KVM: nVMX: Move guest non-reg state checks to VM-Exit path

Per Intel's SDM, volume 3, section Checking and Loading Guest State:

  Because the checking and the loading occur concurrently, a failure may
  be discovered only after some state has been loaded. For this reason,
  the logical processor responds to such failures by loading state from
  the host-state area, as it would for a VM exit.

In other words, a failed non-register state consistency check results in
a VM-Exit, not VM-Fail.  Moving the non-reg state checks also paves the
way for renaming nested_vmx_check_vmentry_postreqs() to align with the
SDM, i.e. nested_vmx_check_vmentry_guest_state().

Fixes: 26539bd0 ("KVM: nVMX: check vmcs12 for valid activity state")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/nested.c

@@ -2628,18 +2628,6 @@ static int nested_check_host_control_regs(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
-/*
- * Checks related to Guest Non-register State
- */
-static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
-{
-	if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
-	    vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT)
-		return -EINVAL;
-
-	return 0;
-}
-
 static int nested_vmx_check_vmentry_prereqs(struct kvm_vcpu *vcpu,
 					    struct vmcs12 *vmcs12)
 {
@@ -2651,9 +2639,6 @@ static int nested_vmx_check_vmentry_prereqs(struct kvm_vcpu *vcpu,
 	if (nested_check_host_control_regs(vcpu, vmcs12))
 		return VMXERR_ENTRY_INVALID_HOST_STATE_FIELD;
 
-	if (nested_check_guest_non_reg_state(vmcs12))
-		return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
-
 	return 0;
 }
 
@@ -2684,6 +2669,18 @@ static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
 	return r;
 }
 
+/*
+ * Checks related to Guest Non-register State
+ */
+static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
+{
+	if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
+	    vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int nested_vmx_check_vmentry_postreqs(struct kvm_vcpu *vcpu,
 					     struct vmcs12 *vmcs12,
 					     u32 *exit_qual)
@@ -2729,6 +2726,9 @@ static int nested_vmx_check_vmentry_postreqs(struct kvm_vcpu *vcpu,
 		(vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))
 			return 1;
 
+	if (nested_check_guest_non_reg_state(vmcs12))
+		return 1;
+
 	return 0;
 }