target/arm: Support multiple EL change hooks

Backports commit 08267487c99e8150382420936ab72c1e0ad74ce3 from qemu

qemu/target/arm/cpu.c

@@ -49,13 +49,15 @@ static bool arm_cpu_has_work(CPUState *cs)
          | CPU_INTERRUPT_EXITTB);
 }
 
-void arm_register_el_change_hook(ARMCPU *cpu, ARMELChangeHook *hook,
+void arm_register_el_change_hook(ARMCPU *cpu, ARMELChangeHookFn *hook,
                                  void *opaque)
 {
-    /* We currently only support registering a single hook function */
+    ARMELChangeHook *entry = g_new0(ARMELChangeHook, 1);
-    assert(!cpu->el_change_hook);
+
-    cpu->el_change_hook = hook;
+    entry->hook = hook;
-    cpu->el_change_hook_opaque = opaque;
+    entry->opaque = opaque;
+
+    QLIST_INSERT_HEAD(&cpu->el_change_hooks, entry, node);
 }
 
 static void cp_reg_reset(gpointer key, gpointer value, gpointer opaque)
@@ -438,6 +440,8 @@ static void arm_cpu_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     cpu->cp_regs = g_hash_table_new_full(g_int_hash, g_int_equal,
                                          g_free, g_free);
 
+    QLIST_INIT(&cpu->el_change_hooks);
+
     /* This cpu-id-to-MPIDR affinity is used only for TCG; KVM will override it.
      * We don't support setting cluster ID ([16..23]) (known as Aff2
      * in later ARM ARM versions), or any of the higher affinity level fields,
@@ -531,7 +535,14 @@ static void arm_cpu_post_init(struct uc_struct *uc, Object *obj)
 static void arm_cpu_finalizefn(struct uc_struct *uc, Object *obj, void *opaque)
 {
     ARMCPU *cpu = ARM_CPU(uc, obj);
+    ARMELChangeHook *hook, *next;
+
     g_hash_table_destroy(cpu->cp_regs);
+
+    QLIST_FOREACH_SAFE(hook, &cpu->el_change_hooks, node, next) {
+        QLIST_REMOVE(hook, node);
+        g_free(hook);
+    }
 }
 
 static int arm_cpu_realizefn(struct uc_struct *uc, DeviceState *dev, Error **errp)

qemu/target/arm/cpu.h

@@ -639,12 +639,17 @@ typedef struct CPUARMState {
 } CPUARMState;
 
 /**
- * ARMELChangeHook:
+ * ARMELChangeHookFn:
  * type of a function which can be registered via arm_register_el_change_hook()
  * to get callbacks when the CPU changes its exception level or mode.
  */
-typedef void ARMELChangeHook(ARMCPU *cpu, void *opaque);
+typedef void ARMELChangeHookFn(ARMCPU *cpu, void *opaque);
-
+typedef struct ARMELChangeHook ARMELChangeHook;
+struct ARMELChangeHook {
+    ARMELChangeHookFn *hook;
+    void *opaque;
+    QLIST_ENTRY(ARMELChangeHook) node;
+};
 
 /* These values map onto the return values for
  * QEMU_PSCI_0_2_FN_AFFINITY_INFO */
@@ -814,8 +819,7 @@ typedef struct ARMCPU {
      */
     bool cfgend;
 
-    ARMELChangeHook *el_change_hook;
+    QLIST_HEAD(, ARMELChangeHook) el_change_hooks;
-    void *el_change_hook_opaque;
 
     int32_t node_id; /* NUMA node this CPU belongs to */
 } ARMCPU;
@@ -2854,12 +2858,8 @@ static inline AddressSpace *arm_addressspace(CPUState *cs, MemTxAttrs attrs)
  * CPU changes exception level or mode. The hook function will be
  * passed a pointer to the ARMCPU and the opaque data pointer passed
  * to this function when the hook was registered.
- *
- * Note that we currently only support registering a single hook function,
- * and will assert if this function is called twice.
- * This facility is intended for the use of the GICv3 emulation.
  */
-void arm_register_el_change_hook(ARMCPU *cpu, ARMELChangeHook *hook,
+void arm_register_el_change_hook(ARMCPU *cpu, ARMELChangeHookFn *hook,
                                  void *opaque);
 
 /**

qemu/target/arm/internals.h

@@ -729,11 +729,12 @@ void arm_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
                                    int mmu_idx, MemTxAttrs attrs,
                                    MemTxResult response, uintptr_t retaddr);
 
-/* Call the EL change hook if one has been registered */
+/* Call any registered EL change hooks */
 static inline void arm_call_el_change_hook(ARMCPU *cpu)
 {
-    if (cpu->el_change_hook) {
+    ARMELChangeHook *hook, *next;
-        cpu->el_change_hook(cpu, cpu->el_change_hook_opaque);
+    QLIST_FOREACH_SAFE(hook, &cpu->el_change_hooks, node, next) {
+        hook->hook(cpu, hook->opaque);
     }
 }