KVM: x86: Remove guest mode check from kvm_check_nested_events

A survey of the callsites reveals that they all ensure the vCPU is in
guest mode before calling kvm_check_nested_events. Remove this dead
code so that the only negative value this function returns (at the
moment) is -EBUSY.

Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20210604172611.281819-2-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -8625,9 +8625,6 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu)
 
 int kvm_check_nested_events(struct kvm_vcpu *vcpu)
 {
-	if (WARN_ON_ONCE(!is_guest_mode(vcpu)))
-		return -EIO;
-
 	if (kvm_check_request(KVM_REQ_TRIPLE_FAULT, vcpu)) {
 		kvm_x86_ops.nested_ops->triple_fault(vcpu);
 		return 1;