From mboxrd@z Thu Jan 1 00:00:00 1970 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 7441CC4707A for ; Tue, 5 Apr 2022 10:08:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351498AbiDEKCf (ORCPT ); Tue, 5 Apr 2022 06:02:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237791AbiDEISV (ORCPT ); Tue, 5 Apr 2022 04:18:21 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96D0FB7140; Tue, 5 Apr 2022 01:07:31 -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 35B50B81BB0; Tue, 5 Apr 2022 08:07:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80E90C385A0; Tue, 5 Apr 2022 08:07:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649146049; bh=oSISaTF9nGf1NkBgZklJ3lIuiXPmyIAqJibQXdni6CA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lSMFYJJsw6k5bZfnMS/ZCupADuqUNBES1Lkhg4pmMABGHajCFSB815pn3ggFytlHK o1HlLiZgr/lRzBNk9Z9l1pYI6D1n5S9qqiyOSB9WBL4ard67XaGsD96QTujZbV+D+I qCBSPK0sYqvoUiGT7n9NXIWLqLOAthepujlI0iBw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Hou Wenlong , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.17 0623/1126] KVM: x86/emulator: Defer not-present segment check in __load_segment_descriptor() Date: Tue, 5 Apr 2022 09:22:50 +0200 Message-Id: <20220405070425.922671317@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hou Wenlong [ Upstream commit ca85f002258fdac3762c57d12d5e6e401b6a41af ] Per Intel's SDM on the "Instruction Set Reference", when loading segment descriptor, not-present segment check should be after all type and privilege checks. But the emulator checks it first, then #NP is triggered instead of #GP if privilege fails and segment is not present. Put not-present segment check after type and privilege checks in __load_segment_descriptor(). Fixes: 38ba30ba51a00 (KVM: x86 emulator: Emulate task switch in emulator.c) Reviewed-by: Sean Christopherson Signed-off-by: Hou Wenlong Message-Id: <52573c01d369f506cadcf7233812427cf7db81a7.1644292363.git.houwenlong.hwl@antgroup.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/emulate.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index e86d610dc6b7..02d061a06aa1 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1623,11 +1623,6 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, goto exception; } - if (!seg_desc.p) { - err_vec = (seg == VCPU_SREG_SS) ? SS_VECTOR : NP_VECTOR; - goto exception; - } - dpl = seg_desc.dpl; switch (seg) { @@ -1667,6 +1662,10 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, case VCPU_SREG_TR: if (seg_desc.s || (seg_desc.type != 1 && seg_desc.type != 9)) goto exception; + if (!seg_desc.p) { + err_vec = NP_VECTOR; + goto exception; + } old_desc = seg_desc; seg_desc.type |= 2; /* busy */ ret = ctxt->ops->cmpxchg_emulated(ctxt, desc_addr, &old_desc, &seg_desc, @@ -1691,6 +1690,11 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, break; } + if (!seg_desc.p) { + err_vec = (seg == VCPU_SREG_SS) ? SS_VECTOR : NP_VECTOR; + goto exception; + } + if (seg_desc.s) { /* mark segment as accessed */ if (!(seg_desc.type & 1)) { -- 2.34.1