Re: [RFC PATCH v3 20/28] target/arm: Set cortex-a57 as default cpu for KVM-only build

[Claudio Fontana]

On 1/13/23 15:04, Fabiano Rosas wrote:
> The cortex-a15 is not present anymore when CONFIG_TCG=n, so use the
> cortex-a57 as default cpu for KVM.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Our recommendation currently for KVM on ARM is to always use CPU="host", as 
named cpu models generally don't work (yet?) with KVM.

https://qemu-project.gitlab.io/qemu/system/arm/cpu-features.html

Should then "host" be the default for KVM if CONFIG_TCG=N or CONFIG_TCG=M and 
the TCG .so is not loaded?

Thanks,

Claudio

> ---
>  hw/arm/virt.c                  | 6 ++++++
>  tests/qtest/arm-cpu-features.c | 3 +--
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index ea2413a0ba..19854f4137 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -203,8 +203,10 @@ static const int a15irqmap[] = {
>  };
>  
>  static const char *valid_cpus[] = {
> +#ifdef CONFIG_TCG
>      ARM_CPU_TYPE_NAME("cortex-a7"),
>      ARM_CPU_TYPE_NAME("cortex-a15"),
> +#endif
>      ARM_CPU_TYPE_NAME("cortex-a35"),
>      ARM_CPU_TYPE_NAME("cortex-a53"),
>      ARM_CPU_TYPE_NAME("cortex-a55"),
> @@ -3003,7 +3005,11 @@ static void virt_machine_class_init(ObjectClass *oc, 
> void *data)
>      mc->minimum_page_bits = 12;
>      mc->possible_cpu_arch_ids = virt_possible_cpu_arch_ids;
>      mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
> +#ifdef CONFIG_TCG
>      mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
> +#else
> +    mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a57");
> +#endif
>      mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
>      mc->kvm_type = virt_kvm_type;
>      assert(!mc->get_hotplug_handler);
> diff --git a/tests/qtest/arm-cpu-features.c b/tests/qtest/arm-cpu-features.c
> index 8691802950..4be1415823 100644
> --- a/tests/qtest/arm-cpu-features.c
> +++ b/tests/qtest/arm-cpu-features.c
> @@ -507,8 +507,7 @@ static void test_query_cpu_model_expansion_kvm(const void 
> *data)
>          char *error;
>  
>          assert_error(qts, "cortex-a15",
> -            "We cannot guarantee the CPU type 'cortex-a15' works "
> -            "with KVM on this host", NULL);
> +            "The CPU type 'cortex-a15' is not a recognized ARM CPU type", 
> NULL);
>  
>          assert_has_feature_enabled(qts, "host", "aarch64");
>