[PATCH v2 2/9] lib: utils: fdt_helper: parse RISC-V Worlds per-hart WID properties

[Yu-Chien Peter Lin]

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;
 };
 
 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