Re: [Qemu-devel] [PATCH] target/i386: kvm: add VMX and SVM migration blockers

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

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> Nested VMX and SVM do not support live migration yet.  Add a blocker
> until that is worked out.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  target/i386/kvm.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index db1f4104b6..3b6fbd3f20 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -860,6 +860,8 @@ static int hyperv_init_vcpu(X86CPU *cpu)
>  }
>  
>  static Error *invtsc_mig_blocker;
> +static Error *vmx_mig_blocker;
> +static Error *svm_mig_blocker;
>  
>  #define KVM_MAX_CPUID_ENTRIES  100
>  
> @@ -1250,6 +1252,29 @@ int kvm_arch_init_vcpu(CPUState *cs)
>      if (c) {
>          has_msr_feature_control = !!(c->ecx & CPUID_EXT_VMX) ||
>                                    !!(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->features[FEAT_8000_0001_ECX] & CPUID_EXT3_SVM) && !svm_mig_blocker) {
> +        error_setg(&svm_mig_blocker,
> +                   "Nested SVM virtualization does not support live migration yet");
> +        r = migrate_add_blocker(svm_mig_blocker, &local_err);
> +        if (local_err) {
> +            error_report_err(local_err);
> +            error_free(svm_mig_blocker);
> +            return r;
> +        }

I think that's OK from a migration point of view; my only worry is if
people have nesting enabled by default.  On AMD isn't it common to have
it enabled by default in KVM? Especially if using -cpu host ?

Dave

>      }
>  
>      if (env->mcg_cap & MCG_LMCE_P) {
> -- 
> 2.19.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK