diff --git a/target-arm/helper.c b/target-arm/helper.c
index 86d0baf2c0..8603660d4f 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -1844,6 +1844,14 @@ static void ats_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
     A32_BANKED_CURRENT_REG_SET(env, par, par64);
 }
 
+static CPAccessResult at_s1e2_access(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+    if (arm_current_el(env) == 3 && !(env->cp15.scr_el3 & SCR_NS)) {
+        return CP_ACCESS_TRAP;
+    }
+    return CP_ACCESS_OK;
+}
+
 static void ats_write64(CPUARMState *env, const ARMCPRegInfo *ri,
                         uint64_t value)
 {
@@ -1871,10 +1879,10 @@ static void ats_write64(CPUARMState *env, const ARMCPRegInfo *ri,
         mmu_idx = secure ? ARMMMUIdx_S1SE0 : ARMMMUIdx_S1NSE0;
         break;
     case 4: /* AT S12E1R, AT S12E1W */
-        mmu_idx = ARMMMUIdx_S12NSE1;
+        mmu_idx = secure ? ARMMMUIdx_S1SE1 : ARMMMUIdx_S12NSE1;
         break;
     case 6: /* AT S12E0R, AT S12E0W */
-        mmu_idx = ARMMMUIdx_S12NSE0;
+        mmu_idx = secure ? ARMMMUIdx_S1SE0 : ARMMMUIdx_S12NSE0;
         break;
     default:
         g_assert_not_reached();
@@ -2746,6 +2754,25 @@ static const ARMCPRegInfo v8_cp_reginfo[] = {
     { .name = "AT_S1E0W", .state = ARM_CP_STATE_AA64,
       .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 8, .opc2 = 3,
       .access = PL1_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    { .name = "AT_S12E1R", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 8, .opc2 = 4,
+      .access = PL2_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    { .name = "AT_S12E1W", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 8, .opc2 = 5,
+      .access = PL2_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    { .name = "AT_S12E0R", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 8, .opc2 = 6,
+      .access = PL2_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    { .name = "AT_S12E0W", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 8, .opc2 = 7,
+      .access = PL2_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    /* AT S1E2* are elsewhere as they UNDEF from EL3 if EL2 is not present */
+    { .name = "AT_S1E3R", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 6, .crn = 7, .crm = 8, .opc2 = 0,
+      .access = PL3_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    { .name = "AT_S1E3W", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 6, .crn = 7, .crm = 8, .opc2 = 1,
+      .access = PL3_W, .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
 #endif
     /* TLB invalidate last level of translation table walk */
     { .name = "TLBIMVALIS", .cp = 15, .opc1 = 0, .crn = 8, .crm = 3, .opc2 = 5,
@@ -3021,6 +3048,18 @@ static const ARMCPRegInfo el2_cp_reginfo[] = {
       .type = ARM_CP_NO_RAW, .access = PL2_W,
       .writefn = tlbi_aa64_vaa_write },
 #ifndef CONFIG_USER_ONLY
+    /* Unlike the other EL2-related AT operations, these must
+     * UNDEF from EL3 if EL2 is not implemented, which is why we
+     * define them here rather than with the rest of the AT ops.
+     */
+    { .name = "AT_S1E2R", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 4, .crn = 7, .crm = 8, .opc2 = 0,
+      .access = PL2_W, .accessfn = at_s1e2_access,
+      .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
+    { .name = "AT_S1E2W", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 4, .crn = 7, .crm = 8, .opc2 = 1,
+      .access = PL2_W, .accessfn = at_s1e2_access,
+      .type = ARM_CP_NO_RAW, .writefn = ats_write64 },
     { .name = "CNTHCTL_EL2", .state = ARM_CP_STATE_BOTH,
       .opc0 = 3, .opc1 = 4, .crn = 14, .crm = 1, .opc2 = 0,
       /* ARMv7 requires bit 0 and 1 to reset to 1. ARMv8 defines the