KVM: x86: Remove emulation_result enums, EMULATE_{DONE,FAIL,USER_EXIT}

Deferring emulation failure handling (in some cases) to the caller of
x86_emulate_instruction() has proven fragile, e.g. multiple instances of
KVM not setting run->exit_reason on EMULATE_FAIL, largely due to it
being difficult to discern what emulation types can return what result,
and which combination of types and results are handled where.

Now that x86_emulate_instruction() always handles emulation failure,
i.e. EMULATION_FAIL is only referenced in callers, remove the
emulation_result enums entirely.  Per KVM's existing exit handling
conventions, return '0' and '1' for "exit to userspace" and "resume
guest" respectively.  Doing so cleans up many callers, e.g. they can
return kvm_emulate_instruction() directly instead of having to interpret
its result.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 28 insertions, 29 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 92b6690d0512..a83b269126a0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5451,7 +5451,7 @@ int handle_ud(struct kvm_vcpu *vcpu)
 		emul_type = EMULTYPE_TRAP_UD_FORCED;
 	}
 
-	return kvm_emulate_instruction(vcpu, emul_type) != EMULATE_USER_EXIT;
+	return kvm_emulate_instruction(vcpu, emul_type);
 }
 EXPORT_SYMBOL_GPL(handle_ud);
 
@@ -6302,14 +6302,14 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
 
 	if (emulation_type & EMULTYPE_VMWARE_GP) {
 		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-		return EMULATE_DONE;
+		return 1;
 	}
 
 	if (emulation_type & EMULTYPE_SKIP) {
 		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
 		vcpu->run->internal.ndata = 0;
-		return EMULATE_USER_EXIT;
+		return 0;
 	}
 
 	kvm_queue_exception(vcpu, UD_VECTOR);
@@ -6318,10 +6318,10 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
 		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
 		vcpu->run->internal.ndata = 0;
-		return EMULATE_USER_EXIT;
+		return 0;
 	}
 
-	return EMULATE_DONE;
+	return 1;
 }
 
 static bool reexecute_instruction(struct kvm_vcpu *vcpu, gva_t cr2,
@@ -6485,10 +6485,10 @@ static int kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu)
 		kvm_run->debug.arch.pc = vcpu->arch.singlestep_rip;
 		kvm_run->debug.arch.exception = DB_VECTOR;
 		kvm_run->exit_reason = KVM_EXIT_DEBUG;
-		return EMULATE_USER_EXIT;
+		return 0;
 	}
 	kvm_queue_exception_p(vcpu, DB_VECTOR, DR6_BS);
-	return EMULATE_DONE;
+	return 1;
 }
 
 int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
@@ -6497,7 +6497,7 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	int r;
 
 	r = kvm_x86_ops->skip_emulated_instruction(vcpu);
-	if (unlikely(r != EMULATE_DONE))
+	if (unlikely(!r))
 		return 0;
 
 	/*
@@ -6510,7 +6510,7 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	 */
 	if (unlikely(rflags & X86_EFLAGS_TF))
 		r = kvm_vcpu_do_singlestep(vcpu);
-	return r == EMULATE_DONE;
+	return r;
 }
 EXPORT_SYMBOL_GPL(kvm_skip_emulated_instruction);
 
@@ -6529,7 +6529,7 @@ static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r)
 			kvm_run->debug.arch.pc = eip;
 			kvm_run->debug.arch.exception = DB_VECTOR;
 			kvm_run->exit_reason = KVM_EXIT_DEBUG;
-			*r = EMULATE_USER_EXIT;
+			*r = 0;
 			return true;
 		}
 	}
@@ -6545,7 +6545,7 @@ static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r)
 			vcpu->arch.dr6 &= ~DR_TRAP_BITS;
 			vcpu->arch.dr6 |= dr6 | DR6_RTM;
 			kvm_queue_exception(vcpu, DB_VECTOR);
-			*r = EMULATE_DONE;
+			*r = 1;
 			return true;
 		}
 	}
@@ -6632,11 +6632,11 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 			if ((emulation_type & EMULTYPE_TRAP_UD) ||
 			    (emulation_type & EMULTYPE_TRAP_UD_FORCED)) {
 				kvm_queue_exception(vcpu, UD_VECTOR);
-				return EMULATE_DONE;
+				return 1;
 			}
 			if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
 						emulation_type))
-				return EMULATE_DONE;
+				return 1;
 			if (ctxt->have_exception) {
 				/*
 				 * #UD should result in just EMULATION_FAILED, and trap-like
@@ -6645,7 +6645,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 				WARN_ON_ONCE(ctxt->exception.vector == UD_VECTOR ||
 					     exception_type(ctxt->exception.vector) == EXCPT_TRAP);
 				inject_emulated_exception(vcpu);
-				return EMULATE_DONE;
+				return 1;
 			}
 			return handle_emulation_failure(vcpu, emulation_type);
 		}
@@ -6654,7 +6654,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 	if ((emulation_type & EMULTYPE_VMWARE_GP) &&
 	    !is_vmware_backdoor_opcode(ctxt)) {
 		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-		return EMULATE_DONE;
+		return 1;
 	}
 
 	if (emulation_type & EMULTYPE_SKIP) {
@@ -6662,11 +6662,11 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 		if (ctxt->eflags & X86_EFLAGS_RF)
 			kvm_set_rflags(vcpu, ctxt->eflags & ~X86_EFLAGS_RF);
 		kvm_x86_ops->set_interrupt_shadow(vcpu, 0);
-		return EMULATE_DONE;
+		return 1;
 	}
 
 	if (retry_instruction(ctxt, cr2, emulation_type))
-		return EMULATE_DONE;
+		return 1;
 
 	/* this is needed for vmware backdoor interface to work since it
 	   changes registers values  during IO operation */
@@ -6682,18 +6682,18 @@ restart:
 	r = x86_emulate_insn(ctxt);
 
 	if (r == EMULATION_INTERCEPTED)
-		return EMULATE_DONE;
+		return 1;
 
 	if (r == EMULATION_FAILED) {
 		if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
 					emulation_type))
-			return EMULATE_DONE;
+			return 1;
 
 		return handle_emulation_failure(vcpu, emulation_type);
 	}
 
 	if (ctxt->have_exception) {
-		r = EMULATE_DONE;
+		r = 1;
 		if (inject_emulated_exception(vcpu))
 			return r;
 	} else if (vcpu->arch.pio.count) {
@@ -6704,18 +6704,18 @@ restart:
 			writeback = false;
 			vcpu->arch.complete_userspace_io = complete_emulated_pio;
 		}
-		r = EMULATE_USER_EXIT;
+		r = 0;
 	} else if (vcpu->mmio_needed) {
 		++vcpu->stat.mmio_exits;
 
 		if (!vcpu->mmio_is_write)
 			writeback = false;
-		r = EMULATE_USER_EXIT;
+		r = 0;
 		vcpu->arch.complete_userspace_io = complete_emulated_mmio;
 	} else if (r == EMULATION_RESTART)
 		goto restart;
 	else
-		r = EMULATE_DONE;
+		r = 1;
 
 	if (writeback) {
 		unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);
@@ -6724,7 +6724,7 @@ restart:
 		if (!ctxt->have_exception ||
 		    exception_type(ctxt->exception.vector) == EXCPT_TRAP) {
 			kvm_rip_write(vcpu, ctxt->eip);
-			if (r == EMULATE_DONE && ctxt->tf)
+			if (r && ctxt->tf)
 				r = kvm_vcpu_do_singlestep(vcpu);
 			__kvm_set_rflags(vcpu, ctxt->eflags);
 		}
@@ -8319,12 +8319,11 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
 static inline int complete_emulated_io(struct kvm_vcpu *vcpu)
 {
 	int r;
+
 	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 	r = kvm_emulate_instruction(vcpu, EMULTYPE_NO_DECODE);
 	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
-	if (r != EMULATE_DONE)
-		return 0;
-	return 1;
+	return r;
 }
 
 static int complete_emulated_pio(struct kvm_vcpu *vcpu)
@@ -8696,13 +8695,13 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
 		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
 		vcpu->run->internal.ndata = 0;
-		return EMULATE_USER_EXIT;
+		return 0;
 	}
 
 	kvm_rip_write(vcpu, ctxt->eip);
 	kvm_set_rflags(vcpu, ctxt->eflags);
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
-	return EMULATE_DONE;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(kvm_task_switch);