target/riscv: introduce KVM AccelCPUClass

Add a KVM accelerator class like we did with TCG. The difference is
that, at least for now, we won't be using a realize() implementation for
this accelerator.

We'll start by assiging kvm_riscv_cpu_add_kvm_properties(), renamed to
kvm_cpu_instance_init(), as a 'cpu_instance_init' implementation. Change
riscv_cpu_post_init() to invoke accel_cpu_instance_init(), which will go
through the 'cpu_instance_init' impl of the current acceleration (if
available) and execute it. The end result is that the KVM initial setup,
i.e. starting registers and adding its specific properties, will be done
via this hook.

Add a 'tcg_enabled()' condition in riscv_cpu_post_init() to avoid
calling riscv_cpu_add_user_properties() when running KVM. We'll remove
this condition when the TCG accel class get its own 'cpu_instance_init'
implementation.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20230925175709.35696-12-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.c

@@ -1219,7 +1219,9 @@ static bool riscv_cpu_has_user_properties(Object *cpu_obj)
 
 static void riscv_cpu_post_init(Object *obj)
 {
-    if (riscv_cpu_has_user_properties(obj)) {
+    accel_cpu_instance_init(CPU(obj));
+
+    if (tcg_enabled() && riscv_cpu_has_user_properties(obj)) {
         riscv_cpu_add_user_properties(obj);
     }
 
@@ -1585,10 +1587,6 @@ static void riscv_cpu_add_multiext_prop_array(Object *obj,
 static void riscv_cpu_add_user_properties(Object *obj)
 {
 #ifndef CONFIG_USER_ONLY
-    if (kvm_enabled()) {
-        kvm_riscv_cpu_add_kvm_properties(obj);
-        return;
-    }
     riscv_add_satp_mode_properties(obj);
 #endif
 

target/riscv/kvm.c

@@ -31,6 +31,7 @@
 #include "sysemu/kvm_int.h"
 #include "cpu.h"
 #include "trace.h"
+#include "hw/core/accel-cpu.h"
 #include "hw/pci/pci.h"
 #include "exec/memattrs.h"
 #include "exec/address-spaces.h"
@@ -1318,8 +1319,9 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift,
     kvm_msi_via_irqfd_allowed = kvm_irqfds_enabled();
 }
 
-void kvm_riscv_cpu_add_kvm_properties(Object *obj)
+static void kvm_cpu_instance_init(CPUState *cs)
 {
+    Object *obj = OBJECT(RISCV_CPU(cs));
     DeviceState *dev = DEVICE(obj);
 
     riscv_init_user_properties(obj);
@@ -1331,7 +1333,7 @@ void kvm_riscv_cpu_add_kvm_properties(Object *obj)
     riscv_cpu_add_kvm_unavail_prop_array(obj, riscv_cpu_experimental_exts);
 
     for (Property *prop = riscv_cpu_options; prop && prop->name; prop++) {
-        /* Check if KVM created the property already */
+        /* Check if we have a specific KVM handler for the option */
         if (object_property_find(obj, prop->name)) {
             continue;
         }
@@ -1339,6 +1341,26 @@ void kvm_riscv_cpu_add_kvm_properties(Object *obj)
     }
 }
 
+static void kvm_cpu_accel_class_init(ObjectClass *oc, void *data)
+{
+    AccelCPUClass *acc = ACCEL_CPU_CLASS(oc);
+
+    acc->cpu_instance_init = kvm_cpu_instance_init;
+}
+
+static const TypeInfo kvm_cpu_accel_type_info = {
+    .name = ACCEL_CPU_NAME("kvm"),
+
+    .parent = TYPE_ACCEL_CPU,
+    .class_init = kvm_cpu_accel_class_init,
+    .abstract = true,
+};
+static void kvm_cpu_accel_register_types(void)
+{
+    type_register_static(&kvm_cpu_accel_type_info);
+}
+type_init(kvm_cpu_accel_register_types);
+
 static void riscv_host_cpu_init(Object *obj)
 {
     CPURISCVState *env = &RISCV_CPU(obj)->env;

target/riscv/kvm_riscv.h

@@ -19,7 +19,6 @@
 #ifndef QEMU_KVM_RISCV_H
 #define QEMU_KVM_RISCV_H
 
-void kvm_riscv_cpu_add_kvm_properties(Object *obj);
 void kvm_riscv_reset_vcpu(RISCVCPU *cpu);
 void kvm_riscv_set_irq(RISCVCPU *cpu, int irq, int level);
 void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift,