[PATCH 2/2] target/riscv: Allow UXL to be 3 in mstatus on rv128

[email protected] Wed, 29 Jul 2026 10:39:41 +0200
Newsgroups org.nongnu.qemu-riscv,org.nongnu.qemu-devel
Message-ID <[email protected]>
From: Frédéric Pétrot <[email protected]>

Valid UXL field values for mstatus were restricted to fix a
reported issue, but this inadvertently broke the experimental
rv128 support where a value of 3 validly represents 128-bit
execution.

Update the mstatus write logic to permit UXL=3 when running on
an rv128 CPU.

Fixes: dcd028517749 ("target/riscv: Apply UXL WARL handling to vsstatus")
Signed-off-by: Frédéric Pétrot <[email protected]>
---
 target/riscv/tcg/csr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/riscv/tcg/csr.c b/target/riscv/tcg/csr.c
index d834b77714..5eeb9f0e0f 100644
--- a/target/riscv/tcg/csr.c
+++ b/target/riscv/tcg/csr.c
@@ -2014,8 +2014,8 @@ static uint64_t riscv_write_uxl(CPURISCVState *env, uint64_t val,
     RISCVMXL xl = riscv_cpu_mxl(env);
     uint64_t uxl = get_field(val, field);
 
-    if (uxl == MXL_RV128) {
-        uxl = xl == MXL_RV128 ? MXL_RV64 : xl;
+    if (xl != MXL_RV128 && uxl == MXL_RV128) {
+        uxl = xl;
         val = set_field(val, field, uxl);
     }
 
-- 
2.43.0