KVM: xen: Use static_call() for invoking kvm_x86_ops hooks

Use static_call() for invoking kvm_x86_ops function that already have a
defined static call, mostly as a step toward having _all_ calls to
kvm_x86_ops route through a static_call() in order to simplify auditing,
e.g. via grep, that all functions have an entry in kvm-x86-ops.h, but
also because there's no reason not to use a static_call().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220128005208.4008533-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/xen.c

@@ -732,7 +732,7 @@ int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
 		instructions[0] = 0xb8;
 
 		/* vmcall / vmmcall */
-		kvm_x86_ops.patch_hypercall(vcpu, instructions + 5);
+		static_call(kvm_x86_patch_hypercall)(vcpu, instructions + 5);
 
 		/* ret */
 		instructions[8] = 0xc3;
@@ -867,7 +867,7 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
 	vcpu->run->exit_reason = KVM_EXIT_XEN;
 	vcpu->run->xen.type = KVM_EXIT_XEN_HCALL;
 	vcpu->run->xen.u.hcall.longmode = longmode;
-	vcpu->run->xen.u.hcall.cpl = kvm_x86_ops.get_cpl(vcpu);
+	vcpu->run->xen.u.hcall.cpl = static_call(kvm_x86_get_cpl)(vcpu);
 	vcpu->run->xen.u.hcall.input = input;
 	vcpu->run->xen.u.hcall.params[0] = params[0];
 	vcpu->run->xen.u.hcall.params[1] = params[1];