On 24/04/20 13:37, Jon Doron wrote: > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index 435516595090..524b5466a515 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -1650,7 +1650,10 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa, > > bool kvm_hv_hypercall_enabled(struct kvm *kvm) > { > - return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE; > + struct kvm_hv *hv = &kvm->arch.hyperv; > + > + return READ_ONCE(hv->hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE || > + (hv->hv_syndbg.active && READ_ONCE(hv->hv_guest_os_id) != 0); > } Here too we could just shrug and allow hypercalls if the guest OS is not NULL. Paolo