[PATCH 2/3] target/riscv: Add step to validate 'B' extension

[Rob Bradford]

If the B extension is enabled warn if the user has disabled any of the
required extensions that are part of the 'B' extension. Conversely
enable the extensions that make up the 'B' extension if it is enabled.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
---
 target/riscv/tcg/tcg-cpu.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index fda54671d5..f10871d352 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -273,6 +273,35 @@ static void riscv_cpu_disable_priv_spec_isa_exts(RISCVCPU 
*cpu)
     }
 }
 
+static void riscv_cpu_validate_b(RISCVCPU *cpu)
+{
+    const char *warn_msg = "RVB mandates disabled extension %s";
+
+    if (!cpu->cfg.ext_zba) {
+        if (!cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zba))) {
+            cpu->cfg.ext_zba = true;
+        } else {
+            warn_report(warn_msg, "zba");
+        }
+    }
+
+    if (!cpu->cfg.ext_zbb) {
+        if (!cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zbb))) {
+            cpu->cfg.ext_zbb = true;
+        } else {
+            warn_report(warn_msg, "zbb");
+        }
+    }
+
+    if (!cpu->cfg.ext_zbs) {
+        if (!cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zbs))) {
+            cpu->cfg.ext_zbs = true;
+        } else {
+            warn_report(warn_msg, "zbs");
+        }
+    }
+}
+
 /*
  * Check consistency between chosen extensions while setting
  * cpu->cfg accordingly.
@@ -309,6 +338,10 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, 
Error **errp)
         env->misa_ext_mask |= RVI | RVM | RVA | RVF | RVD;
     }
 
+    if (riscv_has_ext(env, RVB)) {
+        riscv_cpu_validate_b(cpu);
+    }
+
     if (riscv_has_ext(env, RVI) && riscv_has_ext(env, RVE)) {
         error_setg(errp,
                    "I and E extensions are incompatible");
-- 
2.43.0