target/arm: Handle no-execute for Realm and Root regimes

While Root and Realm may read and write data from other spaces,
neither may execute from other pa spaces.

This happens for Stage1 EL3, EL2, EL2&0, and Stage2 EL1&0.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230620124418.805717-14-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/ptw.c

@@ -943,7 +943,7 @@ static bool get_phys_addr_v6(CPUARMState *env, S1Translate *ptw,
  * @xn:      XN (execute-never) bits
  * @s1_is_el0: true if this is S2 of an S1+2 walk for EL0
  */
-static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
+static int get_S2prot_noexecute(int s2ap)
 {
     int prot = 0;
 
@@ -953,6 +953,12 @@ static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
     if (s2ap & 2) {
         prot |= PAGE_WRITE;
     }
+    return prot;
+}
+
+static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
+{
+    int prot = get_S2prot_noexecute(s2ap);
 
     if (cpu_isar_feature(any_tts2uxn, env_archcpu(env))) {
         switch (xn) {
@@ -1030,9 +1036,39 @@ static int get_S1prot(CPUARMState *env, ARMMMUIdx mmu_idx, bool is_aa64,
         }
     }
 
-    if (out_pa == ARMSS_NonSecure && in_pa == ARMSS_Secure &&
-        (env->cp15.scr_el3 & SCR_SIF)) {
-        return prot_rw;
+    if (in_pa != out_pa) {
+        switch (in_pa) {
+        case ARMSS_Root:
+            /*
+             * R_ZWRVD: permission fault for insn fetched from non-Root,
+             * I_WWBFB: SIF has no effect in EL3.
+             */
+            return prot_rw;
+        case ARMSS_Realm:
+            /*
+             * R_PKTDS: permission fault for insn fetched from non-Realm,
+             * for Realm EL2 or EL2&0.  The corresponding fault for EL1&0
+             * happens during any stage2 translation.
+             */
+            switch (mmu_idx) {
+            case ARMMMUIdx_E2:
+            case ARMMMUIdx_E20_0:
+            case ARMMMUIdx_E20_2:
+            case ARMMMUIdx_E20_2_PAN:
+                return prot_rw;
+            default:
+                break;
+            }
+            break;
+        case ARMSS_Secure:
+            if (env->cp15.scr_el3 & SCR_SIF) {
+                return prot_rw;
+            }
+            break;
+        default:
+            /* Input NonSecure must have output NonSecure. */
+            g_assert_not_reached();
+        }
     }
 
     /* TODO have_wxn should be replaced with
@@ -1601,12 +1637,16 @@ static bool get_phys_addr_lpae(CPUARMState *env, S1Translate *ptw,
         /*
          * R_GYNXY: For stage2 in Realm security state, bit 55 is NS.
          * The bit remains ignored for other security states.
+         * R_YMCSL: Executing an insn fetched from non-Realm causes
+         * a stage2 permission fault.
          */
         if (out_space == ARMSS_Realm && extract64(attrs, 55, 1)) {
             out_space = ARMSS_NonSecure;
+            result->f.prot = get_S2prot_noexecute(ap);
+        } else {
+            xn = extract64(attrs, 53, 2);
+            result->f.prot = get_S2prot(env, ap, xn, s1_is_el0);
         }
-        xn = extract64(attrs, 53, 2);
-        result->f.prot = get_S2prot(env, ap, xn, s1_is_el0);
     } else {
         int nse, ns = extract32(attrs, 5, 1);
         switch (out_space) {