diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 7d4b6cecedd6..5c69dc838c9a 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -339,6 +339,24 @@ static RISCVException hmode32(CPURISCVState *env, int csrno)
 
 }
 
+static RISCVException umode(CPURISCVState *env, int csrno)
+{
+    if (riscv_has_ext(env, RVU)) {
+        return RISCV_EXCP_NONE;
+    }
+
+    return RISCV_EXCP_ILLEGAL_INST;
+}
+
+static RISCVException umode32(CPURISCVState *env, int csrno)
+{
+    if (riscv_cpu_mxl(env) != MXL_RV32) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    return umode(env, csrno);
+}
+
 /* Checks if PointerMasking registers could be accessed */
 static RISCVException pointer_masking(CPURISCVState *env, int csrno)
 {
@@ -3519,7 +3537,7 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_MEDELEG]     = { "medeleg",    any,   read_medeleg, write_medeleg },
     [CSR_MIE]         = { "mie",        any,   NULL, NULL,   rmw_mie       },
     [CSR_MTVEC]       = { "mtvec",      any,   read_mtvec,   write_mtvec   },
-    [CSR_MCOUNTEREN]  = { "mcounteren", any,   read_mcounteren,
+    [CSR_MCOUNTEREN]  = { "mcounteren", umode, read_mcounteren,
                           write_mcounteren                                 },
 
     [CSR_MSTATUSH]    = { "mstatush",   any32, read_mstatush,
@@ -3553,9 +3571,9 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_MIPH]     = { "miph",     aia_any32, NULL, NULL, rmw_miph     },
 
     /* Execution environment configuration */
-    [CSR_MENVCFG]  = { "menvcfg",  any,   read_menvcfg,  write_menvcfg,
+    [CSR_MENVCFG]  = { "menvcfg",  umode, read_menvcfg,  write_menvcfg,
                        .min_priv_ver = PRIV_VERSION_1_12_0              },
-    [CSR_MENVCFGH] = { "menvcfgh", any32, read_menvcfgh, write_menvcfgh,
+    [CSR_MENVCFGH] = { "menvcfgh", umode32, read_menvcfgh, write_menvcfgh,
                        .min_priv_ver = PRIV_VERSION_1_12_0              },
     [CSR_SENVCFG]  = { "senvcfg",  smode, read_senvcfg,  write_senvcfg,
                        .min_priv_ver = PRIV_VERSION_1_12_0              },