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.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20180308130626.12393-4-peter.maydell@linaro.org

1 files changed, 24 insertions, 0 deletions

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 5d76844..2292ad9 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1702,6 +1702,27 @@ static void pxa270c5_initfn(Object *obj)
     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(Object *obj)
+{
+    ARMCPU *cpu = ARM_CPU(obj);
+
+    if (kvm_enabled()) {
+        kvm_arm_set_cpu_features_from_host(cpu);
+    } else {
+        cortex_a15_initfn(obj);
+        /* 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(Object *obj)
 {
@@ -1769,6 +1790,9 @@ static const ARMCPUInfo arm_cpus[] = {
     { .name = "pxa270-b1",   .initfn = pxa270b1_initfn },
     { .name = "pxa270-c0",   .initfn = pxa270c0_initfn },
     { .name = "pxa270-c5",   .initfn = pxa270c5_initfn },
+#ifndef TARGET_AARCH64
+    { .name = "max",         .initfn = arm_max_initfn },
+#endif
 #ifdef CONFIG_USER_ONLY
     { .name = "any",         .initfn = arm_any_initfn },
 #endif