[PATCH v4 2/9] lib: utils: fdt_helper: parse RISC-V Worlds per-hart WID properties

[Yu-Chien Peter Lin <peter.lin@sifive.com>]

Extend fdt_parse_isa_extensions_all_harts() to also parse the
platform-defined RISC-V Worlds DT properties in /cpus/cpu@X:
- riscv,pmwid: M-mode World ID
- riscv,pmwidlist: bitmap of permitted M-mode WIDs
- riscv,pmlwidlist: bitmap of permitted lower-privilege WIDs
and store the parsed values in struct sbi_hart_features.

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@sifive.com>
---
Change v3->v4:
- Parse Worlds properties in fdt_parse_isa_extensions_all_harts()
  instead of a separate fdt_parse_worlds_all_harts() (Anup).
- Drop RB-tag from Oza
---
 include/sbi/sbi_hart.h     |  5 +++
 lib/utils/fdt/fdt_helper.c | 69 ++++++++++++++++++++++++++++++++++----
 2 files changed, 67 insertions(+), 7 deletions(-)

diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index ed344783..629e3f64 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -138,6 +138,11 @@ struct sbi_hart_features {
 	unsigned int mhpm_mask;
 	unsigned int mhpm_bits;
 	unsigned long expected_trap;
+	u32 pmwid;
+	u64 pmwidlist;
+	u64 pmlwidlist;
+	bool has_pmwid;
+	bool has_pmlwidlist;
 };
 
 extern unsigned long hart_features_offset;
diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
index 747ba028..fdd25648 100644
--- a/lib/utils/fdt/fdt_helper.c
+++ b/lib/utils/fdt/fdt_helper.c
@@ -442,16 +442,71 @@ int fdt_parse_isa_extensions_all_harts(const void *fdt)
 		if (val && len > 0) {
 			fdt_parse_isa_extensions_one_hart((const char *)val,
 							  hfeatures->extensions, len);
-			continue;
+		} else {
+			val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
+			if (!val || len <= 0)
+				return SBI_ENOENT;
+
+			err = fdt_parse_isa_one_hart((const char *)val,
+						     hfeatures->extensions);
+			if (err)
+				return err;
 		}
 
-		val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
-		if (!val || len <= 0)
-			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;
+		}
 
-		err = fdt_parse_isa_one_hart((const char *)val, hfeatures->extensions);
-		if (err)
-			return err;
+		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]);
+			if (!hfeatures->pmwidlist) {
+				sbi_printf("%s: hart%u riscv,pmwidlist is empty\n",
+					   __func__, hartid);
+				return SBI_EINVAL;
+			}
+		}
+
+		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 __riscv_xlen == 32
+		if (hfeatures->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->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;
-- 
2.43.7


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