KVM: nSVM: prepare to handle errors from enter_svm_guest_mode()

Some operations in enter_svm_guest_mode() may fail, e.g. currently
we suppress kvm_set_cr3() return value. Prepare the code to proparate
errors.

No functional change intended.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-5-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/nested.c

@@ -404,7 +404,7 @@ static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
 	vmcb_mark_all_dirty(svm->vmcb);
 }
 
-void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
+int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 			  struct vmcb *nested_vmcb)
 {
 	svm->nested.vmcb = vmcb_gpa;
@@ -413,6 +413,8 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 	nested_prepare_vmcb_control(svm);
 
 	svm_set_gif(svm, true);
+
+	return 0;
 }
 
 int nested_svm_vmrun(struct vcpu_svm *svm)
@@ -490,18 +492,22 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
 	copy_vmcb_control_area(&hsave->control, &vmcb->control);
 
 	svm->nested.nested_run_pending = 1;
-	enter_svm_guest_mode(svm, vmcb_gpa, nested_vmcb);
 
-	if (!nested_svm_vmrun_msrpm(svm)) {
-		svm->nested.nested_run_pending = 0;
+	if (enter_svm_guest_mode(svm, vmcb_gpa, nested_vmcb))
+		goto out_exit_err;
 
-		svm->vmcb->control.exit_code    = SVM_EXIT_ERR;
-		svm->vmcb->control.exit_code_hi = 0;
-		svm->vmcb->control.exit_info_1  = 0;
-		svm->vmcb->control.exit_info_2  = 0;
+	if (nested_svm_vmrun_msrpm(svm))
+		goto out;
 
-		nested_svm_vmexit(svm);
-	}
+out_exit_err:
+	svm->nested.nested_run_pending = 0;
+
+	svm->vmcb->control.exit_code    = SVM_EXIT_ERR;
+	svm->vmcb->control.exit_code_hi = 0;
+	svm->vmcb->control.exit_info_1  = 0;
+	svm->vmcb->control.exit_info_2  = 0;
+
+	nested_svm_vmexit(svm);
 
 out:
 	kvm_vcpu_unmap(&svm->vcpu, &map, true);

arch/x86/kvm/svm/svm.c

@@ -3889,6 +3889,7 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 	struct kvm_host_map map;
 	u64 guest;
 	u64 vmcb;
+	int ret = 0;
 
 	guest = GET_SMSTATE(u64, smstate, 0x7ed8);
 	vmcb = GET_SMSTATE(u64, smstate, 0x7ee0);
@@ -3897,10 +3898,11 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 		if (kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb), &map) == -EINVAL)
 			return 1;
 		nested_vmcb = map.hva;
-		enter_svm_guest_mode(svm, vmcb, nested_vmcb);
+		ret = enter_svm_guest_mode(svm, vmcb, nested_vmcb);
 		kvm_vcpu_unmap(&svm->vcpu, &map, true);
 	}
-	return 0;
+
+	return ret;
 }
 
 static void enable_smi_window(struct kvm_vcpu *vcpu)

arch/x86/kvm/svm/svm.h

@@ -387,8 +387,8 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm)
 	return (svm->nested.ctl.intercept & (1ULL << INTERCEPT_NMI));
 }
 
-void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
-			  struct vmcb *nested_vmcb);
+int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
+			 struct vmcb *nested_vmcb);
 void svm_leave_nested(struct vcpu_svm *svm);
 int nested_svm_vmrun(struct vcpu_svm *svm);
 void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb);