt, offset, "root");
> +}
> +
> +static int fdt_parse_root_domain(const void *fdt)
> +{
> + int offset;
> +
> + if (fdt) {
> + offset = fdt_root_domain_offset(fdt);
> + if (offset >= 0)
> + fdt_parse_domain_wid_props(fdt, offset, &root);
> + }
> +
> + /*
> + * Ensure root domain has a valid WID
> + * even if FDT or root subnode is absent
> + */
> + return validate_domain_wid(&root);
> +}
> +
> int fdt_domains_populate(const void *fdt)
> {
> + int err;
> +
> /* Sanity checks */
> if (!fdt)
> return SBI_EINVAL;
>
> + /* Parse root domain config from "root" subnode */
> + err = fdt_parse_root_domain(fdt);
> + if (err)
> + return err;
> +
> /* Iterate over each domain in FDT and populate details */
> return fdt_iterate_each_domain_ro(fdt, NULL, __fdt_parse_domain);
In addition to these changes, I suggest having compatible
string set to "opensbi,domain,instance" for root domain DT
node as well. To handle this in parsing, you can skip "root"
DT node in fdt_iterate_each_domain().
Regards,
Anup
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