KVM: x86: cleanup kvm_inject_emulated_page_fault

To reconstruct the kvm_mmu to be used for page fault injection, we
can simply use fault->nested_page_fault.  This matches how
fault->nested_page_fault is assigned in the first place by
FNAME(walk_addr_generic).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -4353,12 +4353,6 @@ static unsigned long get_cr3(struct kvm_vcpu *vcpu)
 	return kvm_read_cr3(vcpu);
 }
 
-static void inject_page_fault(struct kvm_vcpu *vcpu,
-			      struct x86_exception *fault)
-{
-	vcpu->arch.mmu->inject_page_fault(vcpu, fault);
-}
-
 static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn,
 			   unsigned int access, int *nr_present)
 {

arch/x86/kvm/mmu/paging_tmpl.h

@@ -812,7 +812,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,
 	if (!r) {
 		pgprintk("%s: guest page fault\n", __func__);
 		if (!prefault)
-			inject_page_fault(vcpu, &walker.fault);
+			kvm_inject_emulated_page_fault(vcpu, &walker.fault);
 
 		return RET_PF_RETRY;
 	}

arch/x86/kvm/x86.c

@@ -614,12 +614,12 @@ EXPORT_SYMBOL_GPL(kvm_inject_page_fault);
 bool kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
 				    struct x86_exception *fault)
 {
+	struct kvm_mmu *fault_mmu;
 	WARN_ON_ONCE(fault->vector != PF_VECTOR);
 
-	if (mmu_is_nested(vcpu) && !fault->nested_page_fault)
-		vcpu->arch.nested_mmu.inject_page_fault(vcpu, fault);
-	else
-		vcpu->arch.mmu->inject_page_fault(vcpu, fault);
+	fault_mmu = fault->nested_page_fault ? vcpu->arch.mmu :
+					       vcpu->arch.walk_mmu;
+	fault_mmu->inject_page_fault(vcpu, fault);
 
 	return fault->nested_page_fault;
 }