[RFC PATCH 03/12] lib: sbi_hart: enforce riscv,pmwid for Worlds ISA

[Yu-Chien Peter Lin]

When Smwid/Smlwid extensions are detected during hart ISA detection,
the riscv,pmwid device tree property is required to specify the M-mode
WID default value.

Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
---
 lib/sbi/sbi_hart.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 0c584bfc..cb0c66ea 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -768,6 +768,19 @@ skip_smwiddeleg:
 	/* Mark hart feature detection done */
 	hfeatures->detected = true;
 
+	/*
+	 * Validate M-mode WID default value: if Worlds ISA extensions
+	 * are present, riscv,pmwid must exist in DT.
+	 */
+	if ((sbi_hart_has_extension(scratch, SBI_HART_EXT_SMWID) ||
+	     sbi_hart_has_extension(scratch, SBI_HART_EXT_SMLWID)) &&
+	     !hfeatures->has_pmwid) {
+		sbi_printf("WARNING: hart%u has Worlds ISA extension but DT "
+			   "lacks riscv,pmwid.\n",
+			   current_hartid());
+		return SBI_EINVAL;
+	}
+
 	/*
 	 * On platforms with Smepmp, the previous booting stage must
 	 * enter OpenSBI with mseccfg.MML == 0. This allows OpenSBI
-- 
2.43.7