From nobody Mon Sep 29 21:09:03 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3E2EC25B0E for ; Mon, 15 Aug 2022 21:53:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344835AbiHOVxg (ORCPT ); Mon, 15 Aug 2022 17:53:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350285AbiHOVu6 (ORCPT ); Mon, 15 Aug 2022 17:50:58 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74D83DEB7D; Mon, 15 Aug 2022 12:32:25 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 967A6B80FD3; Mon, 15 Aug 2022 19:32:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3291C433D6; Mon, 15 Aug 2022 19:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660591942; bh=RIXvlqtErnqUU+6Rz5r6bqonG4MImcLLPCMCxhVxYak=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gVudz0XcvtFdoKs2UH7LtgyjxoH0EgXd3/6idn3t+GtQ54+yrdBrrweaeppHs6fst MbrRMn67yowA0kzbt8n09eb9qkGrmGxzW4WF2yReN4H/jMQbYsnKFTPdmtGODTr1RH I4LHmlGa2qEUEgU+qtwMipmLLleBM/HEv68/3YQc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.19 0034/1157] KVM: nVMX: Account for KVM reserved CR4 bits in consistency checks Date: Mon, 15 Aug 2022 19:49:50 +0200 Message-Id: <20220815180440.799547938@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180439.416659447@linuxfoundation.org> References: <20220815180439.416659447@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Sean Christopherson commit ca58f3aa53d165afe4ab74c755bc2f6d168617ac upstream. Check that the guest (L2) and host (L1) CR4 values that would be loaded by nested VM-Enter and VM-Exit respectively are valid with respect to KVM's (L0 host) allowed CR4 bits. Failure to check KVM reserved bits would allow L1 to load an illegal CR4 (or trigger hardware VM-Fail or failed VM-Entry) by massaging guest CPUID to allow features that are not supported by KVM. Amusingly, KVM itself is an accomplice in its doom, as KVM adjusts L1's MSR_IA32_VMX_CR4_FIXED1 to allow L1 to enable bits for L2 based on L1's CPUID model. Note, although nested_{guest,host}_cr4_valid() are _currently_ used if and only if the vCPU is post-VMXON (nested.vmxon =3D=3D true), that may not be true in the future, e.g. emulating VMXON has a bug where it doesn't check the allowed/required CR0/CR4 bits. Cc: stable@vger.kernel.org Fixes: 3899152ccbf4 ("KVM: nVMX: fix checks on CR{0,4} during virtual VMX o= peration") Signed-off-by: Sean Christopherson Message-Id: <20220607213604.3346000-3-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx/nested.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/vmx/nested.h +++ b/arch/x86/kvm/vmx/nested.h @@ -281,7 +281,8 @@ static inline bool nested_cr4_valid(stru u64 fixed0 =3D to_vmx(vcpu)->nested.msrs.cr4_fixed0; u64 fixed1 =3D to_vmx(vcpu)->nested.msrs.cr4_fixed1; =20 - return fixed_bits_valid(val, fixed0, fixed1); + return fixed_bits_valid(val, fixed0, fixed1) && + __kvm_is_valid_cr4(vcpu, val); } =20 /* No difference in the restrictions on guest and host CR4 in VMX operatio= n. */