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, 2 insertions, 12 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 138dcdef8a06..84e1a9c661dd 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5383,7 +5383,6 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,
 		       void *insn, int insn_len)
 {
 	int r, emulation_type = 0;
-	enum emulation_result er;
 	bool direct = vcpu->arch.mmu->direct_map;
 
 	/* With shadow page tables, fault_address contains a GVA or nGPA.  */
@@ -5450,17 +5449,8 @@ emulate:
 			return 1;
 	}
 
-	er = x86_emulate_instruction(vcpu, cr2, emulation_type, insn, insn_len);
-
-	switch (er) {
-	case EMULATE_DONE:
-		return 1;
-	case EMULATE_USER_EXIT:
-	case EMULATE_FAIL:
-		return 0;
-	default:
-		BUG();
-	}
+	return x86_emulate_instruction(vcpu, cr2, emulation_type, insn,
+				       insn_len);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);