accel: introduce AccelCPUClass extending CPUClass

add a new optional interface to CPUClass, which allows accelerators
to extend the CPUClass with additional accelerator-specific
initializations.

This will allow to separate the target cpu code that is specific
to each accelerator, and register it automatically with object
hierarchy lookup depending on accelerator code availability,
as part of the accel_init_interfaces() initialization step.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Message-Id: <20210204163931.7358-19-cfontana@suse.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

2 files changed, 42 insertions, 0 deletions

diff --git a/include/hw/core/accel-cpu.h b/include/hw/core/accel-cpu.h
new file mode 100644
index 0000000000..24a6697412
--- /dev/null
+++ b/include/hw/core/accel-cpu.h
@@ -0,0 +1,38 @@
+/*
+ * Accelerator interface, specializes CPUClass
+ * This header is used only by target-specific code.
+ *
+ * Copyright 2021 SUSE LLC
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef ACCEL_CPU_H
+#define ACCEL_CPU_H
+
+/*
+ * This header is used to define new accelerator-specific target-specific
+ * accelerator cpu subclasses.
+ * It uses CPU_RESOLVING_TYPE, so this is clearly target-specific.
+ *
+ * Do not try to use for any other purpose than the implementation of new
+ * subclasses in target/, or the accel implementation itself in accel/
+ */
+
+#define TYPE_ACCEL_CPU "accel-" CPU_RESOLVING_TYPE
+#define ACCEL_CPU_NAME(name) (name "-" TYPE_ACCEL_CPU)
+typedef struct AccelCPUClass AccelCPUClass;
+DECLARE_CLASS_CHECKERS(AccelCPUClass, ACCEL_CPU, TYPE_ACCEL_CPU)
+
+typedef struct AccelCPUClass {
+    /*< private >*/
+    ObjectClass parent_class;
+    /*< public >*/
+
+    void (*cpu_class_init)(CPUClass *cc);
+    void (*cpu_instance_init)(CPUState *cpu);
+    void (*cpu_realizefn)(CPUState *cpu, Error **errp);
+} AccelCPUClass;
+
+#endif /* ACCEL_CPU_H */
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 4f6c6b18c9..38d813c389 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -79,6 +79,9 @@ struct TranslationBlock;
 /* see tcg-cpu-ops.h */
 struct TCGCPUOps;
 
+/* see accel-cpu.h */
+struct AccelCPUClass;
+
 /**
  * CPUClass:
  * @class_by_name: Callback to map -cpu command line model name to an
@@ -187,6 +190,7 @@ struct CPUClass {
     /* Keep non-pointer data at the end to minimize holes.  */
     int gdb_num_core_regs;
     bool gdb_stop_before_watchpoint;
+    struct AccelCPUClass *accel_cpu;
 
     /* when TCG is not available, this pointer is NULL */
     struct TCGCPUOps *tcg_ops;