From 7388fff0791e3855ea45a87cb7bac5849c52f455 Mon Sep 17 00:00:00 2001
From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 12 Mar 2018 09:47:18 -0400
Subject: [PATCH] target/arm: Add "-cpu max" support

Add support for "-cpu max" for ARM guests. This CPU type behaves
like "-cpu host" when KVM is enabled, and like a system CPU with
the maximum possible feature set otherwise. (Note that this means
it won't be migratable across versions, as we will likely add
features to it in future.)

Backports commit bab52d4bba3f22921a690a887b4bd0342f2754cd from qemu
---
 qemu/target/arm/cpu-qom.h |  2 ++
 qemu/target/arm/cpu.c     | 18 ++++++++++++++++++
 qemu/target/arm/cpu64.c   | 14 ++++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/qemu/target/arm/cpu-qom.h b/qemu/target/arm/cpu-qom.h
index bf6e2e7a..b0865c9f 100644
--- a/qemu/target/arm/cpu-qom.h
+++ b/qemu/target/arm/cpu-qom.h
@@ -30,6 +30,8 @@
 #define ARM_CPU_GET_CLASS(uc, obj) \
     OBJECT_GET_CLASS(uc, ARMCPUClass, (obj), TYPE_ARM_CPU)
 
+#define TYPE_ARM_MAX_CPU "max-" TYPE_ARM_CPU
+
 /**
  * ARMCPUClass:
  * @parent_realize: The parent class' realize handler.
diff --git a/qemu/target/arm/cpu.c b/qemu/target/arm/cpu.c
index 4a9d6bd8..576b1eba 100644
--- a/qemu/target/arm/cpu.c
+++ b/qemu/target/arm/cpu.c
@@ -1466,6 +1466,21 @@ static void pxa270c5_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     cpu->reset_sctlr = 0x00000078;
 }
 
+#ifndef TARGET_AARCH64
+/* -cpu max: if KVM is enabled, like -cpu host (best possible with this host);
+ * otherwise, a CPU with as many features enabled as our emulation supports.
+ * The version of '-cpu max' for qemu-system-aarch64 is defined in cpu64.c;
+ * this only needs to handle 32 bits.
+ */
+static void arm_max_initfn(struct uc_struct *uc, Object *obj, void *opaque)
+{
+    cortex_a15_initfn(uc, obj, opaque);
+    /* In future we might add feature bits here even if the
+     * real-world A15 doesn't implement them.
+     */
+}
+#endif
+
 #ifdef CONFIG_USER_ONLY
 static void arm_any_initfn(struct uc_struct *uc, Object *obj, void *opaque)
 {
@@ -1530,6 +1545,9 @@ static const ARMCPUInfo arm_cpus[] = {
     { "pxa270-b1",   pxa270b1_initfn },
     { "pxa270-c0",   pxa270c0_initfn },
     { "pxa270-c5",   pxa270c5_initfn },
+#ifndef TARGET_AARCH64
+    { "max",         arm_max_initfn },
+#endif
 #ifdef CONFIG_USER_ONLY
     { "any",         arm_any_initfn },
 #endif
diff --git a/qemu/target/arm/cpu64.c b/qemu/target/arm/cpu64.c
index 62ff6271..062747bc 100644
--- a/qemu/target/arm/cpu64.c
+++ b/qemu/target/arm/cpu64.c
@@ -190,6 +190,19 @@ static void aarch64_a53_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     define_arm_cp_regs(cpu, cortex_a57_a53_cp_reginfo);
 }
 
+/* -cpu max: if KVM is enabled, like -cpu host (best possible with this host);
+ * otherwise, a CPU with as many features enabled as our emulation supports.
+ * The version of '-cpu max' for qemu-system-arm is defined in cpu.c;
+ * this only needs to handle 64 bits.
+ */
+static void aarch64_max_initfn(struct uc_struct *uc, Object *obj, void *opaque)
+{
+    aarch64_a57_initfn(uc, obj, opaque);
+    /* In future we might add feature bits here even if the
+     * real-world A57 doesn't implement them.
+     */
+}
+
 // Unicorn: enabled for the general use-case as well.
 static void aarch64_any_initfn(struct uc_struct *uc, Object *obj, void *opaque)
 {
@@ -224,6 +237,7 @@ typedef struct ARMCPUInfo {
 static const ARMCPUInfo aarch64_cpus[] = {
     { "cortex-a57",  aarch64_a57_initfn },
     { "cortex-a53",  aarch64_a53_initfn },
+    { "max",         aarch64_max_initfn },
     // Unicorn: enabled for the general use case as well
     { "any",         aarch64_any_initfn },
     { NULL }