target-arm: Support multiple address spaces in page table walks

If we have a secure address space, use it in page table walks:
when doing the physical accesses to read descriptors, make them
through the correct address space.

(The descriptor reads are the only direct physical accesses
made in target-arm/ for CPUs which might have TrustZone.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>

target-arm/cpu.h

@@ -2003,6 +2003,15 @@ static inline int arm_asidx_from_attrs(CPUState *cs, MemTxAttrs attrs)
 {
     return attrs.secure ? ARMASIdx_S : ARMASIdx_NS;
 }
+
+/* Return the AddressSpace to use for a memory access
+ * (which depends on whether the access is S or NS, and whether
+ * the board gave us a separate AddressSpace for S accesses).
+ */
+static inline AddressSpace *arm_addressspace(CPUState *cs, MemTxAttrs attrs)
+{
+    return cpu_get_address_space(cs, arm_asidx_from_attrs(cs, attrs));
+}
 #endif
 
 #endif

target-arm/helper.c

@@ -6273,13 +6273,15 @@ static uint32_t arm_ldl_ptw(CPUState *cs, hwaddr addr, bool is_secure,
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
     MemTxAttrs attrs = {};
+    AddressSpace *as;
 
     attrs.secure = is_secure;
+    as = arm_addressspace(cs, attrs);
     addr = S1_ptw_translate(env, mmu_idx, addr, attrs, fsr, fi);
     if (fi->s1ptw) {
         return 0;
     }
-    return address_space_ldl(cs->as, addr, attrs, NULL);
+    return address_space_ldl(as, addr, attrs, NULL);
 }
 
 static uint64_t arm_ldq_ptw(CPUState *cs, hwaddr addr, bool is_secure,
@@ -6289,13 +6291,15 @@ static uint64_t arm_ldq_ptw(CPUState *cs, hwaddr addr, bool is_secure,
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
     MemTxAttrs attrs = {};
+    AddressSpace *as;
 
     attrs.secure = is_secure;
+    as = arm_addressspace(cs, attrs);
     addr = S1_ptw_translate(env, mmu_idx, addr, attrs, fsr, fi);
     if (fi->s1ptw) {
         return 0;
     }
-    return address_space_ldq(cs->as, addr, attrs, NULL);
+    return address_space_ldq(as, addr, attrs, NULL);
 }
 
 static bool get_phys_addr_v5(CPUARMState *env, uint32_t address,