Re: [Qemu-devel] [PATCH 1/1] target-i386: prevent users from setting threads>1 for AMD CPUs

[Wei Huang <wei@redhat.com>]

Sorry, please skip this version. I am sending out a updated one.

-Wei

On 10/07/2014 02:17 PM, Wei Huang wrote:
> AMD CPU doesn't support hyperthreading. Even though QEMU fixes
> this issue by setting CPUID_0000_0001_EBX and CPUID_8000_0008_ECX
> via conversion, it is better to stop end-users in the first place
> with a warning message.
>
> Signed-off-by: Wei Huang <wei@redhat.com>
> ---
>   target-i386/cpu.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index e7bf9de..01bbcaf 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -2742,6 +2742,24 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
>       mce_init(cpu);
>       qemu_init_vcpu(cs);
>
> +    /* AMD CPU doesn't support hyperthreading. Even though QEMU does fix
> +     * this issue by setting CPUID_0000_0001_EBX and CPUID_8000_0008_ECX
> +     * correctly, it is still better to stop end-users in the first place
> +     * by giving out a warning message.
> +     *
> +     * NOTE: cs->nr_threads is initialized in qemu_init_vcpu(). So the
> +     * following code has to follow qemu_init_vcpu().
> +     */
> +    if (env->cpuid_vendor1 == CPUID_VENDOR_AMD_1 &&
> +        env->cpuid_vendor2 == CPUID_VENDOR_AMD_2 &&
> +        env->cpuid_vendor3 == CPUID_VENDOR_AMD_3 &&
> +        (cs->nr_threads > 1)) {
> +        error_setg(&local_err,
> +                   "AMD CPU doesn't support hyperthreading. Please configure "
> +                   "-smp options correctly.");
> +        goto out;
> +    }
> +
>       x86_cpu_apic_realize(cpu, &local_err);
>       if (local_err != NULL) {
>           goto out;
>