KVM: VMX: Always signal #GP on WRMSR to MSR_IA32_CR_PAT with bad value

[ Upstream commit d28f4290 ]

The behavior of WRMSR is in no way dependent on whether or not KVM
consumes the value.

Fixes: 4566654b ("KVM: vmx: Inject #GP on invalid PAT CR")
Cc: stable@vger.kernel.org
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/x86/kvm/vmx.c

@@ -4265,9 +4265,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 					      MSR_TYPE_W);
 		break;
 	case MSR_IA32_CR_PAT:
-		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
 		if (!kvm_pat_valid(data))
 			return 1;
+
+		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
 			vmcs_write64(GUEST_IA32_PAT, data);
 			vcpu->arch.pat = data;
 			break;