From 733d60e6d77dbbfd3748a33675ca71d54cf0039a Mon Sep 17 00:00:00 2001
From: Igor Mammedov <imammedo@redhat.com>
Date: Tue, 20 Mar 2018 13:12:37 -0400
Subject: [PATCH] vl.c: convert cpu_model to cpu type and set of global
 properties before machine_init()

All machines that support user specified cpu_model either call
cpu_generic_init() or cpu_class_by_name()/CPUClass::parse_features
to parse feature string and to get CPU type to create.

Which leads to code duplication and hard-codding default CPU model
within machine_foo_init() code. Which makes it impossible to
get CPU type before machine_init() is run.

So instead of setting default CPUs models and doing parsing in
target specific machine_foo_init() in various ways, provide
a generic data driven cpu_model parsing before machine_init()
is called.

in follow up per target patches, it will allow to:
* define default CPU type in consistent/generic manner
per machine type and drop custom code that fallbacks
to default if cpu_model is NULL
* drop custom features parsing in targets and do it
in centralized way.
* for cases of
cpu_generic_init(TYPE_BASE/DEFAULT_CPU, "some_cpu")
replace it with
cpu_create(machine->cpu_type) || cpu_create(TYPE_FOO)
depending if CPU type is user settable or not.
not doing useless parsing and clearly documenting where
CPU model is user settable or fixed one.

Patch allows machine subclasses to define default CPU type
per machine class at class_init() time and if that is set
generic code will parse cpu_model into a MachineState::cpu_type
which will be used to create CPUs for that machine instance
and allows gradual per board conversion.

Backports commit 6063d4c0f98b35a27ca018393d328a1825412a7e from qemu
---
 qemu/include/hw/boards.h | 6 ++++++
 qemu/vl.c                | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/qemu/include/hw/boards.h b/qemu/include/hw/boards.h
index ce9ba5d7..cf76a842 100644
--- a/qemu/include/hw/boards.h
+++ b/qemu/include/hw/boards.h
@@ -62,6 +62,10 @@ MachineClass *find_default_machine(struct uc_struct *uc, int arch);
 
 /**
  * MachineClass:
+ * @default_cpu_type:
+ *    specifies default CPU_TYPE, which will be used for parsing target
+ *    specific features and for creating CPUs if CPU name wasn't provided
+ *    explicitly at CLI
  * @minimum_page_bits:
  *    If non-zero, the board promises never to create a CPU with a page size
  *    smaller than this, so QEMU can use a more efficient larger page
@@ -91,6 +95,7 @@ struct MachineClass {
 
     int max_cpus;
     int is_default;
+    const char *default_cpu_type;
     int arch;
     int minimum_page_bits;
     bool has_hotpluggable_cpus;
@@ -108,6 +113,7 @@ struct MachineState {
     ram_addr_t ram_size;
     ram_addr_t maxram_size;
     const char *cpu_model;
+    const char *cpu_type;
     struct uc_struct *uc;
     AccelState *accelerator;
 };
diff --git a/qemu/vl.c b/qemu/vl.c
index 6df81831..b2b8d42f 100644
--- a/qemu/vl.c
+++ b/qemu/vl.c
@@ -164,6 +164,11 @@ int machine_initialize(struct uc_struct *uc)
 
     current_machine->cpu_model = NULL;
 
+    /* parse features once if machine provides default cpu_type */
+    if (machine_class->default_cpu_type) {
+        current_machine->cpu_type = machine_class->default_cpu_type;
+    }
+
     return machine_class->init(uc, current_machine);
 }