[PATCH v2 1/9] lib: sbi_hart: detect RISC-V Worlds ISA extensions

[Yu-Chien Peter Lin]

Add CSR definitions for RISC-V Worlds (mwid, mlwid, mlwidlist,
mwiddeleg, slwid) and detect Worlds extensions via CSR probes
in hart_detect_features().

Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
---
 include/sbi/riscv_encoding.h | 12 ++++++++++++
 include/sbi/sbi_hart.h       | 10 ++++++++++
 lib/sbi/sbi_hart.c           | 26 ++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
index ffe7666c..e0262bfc 100644
--- a/include/sbi/riscv_encoding.h
+++ b/include/sbi/riscv_encoding.h
@@ -400,6 +400,9 @@
 /* Supervisor Resource Management Configuration CSRs */
 #define CSR_SRMCFG			0x181
 
+/* Supervisor lower-privilege mode World ID CSR (Sswid) */
+#define CSR_SLWID			0x190
+
 /* Machine-Level Control transfer records CSRs */
 #define CSR_MCTRCTL                     0x34e
 
@@ -520,6 +523,15 @@
 #define CSR_MTINST			0x34a
 #define CSR_MTVAL2			0x34b
 
+/* Machine World ID CSRs (Smwid, Smlwid, Smlwidlist, Smwiddeleg) */
+#define CSR_MLWID			0x390
+#define CSR_MWID			0x749
+#define CSR_MWIDDELEG			0x748
+#define CSR_MLWIDLIST			0x74A
+
+/* mwid lock bit */
+#define MWID_LOCK			(_UL(1) << (__riscv_xlen - 1))
+
 /* Machine Memory Protection */
 #define CSR_PMPCFG0			0x3a0
 #define CSR_PMPCFG1			0x3a1
diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 543393bb..2941809e 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -95,6 +95,16 @@ enum sbi_hart_extensions {
 	SBI_HART_EXT_F,
 	/** Hart has D extension */
 	SBI_HART_EXT_D,
+	/** Hart has Smwid extension */
+	SBI_HART_EXT_SMWID,
+	/** Hart has Smlwid extension */
+	SBI_HART_EXT_SMLWID,
+	/** Hart has Smlwidlist extension */
+	SBI_HART_EXT_SMLWIDLIST,
+	/** Hart has Smwiddeleg extension */
+	SBI_HART_EXT_SMWIDDELEG,
+	/** Hart has Sswid extension */
+	SBI_HART_EXT_SSWID,
 
 	/** Maximum index of Hart extension */
 	SBI_HART_EXT_MAX,
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index bee88557..f5f4062e 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -360,6 +360,11 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
 	__SBI_HART_EXT_DATA(v, SBI_HART_EXT_V),
 	__SBI_HART_EXT_DATA(f, SBI_HART_EXT_F),
 	__SBI_HART_EXT_DATA(d, SBI_HART_EXT_D),
+	__SBI_HART_EXT_DATA(smwid, SBI_HART_EXT_SMWID),
+	__SBI_HART_EXT_DATA(smlwid, SBI_HART_EXT_SMLWID),
+	__SBI_HART_EXT_DATA(smlwidlist, SBI_HART_EXT_SMLWIDLIST),
+	__SBI_HART_EXT_DATA(smwiddeleg, SBI_HART_EXT_SMWIDDELEG),
+	__SBI_HART_EXT_DATA(sswid, SBI_HART_EXT_SSWID),
 };
 
 _Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),
@@ -647,9 +652,30 @@ __pmp_skip:
 	/* Detect if hart support sdtrig (debug triggers) */
 	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
 			CSR_TSELECT, SBI_HART_EXT_SDTRIG);
+	/* Detect if hart supports Smwid */
+	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
+			CSR_MWID, SBI_HART_EXT_SMWID);
+	/* Detect if hart supports Smlwid */
+	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
+			CSR_MLWID, SBI_HART_EXT_SMLWID);
+	/* Detect if hart supports Smlwidlist */
+	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
+			CSR_MLWIDLIST, SBI_HART_EXT_SMLWIDLIST);
+	/* Detect if hart supports Smwiddeleg */
+	__check_ext_csr(SBI_HART_PRIV_VER_UNKNOWN,
+			CSR_MWIDDELEG, SBI_HART_EXT_SMWIDDELEG);
 
 #undef __check_ext_csr
 
+	/*
+	 * slwid traps on access when mwiddeleg=0 (reset state), so
+	 * Sswid presence is inferred from Smwiddeleg.
+	 */
+	if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMWIDDELEG)) {
+		__sbi_hart_update_extension(hfeatures,
+					    SBI_HART_EXT_SSWID, true);
+	}
+
 #define __check_csr_existence(__csr, __csr_id)				\
 	csr_read_allowed(__csr, &trap);					\
 	if (!trap.cause)						\
-- 
2.43.7