Re: [Qemu-devel] [PATCH v2] target/i386: kvm: add VMX migration blocker

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> Nested VMX does not support live migration yet.  Add a blocker
> until that is worked out.
> 
> Nested SVM only does not support it, but unfortunately it is
> enabled by default for -cpu host so we cannot really disable it.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

So I'm OK with this, but it does need a release note warning whenever it
goes in, because it'll surprise those who've already enabled nesting
but don't use it on all their VMs.


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  target/i386/kvm.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index f524e7d929..27dcca5365 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -854,6 +854,7 @@ static int hyperv_init_vcpu(X86CPU *cpu)
>  }
>  
>  static Error *invtsc_mig_blocker;
> +static Error *vmx_mig_blocker;
>  
>  #define KVM_MAX_CPUID_ENTRIES  100
>  
> @@ -1246,6 +1247,17 @@ int kvm_arch_init_vcpu(CPUState *cs)
>                                    !!(c->ecx & CPUID_EXT_SMX);
>      }
>  
> +    if ((env->features[FEAT_1_ECX] & CPUID_EXT_VMX) && !vmx_mig_blocker) {
> +        error_setg(&vmx_mig_blocker,
> +                   "Nested VMX virtualization does not support live migration yet");
> +        r = migrate_add_blocker(vmx_mig_blocker, &local_err);
> +        if (local_err) {
> +            error_report_err(local_err);
> +            error_free(vmx_mig_blocker);
> +            return r;
> +        }
> +    }
> +
>      if (env->mcg_cap & MCG_LMCE_P) {
>          has_msr_mcg_ext_ctl = has_msr_feature_control = true;
>      }
> -- 
> 2.19.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK