[PATCH v3 4/6] lib: sbi: hart: Move device tree features detection before trap-based checks

[Evgeny Voevodin]

Smrnmi detection and enablement in the following commits will happen
before any trap-based mechanism. As it relies on device tree, move
sbi_platform_extensions_init() to the beginning of hart_detect_features().

Signed-off-by: Evgeny Voevodin <evvoevod at tenstorrent.com>
---
 lib/sbi/sbi_hart.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 4aefb759..781161e5 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -522,6 +522,16 @@ static int hart_detect_features(struct sbi_scratch *scratch)
 	hfeatures->mhpm_mask = 0;
 	hfeatures->priv_version = SBI_HART_PRIV_VER_UNKNOWN;
 
+	/*
+	 * Parse device tree extensions early, before any trap-based checks.
+	 * Needed to detect Smrnmi and install NMI handlers before CSR probes
+	 * that may trigger traps.
+	 */
+	rc = sbi_platform_extensions_init(sbi_platform_thishart_ptr(),
+					  hfeatures);
+	if (rc)
+		return rc;
+
 #define __check_hpm_csr(__csr, __mask) 					  \
 	oldval = csr_read_allowed(__csr, &trap);			  \
 	if (!trap.cause) {						  \
@@ -676,12 +686,6 @@ __pmp_skip:
 
 #undef __check_csr_existence
 
-	/* Let platform populate extensions */
-	rc = sbi_platform_extensions_init(sbi_platform_thishart_ptr(),
-					  hfeatures);
-	if (rc)
-		return rc;
-
 	/* Zicntr should only be detected using traps */
 	__sbi_hart_update_extension(hfeatures, SBI_HART_EXT_ZICNTR,
 			    sbi_hart_has_csr(scratch, SBI_HART_CSR_CYCLE) &&
-- 
2.43.0