diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index baecfa7672..bf8e72a0e8 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -442,6 +442,35 @@ static void riscv_cpu_validate_g(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.
@@ -455,6 +484,10 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         riscv_cpu_validate_g(cpu);
     }
 
+    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");