KVM: x86: remove KVM_X86_OP_NULL and mark optional kvm_x86_ops

The original use of KVM_X86_OP_NULL, which was to mark calls
that do not follow a specific naming convention, is not in use
anymore.  Instead, let's mark calls that are optional because
they are always invoked within conditionals or with static_call_cond.
Those that are _not_, i.e. those that are defined with KVM_X86_OP,
must be defined by both vendor modules or some kind of NULL pointer
dereference is bound to happen at runtime.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm-x86-ops.h

 /* SPDX-License-Identifier: GPL-2.0 */
-#if !defined(KVM_X86_OP) || !defined(KVM_X86_OP_NULL)
+#if !defined(KVM_X86_OP) || !defined(KVM_X86_OP_OPTIONAL)
 BUILD_BUG_ON(1)
 #endif
 
 /*
- * KVM_X86_OP() and KVM_X86_OP_NULL() are used to help generate
- * "static_call()"s. They are also intended for use when defining
- * the vmx/svm kvm_x86_ops. KVM_X86_OP() can be used for those
- * functions that follow the [svm|vmx]_func_name convention.
- * KVM_X86_OP_NULL() can leave a NULL definition for the
- * case where there is no definition or a function name that
- * doesn't match the typical naming convention is supplied.
+ * KVM_X86_OP() and KVM_X86_OP_OPTIONAL() are used to help generate
+ * both DECLARE/DEFINE_STATIC_CALL() invocations and
+ * "static_call_update()" calls.
+ *
+ * KVM_X86_OP_OPTIONAL() can be used for those functions that can have
+ * a NULL definition, for example if "static_call_cond()" will be used
+ * at the call sites.
  */
-KVM_X86_OP_NULL(hardware_enable)
-KVM_X86_OP_NULL(hardware_disable)
-KVM_X86_OP_NULL(hardware_unsetup)
+KVM_X86_OP(hardware_enable)
+KVM_X86_OP(hardware_disable)
+KVM_X86_OP(hardware_unsetup)
 KVM_X86_OP(has_emulated_msr)
 KVM_X86_OP(vcpu_after_set_cpuid)
 KVM_X86_OP(vm_init)
-KVM_X86_OP_NULL(vm_destroy)
+KVM_X86_OP_OPTIONAL(vm_destroy)
 KVM_X86_OP(vcpu_create)
 KVM_X86_OP(vcpu_free)
 KVM_X86_OP(vcpu_reset)
@@ -32,9 +32,9 @@ KVM_X86_OP(get_segment_base)
 KVM_X86_OP(get_segment)
 KVM_X86_OP(get_cpl)
 KVM_X86_OP(set_segment)
-KVM_X86_OP_NULL(get_cs_db_l_bits)
+KVM_X86_OP(get_cs_db_l_bits)
 KVM_X86_OP(set_cr0)
-KVM_X86_OP_NULL(post_set_cr3)
+KVM_X86_OP_OPTIONAL(post_set_cr3)
 KVM_X86_OP(is_valid_cr4)
 KVM_X86_OP(set_cr4)
 KVM_X86_OP(set_efer)
@@ -50,15 +50,15 @@ KVM_X86_OP(set_rflags)
 KVM_X86_OP(get_if_flag)
 KVM_X86_OP(flush_tlb_all)
 KVM_X86_OP(flush_tlb_current)
-KVM_X86_OP_NULL(tlb_remote_flush)
-KVM_X86_OP_NULL(tlb_remote_flush_with_range)
+KVM_X86_OP_OPTIONAL(tlb_remote_flush)
+KVM_X86_OP_OPTIONAL(tlb_remote_flush_with_range)
 KVM_X86_OP(flush_tlb_gva)
 KVM_X86_OP(flush_tlb_guest)
 KVM_X86_OP(vcpu_pre_run)
 KVM_X86_OP(vcpu_run)
-KVM_X86_OP_NULL(handle_exit)
-KVM_X86_OP_NULL(skip_emulated_instruction)
-KVM_X86_OP_NULL(update_emulated_instruction)
+KVM_X86_OP(handle_exit)
+KVM_X86_OP(skip_emulated_instruction)
+KVM_X86_OP_OPTIONAL(update_emulated_instruction)
 KVM_X86_OP(set_interrupt_shadow)
 KVM_X86_OP(get_interrupt_shadow)
 KVM_X86_OP(patch_hypercall)
@@ -72,22 +72,22 @@ KVM_X86_OP(get_nmi_mask)
 KVM_X86_OP(set_nmi_mask)
 KVM_X86_OP(enable_nmi_window)
 KVM_X86_OP(enable_irq_window)
-KVM_X86_OP(update_cr8_intercept)
+KVM_X86_OP_OPTIONAL(update_cr8_intercept)
 KVM_X86_OP(check_apicv_inhibit_reasons)
 KVM_X86_OP(refresh_apicv_exec_ctrl)
 KVM_X86_OP(hwapic_irr_update)
 KVM_X86_OP(hwapic_isr_update)
-KVM_X86_OP_NULL(guest_apic_has_interrupt)
+KVM_X86_OP_OPTIONAL(guest_apic_has_interrupt)
 KVM_X86_OP(load_eoi_exitmap)
 KVM_X86_OP(set_virtual_apic_mode)
-KVM_X86_OP_NULL(set_apic_access_page_addr)
+KVM_X86_OP_OPTIONAL(set_apic_access_page_addr)
 KVM_X86_OP(deliver_interrupt)
-KVM_X86_OP_NULL(sync_pir_to_irr)
+KVM_X86_OP_OPTIONAL(sync_pir_to_irr)
 KVM_X86_OP(set_tss_addr)
 KVM_X86_OP(set_identity_map_addr)
 KVM_X86_OP(get_mt_mask)
 KVM_X86_OP(load_mmu_pgd)
-KVM_X86_OP_NULL(has_wbinvd_exit)
+KVM_X86_OP(has_wbinvd_exit)
 KVM_X86_OP(get_l2_tsc_offset)
 KVM_X86_OP(get_l2_tsc_multiplier)
 KVM_X86_OP(write_tsc_offset)
@@ -95,35 +95,35 @@ KVM_X86_OP(write_tsc_multiplier)
 KVM_X86_OP(get_exit_info)
 KVM_X86_OP(check_intercept)
 KVM_X86_OP(handle_exit_irqoff)
-KVM_X86_OP_NULL(request_immediate_exit)
+KVM_X86_OP(request_immediate_exit)
 KVM_X86_OP(sched_in)
-KVM_X86_OP_NULL(update_cpu_dirty_logging)
-KVM_X86_OP_NULL(vcpu_blocking)
-KVM_X86_OP_NULL(vcpu_unblocking)
-KVM_X86_OP_NULL(pi_update_irte)
-KVM_X86_OP_NULL(pi_start_assignment)
-KVM_X86_OP_NULL(apicv_post_state_restore)
-KVM_X86_OP_NULL(dy_apicv_has_pending_interrupt)
-KVM_X86_OP_NULL(set_hv_timer)
-KVM_X86_OP_NULL(cancel_hv_timer)
+KVM_X86_OP_OPTIONAL(update_cpu_dirty_logging)
+KVM_X86_OP_OPTIONAL(vcpu_blocking)
+KVM_X86_OP_OPTIONAL(vcpu_unblocking)
+KVM_X86_OP_OPTIONAL(pi_update_irte)
+KVM_X86_OP_OPTIONAL(pi_start_assignment)
+KVM_X86_OP(apicv_post_state_restore)
+KVM_X86_OP_OPTIONAL(dy_apicv_has_pending_interrupt)
+KVM_X86_OP_OPTIONAL(set_hv_timer)
+KVM_X86_OP_OPTIONAL(cancel_hv_timer)
 KVM_X86_OP(setup_mce)
 KVM_X86_OP(smi_allowed)
 KVM_X86_OP(enter_smm)
 KVM_X86_OP(leave_smm)
 KVM_X86_OP(enable_smi_window)
-KVM_X86_OP_NULL(mem_enc_ioctl)
-KVM_X86_OP_NULL(mem_enc_register_region)
-KVM_X86_OP_NULL(mem_enc_unregister_region)
-KVM_X86_OP_NULL(vm_copy_enc_context_from)
-KVM_X86_OP_NULL(vm_move_enc_context_from)
+KVM_X86_OP_OPTIONAL(mem_enc_ioctl)
+KVM_X86_OP_OPTIONAL(mem_enc_register_region)
+KVM_X86_OP_OPTIONAL(mem_enc_unregister_region)
+KVM_X86_OP_OPTIONAL(vm_copy_enc_context_from)
+KVM_X86_OP_OPTIONAL(vm_move_enc_context_from)
 KVM_X86_OP(get_msr_feature)
 KVM_X86_OP(can_emulate_instruction)
 KVM_X86_OP(apic_init_signal_blocked)
-KVM_X86_OP_NULL(enable_direct_tlbflush)
-KVM_X86_OP_NULL(migrate_timers)
+KVM_X86_OP_OPTIONAL(enable_direct_tlbflush)
+KVM_X86_OP_OPTIONAL(migrate_timers)
 KVM_X86_OP(msr_filter_changed)
-KVM_X86_OP_NULL(complete_emulated_msr)
+KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
 
 #undef KVM_X86_OP
-#undef KVM_X86_OP_NULL
+#undef KVM_X86_OP_OPTIONAL

arch/x86/include/asm/kvm_host.h

@@ -1540,14 +1540,14 @@ extern struct kvm_x86_ops kvm_x86_ops;
 
 #define KVM_X86_OP(func) \
 	DECLARE_STATIC_CALL(kvm_x86_##func, *(((struct kvm_x86_ops *)0)->func));
-#define KVM_X86_OP_NULL KVM_X86_OP
+#define KVM_X86_OP_OPTIONAL KVM_X86_OP
 #include <asm/kvm-x86-ops.h>
 
 static inline void kvm_ops_static_call_update(void)
 {
 #define KVM_X86_OP(func) \
 	static_call_update(kvm_x86_##func, kvm_x86_ops.func);
-#define KVM_X86_OP_NULL KVM_X86_OP
+#define KVM_X86_OP_OPTIONAL KVM_X86_OP
 #include <asm/kvm-x86-ops.h>
 }
 

arch/x86/kvm/x86.c

@@ -130,7 +130,7 @@ struct kvm_x86_ops kvm_x86_ops __read_mostly;
 #define KVM_X86_OP(func)					     \
 	DEFINE_STATIC_CALL_NULL(kvm_x86_##func,			     \
 				*(((struct kvm_x86_ops *)0)->func));
-#define KVM_X86_OP_NULL KVM_X86_OP
+#define KVM_X86_OP_OPTIONAL KVM_X86_OP
 #include <asm/kvm-x86-ops.h>
 EXPORT_STATIC_CALL_GPL(kvm_x86_get_cs_db_l_bits);
 EXPORT_STATIC_CALL_GPL(kvm_x86_cache_reg);