target/arm/ptw: Set s1ns bit in fault info more consistently

The s1ns bit in ARMMMUFaultInfo is documented as "true if
we faulted on a non-secure IPA while in secure state". Both the
places which look at this bit only do so after having confirmed
that this is a stage 2 fault and we're dealing with Secure EL2,
which leaves the ptw.c code free to set the bit to any random
value in the other cases.

Instead of taking advantage of that freedom, consistently
make the bit be set to false for the "not a stage 2 fault
for Secure EL2" cases. This removes some cases where we
were using an 'is_secure' boolean and leaving the reader
guessing about whether that was the right thing for Realm
and Root cases.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230807141514.19075-4-peter.maydell@linaro.org

target/arm/ptw.c

@@ -514,6 +514,17 @@ static ARMSecuritySpace S2_security_space(ARMSecuritySpace s1_space,
     }
 }
 
+static bool fault_s1ns(ARMSecuritySpace space, ARMMMUIdx s2_mmu_idx)
+{
+    /*
+     * For stage 2 faults in Secure EL22, S1NS indicates
+     * whether the faulting IPA is in the Secure or NonSecure
+     * IPA space. For all other kinds of fault, it is false.
+     */
+    return space == ARMSS_Secure && regime_is_stage2(s2_mmu_idx)
+        && s2_mmu_idx == ARMMMUIdx_Stage2_S;
+}
+
 /* Translate a S1 pagetable walk through S2 if needed.  */
 static bool S1_ptw_translate(CPUARMState *env, S1Translate *ptw,
                              hwaddr addr, ARMMMUFaultInfo *fi)
@@ -586,7 +597,7 @@ static bool S1_ptw_translate(CPUARMState *env, S1Translate *ptw,
             fi->s2addr = addr;
             fi->stage2 = true;
             fi->s1ptw = true;
-            fi->s1ns = !is_secure;
+            fi->s1ns = fault_s1ns(ptw->in_space, s2_mmu_idx);
             return false;
         }
     }
@@ -602,7 +613,7 @@ static bool S1_ptw_translate(CPUARMState *env, S1Translate *ptw,
     fi->s2addr = addr;
     fi->stage2 = regime_is_stage2(s2_mmu_idx);
     fi->s1ptw = fi->stage2;
-    fi->s1ns = !is_secure;
+    fi->s1ns = fault_s1ns(ptw->in_space, s2_mmu_idx);
     return false;
 }
 
@@ -729,7 +740,7 @@ static uint64_t arm_casq_ptw(CPUARMState *env, uint64_t old_val,
             fi->s2addr = ptw->out_virt;
             fi->stage2 = true;
             fi->s1ptw = true;
-            fi->s1ns = !ptw->in_secure;
+            fi->s1ns = fault_s1ns(ptw->in_space, ptw->in_ptw_idx);
             return 0;
         }
 
@@ -2030,7 +2041,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, S1Translate *ptw,
     fi->level = level;
     /* Tag the error as S2 for failed S1 PTW at S2 or ordinary S2.  */
     fi->stage2 = fi->s1ptw || regime_is_stage2(mmu_idx);
-    fi->s1ns = mmu_idx == ARMMMUIdx_Stage2;
+    fi->s1ns = fault_s1ns(ptw->in_space, mmu_idx);
     return true;
 }