[PATCH v4 3/3] KVM: nVMX: Enable nested msr load/restore feature

[Eugene Korenevsky <ekorenevsky@gmail.com>]

On nested entry:
 - check msr switch area.
 - load L2's MSRs. If failed, terminate nested entry
   and load L1's state. If failed on loading L1's MSRs
   again, do nested vmx abort.

On nested exit:
 - restore L2's MSRs. If failed, do nested vmx abort.
 - load L1's MSRs. If failed, do nested vmx abort.

Signed-off-by: Wincy Van <fanwenyi0529@gmail.com>
Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
---
 arch/x86/kvm/vmx.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ac1fa1c2..ddb28e2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8745,6 +8745,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	int cpu;
 	struct loaded_vmcs *vmcs02;
 	bool ia32e;
+	u32 msr_entry_idx;
 
 	if (!nested_vmx_check_permission(vcpu) ||
 	    !nested_vmx_check_vmcs12(vcpu))
@@ -8792,11 +8793,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 		return 1;
 	}
 
-	if (vmcs12->vm_entry_msr_load_count > 0 ||
-	    vmcs12->vm_exit_msr_load_count > 0 ||
-	    vmcs12->vm_exit_msr_store_count > 0) {
-		pr_warn_ratelimited("%s: VMCS MSR_{LOAD,STORE} unsupported\n",
-				    __func__);
+	if (nested_vmx_check_msr_switch_controls(vcpu, vmcs12)) {
 		nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
 		return 1;
 	}
@@ -8902,10 +8899,21 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 
 	vmx_segment_cache_clear(vmx);
 
-	vmcs12->launch_state = 1;
-
 	prepare_vmcs02(vcpu, vmcs12);
 
+	msr_entry_idx = nested_vmx_load_msr(vcpu,
+					    vmcs12->vm_entry_msr_load_addr,
+					    vmcs12->vm_entry_msr_load_count);
+	if (msr_entry_idx) {
+		leave_guest_mode(vcpu);
+		vmx_load_vmcs01(vcpu);
+		nested_vmx_entry_failure(vcpu, vmcs12,
+				EXIT_REASON_MSR_LOAD_FAIL, msr_entry_idx);
+		return 1;
+	}
+
+	vmcs12->launch_state = 1;
+
 	if (vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT)
 		return kvm_emulate_halt(vcpu);
 
@@ -9335,6 +9343,10 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
 
 	kvm_set_dr(vcpu, 7, 0x400);
 	vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
+
+	if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr,
+				vmcs12->vm_exit_msr_load_count))
+		nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_MSR_FAIL);
 }
 
 /*
@@ -9356,6 +9368,10 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info,
 		       exit_qualification);
 
+	if (nested_vmx_store_msr(vcpu, vmcs12->vm_exit_msr_store_addr,
+				 vmcs12->vm_exit_msr_store_count))
+		nested_vmx_abort(vcpu, VMX_ABORT_SAVE_GUEST_MSR_FAIL);
+
 	vmx_load_vmcs01(vcpu);
 
 	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
-- 
2.0.4