Re: [Qemu-devel] [PATCH 03/10] target-i386: cpu: move xcc->kvm_required check to realize time

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 9 Jun 2016 15:34:30 -0300
Eduardo Habkost <ehabkost@redhat.com> wrote:

> On Mon, Jun 06, 2016 at 05:16:45PM +0200, Igor Mammedov wrote:
> > it will allow to drop custom cpu_x86_init() and use
> > cpu_generic_init() insteadi, reducing cpu_x86_create()
> > to a simple 3-liner.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > Eduardo Habkost <ehabkost@redhat.com>  
> 
> This triggers an assert when trying to use -cpu host with TCG:
> 
>   # ./x86_64-softmmu/qemu-system-x86_64 -machine accel=tcg -cpu host -nographic
>   qemu-system-x86_64: /root/qemu/target-i386/cpu.c:1558: host_x86_cpu_initfn: Assertion `(kvm_allowed)' failed.
>   Aborted
This is not related to this patch and it was there before.

Maybe a separate patch saying that it replaces assert() in
host_x86_cpu_initfn() with error check and user friendly
error message at later stage.

> 
> I will squash the following fix in it:
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 3f886a5..dcbfa0b 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1555,16 +1555,17 @@ static void host_x86_cpu_initfn(Object *obj)
>      CPUX86State *env = &cpu->env;
>      KVMState *s = kvm_state;
>  
> -    assert(kvm_enabled());
> -
>      /* We can't fill the features array here because we don't know yet if
>       * "migratable" is true or false.
>       */
>      cpu->host_features = true;
>  
> -    env->cpuid_level = kvm_arch_get_supported_cpuid(s, 0x0, 0, R_EAX);
> -    env->cpuid_xlevel = kvm_arch_get_supported_cpuid(s, 0x80000000, 0, R_EAX);
> -    env->cpuid_xlevel2 = kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
> +    /* If KVM is disabled, x86_cpu_realizefn() will report an error later */
> +    if (kvm_enabled()) {
> +        env->cpuid_level = kvm_arch_get_supported_cpuid(s, 0x0, 0, R_EAX);
> +        env->cpuid_xlevel = kvm_arch_get_supported_cpuid(s, 0x80000000, 0, R_EAX);
> +        env->cpuid_xlevel2 = kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
> +    }
>  
>      object_property_set_bool(OBJECT(cpu), true, "pmu", &error_abort);
>  }
>