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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 F4055C433DB for ; Mon, 28 Dec 2020 19:16:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9A5922B2A for ; Mon, 28 Dec 2020 19:16:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729144AbgL1TQB (ORCPT ); Mon, 28 Dec 2020 14:16:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727771AbgL1TP7 (ORCPT ); Mon, 28 Dec 2020 14:15:59 -0500 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84C40C0613D6 for ; Mon, 28 Dec 2020 11:15:19 -0800 (PST) Received: by mail-pf1-x431.google.com with SMTP id s21so6723422pfu.13 for ; Mon, 28 Dec 2020 11:15:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=dHeCf8u1kCKbyNn5Y3Ab2K3Prk73t7dYCKJ4U5bk5mY=; b=mwWB2wmAXbVaif+qgz5KbyzLJgwgX4AKLDrPzjqjy2xC9sN4gszjAIzM9iG5rSE4v7 F34rHAX0HoomHOMONzkC+hkTkDr1I+X819iLbYWcFRCLsdrLb2fqiXUWWSEcW5GAAFmU mKU00va7UowFOgU54oj57OPxF3ESz4VjunalFYccqyel1U4yuLzvWZwXHbZi2fQtif2w a2pKiFnRqWcj5uBvK87q3PGR5Xl2U/80BGwwUhcY6vYKFEImqO3M9knBXAbEkd6v35QN f37mrguF99sKWBr7FA6cV5XLAGCuLrDNSdIS0ZpuUwMGKJoKq57RRdnnm9zx9Bs+8kWU uc5g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=dHeCf8u1kCKbyNn5Y3Ab2K3Prk73t7dYCKJ4U5bk5mY=; b=q1A2iuDLHmcBOdprMiszjpsMU40ahOaqJO6bufnVspYPzdj5To4MsC4gjeEKt0g9WL olh+9RyjcmXfpbeyzB1hrgf1lZSTtYNqwv6iIMF6Cp5TavcF3Op0INgI1GjwgI6UQ3j/ 3vSzrOgQQavR6QtEGOsoG9XiNxIJePkNGUM9C8wPdRZMcZjui/pncUx7AWDq4usKM/rx aoVpbq54MWGosHOKFTlqkU1JvEgeS0gK1u0z6HN1DcZpldjj633LQOqkrMoM5btGLbSl wjHXbIrXYmLCFsT3MuZ12SJlb8mNWN/n9t0MO/pWCbCmPWyLrXYmfUPBEIghcY6h2+gX 2pTw== X-Gm-Message-State: AOAM531tNMNVEhw6XMqD06MqZxH5qYope3MUCz+IA4CcxuwWVA2NTtIw +5tI/EQCFbswm7mViFmohsOcbA== X-Google-Smtp-Source: ABdhPJyVZ8ZFWqN1fhk+9rjIzNooZfqCl5c/hbj36SAoln35h/HbESlR5jAnqk+8zLNob8kWGFS5Rg== X-Received: by 2002:a63:6e45:: with SMTP id j66mr45424795pgc.238.1609182918866; Mon, 28 Dec 2020 11:15:18 -0800 (PST) Received: from google.com ([2620:15c:f:10:1ea0:b8ff:fe73:50f5]) by smtp.gmail.com with ESMTPSA id f7sm171551pjs.25.2020.12.28.11.15.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Dec 2020 11:15:18 -0800 (PST) Date: Mon, 28 Dec 2020 11:15:11 -0800 From: Sean Christopherson To: Borislav Petkov Cc: kernel test robot , Andy Lutomirski , Masami Hiramatsu , kbuild-all@lists.01.org, clang-built-linux@googlegroups.com, X86 ML , LKML Subject: Re: [PATCH v1 11/19] x86/sev-es: Convert to insn_decode() Message-ID: References: <20201223174233.28638-12-bp@alien8.de> <202012251838.G6eufP3Q-lkp@intel.com> <20201225123334.GA5874@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201225123334.GA5874@zn.tnic> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 25, 2020, Borislav Petkov wrote: > On Fri, Dec 25, 2020 at 06:50:33PM +0800, kernel test robot wrote: > > If you fix the issue, kindly add following tag as appropriate > > Reported-by: kernel test robot > > > > All warnings (new ones prefixed by >>): > > > > >> arch/x86/kernel/sev-es.c:258:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] > > if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, res)) > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Yeah, good catch, thanks for reporting. > > Frankly, the readability and "extensiblity" of that function can be > improved by splitting the two cases (diff ontop): Alternatively, could the kernel case use insn_decode_regs()? If vc_fetch_insn_kernel() were also modified to mirror insn_fetch_from_user(), the two code paths could be unified except for the the fetch and the PFEC. E.g. static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt, unsigned char *buffer) { if (copy_from_kernel_nofault(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE)) return 0; return MAX_INSN_SIZE; } static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt) { char buffer[MAX_INSN_SIZE]; int nbytes; if (user_mode(ctxt->regs)) nbytes = insn_fetch_from_user(ctxt->regs, buffer); else nbytes = vc_fetch_insn_kernel(ctxt, buffer); if (!nbytes) { ctxt->fi.vector = X86_TRAP_PF; ctxt->fi.error_code = X86_PF_INSTR; if (user_mode(ctxt->regs)) ctxt->fi.error_code |= X86_PF_USER; ctxt->fi.cr2 = ctxt->regs->ip; return ES_EXCEPTION; } if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, nbytes)) return ES_DECODE_FAILED; return ctxt->insn.immediate.got ? ES_OK : ES_DECODE_FAILED; }