KVM: nVMX: check vmcs12 for valid activity state

KVM does not use the activity state VMCS field, and does not support
it in nested VMX either (the corresponding bits in the misc VMX feature
MSR are zero).  Fail entry if the activity state is set to anything but
"active".

Since the value will always be the same for L1 and L2, we do not need
to read and write the corresponding VMCS field on L1/L2 transitions,
either.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/vmx.c

@@ -7106,7 +7106,6 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 		vmcs12->vm_entry_instruction_len);
 	vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
 		vmcs12->guest_interruptibility_info);
-	vmcs_write32(GUEST_ACTIVITY_STATE, vmcs12->guest_activity_state);
 	vmcs_write32(GUEST_SYSENTER_CS, vmcs12->guest_sysenter_cs);
 	kvm_set_dr(vcpu, 7, vmcs12->guest_dr7);
 	vmcs_writel(GUEST_RFLAGS, vmcs12->guest_rflags);
@@ -7325,6 +7324,11 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 		return 1;
 	}
 
+	if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE) {
+		nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
+		return 1;
+	}
+
 	if ((vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_MSR_BITMAPS) &&
 			!IS_ALIGNED(vmcs12->msr_bitmap, PAGE_SIZE)) {
 		/*TODO: Also verify bits beyond physical address width are 0*/
@@ -7555,7 +7559,6 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	vmcs12->guest_gdtr_base = vmcs_readl(GUEST_GDTR_BASE);
 	vmcs12->guest_idtr_base = vmcs_readl(GUEST_IDTR_BASE);
 
-	vmcs12->guest_activity_state = vmcs_read32(GUEST_ACTIVITY_STATE);
 	vmcs12->guest_interruptibility_info =
 		vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
 	vmcs12->guest_pending_dbg_exceptions =