From patchwork Tue Feb 8 09:34:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Wenlong X-Patchwork-Id: 12738408 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 1577EC433EF for ; Tue, 8 Feb 2022 09:34:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355404AbiBHJeS (ORCPT ); Tue, 8 Feb 2022 04:34:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355385AbiBHJeP (ORCPT ); Tue, 8 Feb 2022 04:34:15 -0500 Received: from out0-148.mail.aliyun.com (out0-148.mail.aliyun.com [140.205.0.148]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D9C1C03FEC1; Tue, 8 Feb 2022 01:34:14 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018047199;MF=houwenlong.hwl@antgroup.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---.Mn.uQL0_1644312849; Received: from localhost(mailfrom:houwenlong.hwl@antgroup.com fp:SMTPD_---.Mn.uQL0_1644312849) by smtp.aliyun-inc.com(127.0.0.1); Tue, 08 Feb 2022 17:34:09 +0800 From: "Hou Wenlong" To: kvm@vger.kernel.org Cc: Sean Christopherson , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] KVM: x86/emulator: Move the unhandled outer privilege level logic of far return into __load_segment_descriptor() Date: Tue, 08 Feb 2022 17:34:05 +0800 Message-Id: <5b7188e6388ac9f4567d14eab32db9adf3e00119.1644292363.git.houwenlong.hwl@antgroup.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Outer-privilege level return is not implemented in emulator, move the unhandled logic into __load_segment_descriptor to make it easier to understand why the checks for RET are incomplete. Suggested-by: Sean Christopherson Signed-off-by: Hou Wenlong --- arch/x86/kvm/emulate.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 37c4213bdcc1..bd91b952eb0a 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1631,9 +1631,14 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, if (!(seg_desc.type & 8)) goto exception; - /* RET can never return to an inner privilege level. */ - if (transfer == X86_TRANSFER_RET && rpl < cpl) - goto exception; + if (transfer == X86_TRANSFER_RET) { + /* RET can never return to an inner privilege level. */ + if (rpl < cpl) + goto exception; + /* Outer-privilege level return is not implemented */ + if (rpl > cpl) + return X86EMUL_UNHANDLEABLE; + } if (transfer == X86_TRANSFER_RET || transfer == X86_TRANSFER_TASK_SWITCH) { if (seg_desc.type & 4) { /* conforming */ @@ -2228,9 +2233,6 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) rc = emulate_pop(ctxt, &cs, ctxt->op_bytes); if (rc != X86EMUL_CONTINUE) return rc; - /* Outer-privilege level return is not implemented */ - if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl) - return X86EMUL_UNHANDLEABLE; rc = __load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS, cpl, X86_TRANSFER_RET, &new_desc);