target/loongarch: Implement kvm_arch_handle_exit

Implement kvm_arch_handle_exit for loongarch. In this
function, the KVM_EXIT_LOONGARCH_IOCSR is handled,
we read or write the iocsr address space by the addr,
length and is_write argument in kvm_run.

Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: xianglai li <lixianglai@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20240105075804.1228596-8-zhaotianrui@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>

target/loongarch/kvm/kvm.c

@@ -723,7 +723,29 @@ bool kvm_arch_cpu_check_are_resettable(void)
 
 int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
 {
-    return 0;
+    int ret = 0;
+    LoongArchCPU *cpu = LOONGARCH_CPU(cs);
+    CPULoongArchState *env = &cpu->env;
+    MemTxAttrs attrs = {};
+
+    attrs.requester_id = env_cpu(env)->cpu_index;
+
+    trace_kvm_arch_handle_exit(run->exit_reason);
+    switch (run->exit_reason) {
+    case KVM_EXIT_LOONGARCH_IOCSR:
+        address_space_rw(&env->address_space_iocsr,
+                         run->iocsr_io.phys_addr,
+                         attrs,
+                         run->iocsr_io.data,
+                         run->iocsr_io.len,
+                         run->iocsr_io.is_write);
+        break;
+    default:
+        ret = -1;
+        warn_report("KVM: unknown exit reason %d", run->exit_reason);
+        break;
+    }
+    return ret;
 }
 
 void kvm_arch_accel_class_init(ObjectClass *oc)

target/loongarch/trace-events

@@ -11,3 +11,4 @@ kvm_failed_get_counter(const char *msg) "Failed to get counter from KVM: %s"
 kvm_failed_put_counter(const char *msg) "Failed to put counter into KVM: %s"
 kvm_failed_get_cpucfg(const char *msg) "Failed to get cpucfg from KVM: %s"
 kvm_failed_put_cpucfg(const char *msg) "Failed to put cpucfg into KVM: %s"
+kvm_arch_handle_exit(int num) "kvm arch handle exit, the reason number: %d"