On Tue, Oct 21, 2014 at 11:00:45AM -0400, Wei Huang wrote:
> No AMD CPUs support hyperthreading. When users select threads>1 in
> -smp option, QEMU fixes it by adjusting CPUID_0000_0001_EBX and
> CPUID_8000_0008_ECX based on inputs (sockets, cores, threads);
> so guest VM can boot correctly. However it is still better to gives
> users a warning when such case happens.
>
> Signed-off-by: Wei Huang <w...@redhat.com>
> ---
[...]
> @@ -2742,6 +2745,20 @@ 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 fixes
> + * this issue by adjusting CPUID_0000_0001_EBX and CPUID_8000_0008_ECX
> + * based on inputs (sockets,cores,threads), it is still better to gives
> + * users a warning.
> + *
> + * NOTE: the following code has to follow qemu_init_vcpu(). Otherwise
> + * cs->nr_threads hasn't be populated yet and the checking is incorrect.
> + */
> + if (IS_AMD_CPU(env) && (cs->nr_threads > 1) && !ht_warned) {
We set CmpLegacy for all non-Intel CPU vendors (and that's what makes
Linux guests ignore HT). So I believe we should warn if
!IS_INTEL_CPU(env) instead of just when it's AMD.
> + error_report("AMD CPU doesn't support hyperthreading. Please
> configure"
> + " -smp options properly.");
> + ht_warned = true;
> + }
> +
> x86_cpu_apic_realize(cpu, &local_err);
> if (local_err != NULL) {
> goto out;
> --
> 1.8.3.1
>
--
Eduardo
