KVM: x86: Move #GP injection for VMware into x86_emulate_instruction()

Immediately inject a #GP when VMware emulation fails and return
EMULATE_DONE instead of propagating EMULATE_FAIL up the stack.  This
helps pave the way for removing EMULATE_FAIL altogether.

Rename EMULTYPE_VMWARE to EMULTYPE_VMWARE_GP to document that the x86
emulator is called to handle VMware #GP interception, e.g. why a #GP
is injected on emulation failure for EMULTYPE_VMWARE_GP.

Drop EMULTYPE_NO_UD_ON_FAIL as a standalone type.  The "no #UD on fail"
is used only in the VMWare case and is obsoleted by having the emulator
itself reinject #GP.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1325,8 +1325,7 @@ enum emulation_result {
 #define EMULTYPE_TRAP_UD	    (1 << 1)
 #define EMULTYPE_SKIP		    (1 << 2)
 #define EMULTYPE_ALLOW_RETRY	    (1 << 3)
-#define EMULTYPE_NO_UD_ON_FAIL	    (1 << 4)
-#define EMULTYPE_VMWARE		    (1 << 5)
+#define EMULTYPE_VMWARE_GP	    (1 << 5)
 int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
 int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
 					void *insn, int insn_len);

arch/x86/kvm/svm.c

@@ -2768,7 +2768,6 @@ static int gp_interception(struct vcpu_svm *svm)
 {
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 	u32 error_code = svm->vmcb->control.exit_info_1;
-	int er;
 
 	WARN_ON_ONCE(!enable_vmware_backdoor);
 
@@ -2780,13 +2779,8 @@ static int gp_interception(struct vcpu_svm *svm)
 		kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
 		return 1;
 	}
-	er = kvm_emulate_instruction(vcpu,
-		EMULTYPE_VMWARE | EMULTYPE_NO_UD_ON_FAIL);
-	if (er == EMULATE_USER_EXIT)
-		return 0;
-	else if (er != EMULATE_DONE)
-		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-	return 1;
+	return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
+						EMULATE_USER_EXIT;
 }
 
 static bool is_erratum_383(void)

arch/x86/kvm/vmx/vmx.c

@@ -4522,7 +4522,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 	u32 intr_info, ex_no, error_code;
 	unsigned long cr2, rip, dr6;
 	u32 vect_info;
-	enum emulation_result er;
 
 	vect_info = vmx->idt_vectoring_info;
 	intr_info = vmx->exit_intr_info;
@@ -4549,13 +4548,8 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 			kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
 			return 1;
 		}
-		er = kvm_emulate_instruction(vcpu,
-			EMULTYPE_VMWARE | EMULTYPE_NO_UD_ON_FAIL);
-		if (er == EMULATE_USER_EXIT)
-			return 0;
-		else if (er != EMULATE_DONE)
-			kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-		return 1;
+		return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
+							EMULATE_USER_EXIT;
 	}
 
 	/*

arch/x86/kvm/x86.c

@@ -6307,8 +6307,10 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
 	++vcpu->stat.insn_emulation_fail;
 	trace_kvm_emulate_insn_failed(vcpu);
 
-	if (emulation_type & EMULTYPE_NO_UD_ON_FAIL)
-		return EMULATE_FAIL;
+	if (emulation_type & EMULTYPE_VMWARE_GP) {
+		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+		return EMULATE_DONE;
+	}
 
 	kvm_queue_exception(vcpu, UD_VECTOR);
 
@@ -6648,9 +6650,11 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 		}
 	}
 
-	if ((emulation_type & EMULTYPE_VMWARE) &&
-	    !is_vmware_backdoor_opcode(ctxt))
-		return EMULATE_FAIL;
+	if ((emulation_type & EMULTYPE_VMWARE_GP) &&
+	    !is_vmware_backdoor_opcode(ctxt)) {
+		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+		return EMULATE_DONE;
+	}
 
 	if (emulation_type & EMULTYPE_SKIP) {
 		kvm_rip_write(vcpu, ctxt->_eip);