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Date: Thu, 31 Aug 2017 18:06:10 +0200
From: Cornelia Huck <cohuck@redhat.com>
Message-ID: <20170831180610.50d089aa.cohuck@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v1 08/11] s390x: allow only 1 CPU with TCG
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To: David Hildenbrand <david@redhat.com>
Cc: qemu-devel@nongnu.org, Richard Henderson <richard.henderson@linaro.org>, Aurelien Jarno <aurelien@aurel32.net>, thuth@redhat.com, borntraeger@de.ibm.com, Alexander Graf <agraf@suse.de>

On Thu, 31 Aug 2017 17:33:13 +0200
David Hildenbrand <david@redhat.com> wrote:

> On 31.08.2017 17:07, Cornelia Huck wrote:

> > If we know that this can't work, it makes sense to stop immediately, no?  
> 
> Hmm, like that than?
> 
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index 18ed0c57e3..dae848fa5f 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -23,6 +23,7 @@
>  #include "hw/s390x/css.h"
>  #include "virtio-ccw.h"
>  #include "qemu/config-file.h"
> +#include "qemu/error-report.h"
>  #include "s390-pci-bus.h"
>  #include "hw/s390x/storage-keys.h"
>  #include "hw/s390x/storage-attributes.h"
> @@ -56,6 +57,12 @@ static void s390_init_cpus(MachineState *machine)
>      if (machine->cpu_model == NULL) {
>          machine->cpu_model = s390_default_cpu_model_name();
>      }
> +    if (tcg_enabled() && max_cpus > S390_TCG_MAX_CPUS) {
> +        error_report("Number of SMP CPUs requested (%d) exceeds max CPUs "
> +                     "supported by TCG (%d) on s390x", max_cpus,
> +                     S390_TCG_MAX_CPUS);
> +        exit(1);
> +    }
> 
>      ms->cpus = g_new0(S390CPU *, max_cpus);
> 
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index 7ed9103b33..4e1de2102d 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -210,6 +210,8 @@ static inline S390CPU
> *s390_env_get_cpu(CPUS390XState *env)
> 
>  #define ENV_OFFSET offsetof(S390CPU, env)
> 
> +#define S390_TCG_MAX_CPUS 1
> +
>  #ifndef CONFIG_USER_ONLY
>  extern const struct VMStateDescription vmstate_s390_cpu;
>  #endif
> 
> 

Looks good!