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, 10 insertions, 18 deletions

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9c92b2993f5a..e71dc36850cb 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1516,7 +1516,7 @@ static int __skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	/* skipping an emulated instruction also counts */
 	vmx_set_interrupt_shadow(vcpu, 0);
 
-	return EMULATE_DONE;
+	return 1;
 }
 
 static inline void skip_emulated_instruction(struct kvm_vcpu *vcpu)
@@ -4468,7 +4468,7 @@ static int handle_rmode_exception(struct kvm_vcpu *vcpu,
 	 * Cause the #SS fault with 0 error code in VM86 mode.
 	 */
 	if (((vec == GP_VECTOR) || (vec == SS_VECTOR)) && err_code == 0) {
-		if (kvm_emulate_instruction(vcpu, 0) == EMULATE_DONE) {
+		if (kvm_emulate_instruction(vcpu, 0)) {
 			if (vcpu->arch.halt_request) {
 				vcpu->arch.halt_request = 0;
 				return kvm_vcpu_halt(vcpu);
@@ -4545,8 +4545,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 			kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
 			return 1;
 		}
-		return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
-							EMULATE_USER_EXIT;
+		return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP);
 	}
 
 	/*
@@ -4643,7 +4642,7 @@ static int handle_io(struct kvm_vcpu *vcpu)
 	++vcpu->stat.io_exits;
 
 	if (string)
-		return kvm_emulate_instruction(vcpu, 0) == EMULATE_DONE;
+		return kvm_emulate_instruction(vcpu, 0);
 
 	port = exit_qualification >> 16;
 	size = (exit_qualification & 7) + 1;
@@ -4717,7 +4716,7 @@ static int handle_set_cr4(struct kvm_vcpu *vcpu, unsigned long val)
 static int handle_desc(struct kvm_vcpu *vcpu)
 {
 	WARN_ON(!(vcpu->arch.cr4 & X86_CR4_UMIP));
-	return kvm_emulate_instruction(vcpu, 0) == EMULATE_DONE;
+	return kvm_emulate_instruction(vcpu, 0);
 }
 
 static int handle_cr(struct kvm_vcpu *vcpu)
@@ -4933,7 +4932,7 @@ static int handle_vmcall(struct kvm_vcpu *vcpu)
 
 static int handle_invd(struct kvm_vcpu *vcpu)
 {
-	return kvm_emulate_instruction(vcpu, 0) == EMULATE_DONE;
+	return kvm_emulate_instruction(vcpu, 0);
 }
 
 static int handle_invlpg(struct kvm_vcpu *vcpu)
@@ -5000,7 +4999,7 @@ static int handle_apic_access(struct kvm_vcpu *vcpu)
 			return kvm_skip_emulated_instruction(vcpu);
 		}
 	}
-	return kvm_emulate_instruction(vcpu, 0) == EMULATE_DONE;
+	return kvm_emulate_instruction(vcpu, 0);
 }
 
 static int handle_apic_eoi_induced(struct kvm_vcpu *vcpu)
@@ -5077,7 +5076,7 @@ static int handle_task_switch(struct kvm_vcpu *vcpu)
 	 */
 	return kvm_task_switch(vcpu, tss_selector,
 			       type == INTR_TYPE_SOFT_INTR ? idt_index : -1,
-			       reason, has_error_code, error_code) != EMULATE_USER_EXIT;
+			       reason, has_error_code, error_code);
 }
 
 static int handle_ept_violation(struct kvm_vcpu *vcpu)
@@ -5149,8 +5148,7 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
 		if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
 			return kvm_skip_emulated_instruction(vcpu);
 		else
-			return kvm_emulate_instruction(vcpu, EMULTYPE_SKIP) ==
-								EMULATE_DONE;
+			return kvm_emulate_instruction(vcpu, EMULTYPE_SKIP);
 	}
 
 	return kvm_mmu_page_fault(vcpu, gpa, PFERR_RSVD_MASK, NULL, 0);
@@ -5169,7 +5167,6 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu)
 static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	enum emulation_result err;
 	bool intr_window_requested;
 	unsigned count = 130;
 
@@ -5190,14 +5187,9 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
 		if (kvm_test_request(KVM_REQ_EVENT, vcpu))
 			return 1;
 
-		err = kvm_emulate_instruction(vcpu, 0);
-
-		if (err == EMULATE_USER_EXIT)
+		if (!kvm_emulate_instruction(vcpu, 0))
 			return 0;
 
-		if (WARN_ON_ONCE(err == EMULATE_FAIL))
-			return 1;
-
 		if (vmx->emulation_required && !vmx->rmode.vm86_active &&
 		    vcpu->arch.exception.pending) {
 			vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;