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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 477ABC43331 for ; Tue, 31 Mar 2020 15:58:43 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2154D20784 for ; Tue, 31 Mar 2020 15:58:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2154D20784 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jJJHU-0007M7-Rv; Tue, 31 Mar 2020 15:58:24 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jJJHT-0007Lx-VC for xen-devel@lists.xenproject.org; Tue, 31 Mar 2020 15:58:23 +0000 X-Inumbo-ID: 72ee9c80-7368-11ea-b58d-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 72ee9c80-7368-11ea-b58d-bc764e2007e4; Tue, 31 Mar 2020 15:58:23 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 9D9D3AE4B; Tue, 31 Mar 2020 15:58:22 +0000 (UTC) Subject: [PATCH v2 1/2] x86emul: vendor specific SYSCALL behavior From: Jan Beulich To: "xen-devel@lists.xenproject.org" References: Message-ID: Date: Tue, 31 Mar 2020 17:58:14 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Andrew Cooper , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" AMD CPUs permit the insn everywhere (even outside of protected mode), while Intel ones restrict it to 64-bit mode. While at it also comment about the apparently missing CPUID bit check. Signed-off-by: Jan Beulich --- v2: Replace CPUID bit check by comment. --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -5897,13 +5897,16 @@ x86_emulate( break; case X86EMUL_OPC(0x0f, 0x05): /* syscall */ - generate_exception_if(!in_protmode(ctxt, ops), EXC_UD); - - /* Inject #UD if syscall/sysret are disabled. */ + /* + * Inject #UD if syscall/sysret are disabled. EFER.SCE can't be set + * with the respective CPUID bit clear, so no need for an explicit + * check of that one. + */ fail_if(ops->read_msr == NULL); if ( (rc = ops->read_msr(MSR_EFER, &msr_val, ctxt)) != X86EMUL_OKAY ) goto done; generate_exception_if((msr_val & EFER_SCE) == 0, EXC_UD); + generate_exception_if(!amd_like(ctxt) && !mode_64bit(), EXC_UD); if ( (rc = ops->read_msr(MSR_STAR, &msr_val, ctxt)) != X86EMUL_OKAY ) goto done;