KVM: VMX: Fold ept_update_paging_mode_cr0() back into vmx_set_cr0()

Move the CR0/CR3/CR4 shenanigans for EPT without unrestricted guest back
into vmx_set_cr0().  This will allow a future patch to eliminate the
rather gross stuffing of vcpu->arch.cr0 in the paging transition cases
by snapshotting the old CR0.

No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-24-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -2994,27 +2994,6 @@ void ept_save_pdptrs(struct kvm_vcpu *vcpu)
 	kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
 }
 
-static void ept_update_paging_mode_cr0(unsigned long cr0, struct kvm_vcpu *vcpu)
-{
-	struct vcpu_vmx *vmx = to_vmx(vcpu);
-
-	if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))
-		vmx_cache_reg(vcpu, VCPU_EXREG_CR3);
-	if (!(cr0 & X86_CR0_PG)) {
-		/* From paging/starting to nonpaging */
-		exec_controls_setbit(vmx, CPU_BASED_CR3_LOAD_EXITING |
-					  CPU_BASED_CR3_STORE_EXITING);
-		vcpu->arch.cr0 = cr0;
-		vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
-	} else if (!is_paging(vcpu)) {
-		/* From nonpaging to paging */
-		exec_controls_clearbit(vmx, CPU_BASED_CR3_LOAD_EXITING |
-					    CPU_BASED_CR3_STORE_EXITING);
-		vcpu->arch.cr0 = cr0;
-		vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
-	}
-}
-
 void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -3044,8 +3023,23 @@ void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 	}
 #endif
 
-	if (enable_ept && !is_unrestricted_guest(vcpu))
-		ept_update_paging_mode_cr0(cr0, vcpu);
+	if (enable_ept && !is_unrestricted_guest(vcpu)) {
+		if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))
+			vmx_cache_reg(vcpu, VCPU_EXREG_CR3);
+		if (!(cr0 & X86_CR0_PG)) {
+			/* From paging/starting to nonpaging */
+			exec_controls_setbit(vmx, CPU_BASED_CR3_LOAD_EXITING |
+						  CPU_BASED_CR3_STORE_EXITING);
+			vcpu->arch.cr0 = cr0;
+			vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
+		} else if (!is_paging(vcpu)) {
+			/* From nonpaging to paging */
+			exec_controls_clearbit(vmx, CPU_BASED_CR3_LOAD_EXITING |
+						    CPU_BASED_CR3_STORE_EXITING);
+			vcpu->arch.cr0 = cr0;
+			vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
+		}
+	}
 
 	vmcs_writel(CR0_READ_SHADOW, cr0);
 	vmcs_writel(GUEST_CR0, hw_cr0);