KVM: VMX: Skip delta_tsc shift-and-divide if the dividend is zero

Ten percent of nothin' is... let me do the math here.  Nothin' into
nothin', carry the nothin'...

Cc: Wanpeng Li <wanpengli@tencent.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -7063,10 +7063,9 @@ static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
 
 	/* Convert to host delta tsc if tsc scaling is enabled */
 	if (vcpu->arch.tsc_scaling_ratio != kvm_default_tsc_scaling_ratio &&
-			u64_shl_div_u64(delta_tsc,
+	    delta_tsc && u64_shl_div_u64(delta_tsc,
 				kvm_tsc_scaling_ratio_frac_bits,
-				vcpu->arch.tsc_scaling_ratio,
-				&delta_tsc))
+				vcpu->arch.tsc_scaling_ratio, &delta_tsc))
 		return -ERANGE;
 
 	/*