[PATCH v3 5/9] KVM: nSVM: introduce nested_svm_load_cr3()

[Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>]

As a preparatory change for implementing nested specifig PGD switch for
nSVM (following nVMX' nested_vmx_load_cr3()) instead of relying on
kvm_set_cr3() introduce nested_svm_load_cr3().

The only intended functional change for now is that errors from
kvm_set_cr3() are propagated.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
 arch/x86/kvm/svm/nested.c | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 5e6c988a4e6b..d0fd63e8d835 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -311,8 +311,25 @@ static void nested_vmcb_save_pending_event(struct vcpu_svm *svm,
 	nested_vmcb->control.exit_int_info = exit_int_info;
 }
 
-static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
+static inline bool nested_npt_enabled(struct vcpu_svm *svm)
 {
+	return svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE;
+}
+
+/*
+ * Load guest's cr3 at nested entry. @nested_npt is true if we are
+ * emulating VM-Entry into a guest with NPT enabled.
+ */
+static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
+			       bool nested_npt)
+{
+	return kvm_set_cr3(vcpu, cr3);
+}
+
+static int nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
+{
+	int ret = 0;
+
 	/* Load the nested guest state */
 	svm->vmcb->save.es = nested_vmcb->save.es;
 	svm->vmcb->save.cs = nested_vmcb->save.cs;
@@ -324,7 +341,9 @@ static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_v
 	svm_set_efer(&svm->vcpu, nested_vmcb->save.efer);
 	svm_set_cr0(&svm->vcpu, nested_vmcb->save.cr0);
 	svm_set_cr4(&svm->vcpu, nested_vmcb->save.cr4);
-	(void)kvm_set_cr3(&svm->vcpu, nested_vmcb->save.cr3);
+
+	ret = nested_svm_load_cr3(&svm->vcpu, nested_vmcb->save.cr3,
+				  nested_npt_enabled(svm));
 
 	svm->vmcb->save.cr2 = svm->vcpu.arch.cr2 = nested_vmcb->save.cr2;
 	kvm_rax_write(&svm->vcpu, nested_vmcb->save.rax);
@@ -338,12 +357,14 @@ static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_v
 	svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
 	svm->vcpu.arch.dr6  = nested_vmcb->save.dr6;
 	svm->vmcb->save.cpl = nested_vmcb->save.cpl;
+
+	return ret;
 }
 
 static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
 {
 	const u32 mask = V_INTR_MASKING_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK;
-	if (svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE)
+	if (nested_npt_enabled(svm))
 		nested_svm_init_mmu_context(&svm->vcpu);
 
 	/* Guest paging mode is active - reset mmu */
@@ -382,9 +403,15 @@ static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
 int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 			  struct vmcb *nested_vmcb)
 {
+	int ret;
+
 	svm->nested.vmcb = vmcb_gpa;
 	load_nested_vmcb_control(svm, &nested_vmcb->control);
-	nested_prepare_vmcb_save(svm, nested_vmcb);
+
+	ret = nested_prepare_vmcb_save(svm, nested_vmcb);
+	if (ret)
+		return ret;
+
 	nested_prepare_vmcb_control(svm);
 
 	svm_set_gif(svm, true);
-- 
2.25.4