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 6CB09C433E0 for ; Thu, 21 Jan 2021 22:37:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2808923A60 for ; Thu, 21 Jan 2021 22:37:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726885AbhAUWgw (ORCPT ); Thu, 21 Jan 2021 17:36:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726822AbhAUWgp (ORCPT ); Thu, 21 Jan 2021 17:36:45 -0500 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC3FBC06174A for ; Thu, 21 Jan 2021 14:35:59 -0800 (PST) Received: by mail-pl1-x62c.google.com with SMTP id e9so2139923plh.3 for ; Thu, 21 Jan 2021 14:35:59 -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=HtagZa2utrgVZ8EO6yL1vWOFCbFLgOv3ljBb8Jq8YdU=; b=Om26hhxJRyeJ93IrXhZROKDhjJ435IRJbXSbYJ9gSBnBiQA9i5yA2UijRT0/ySX5PV 9OPjibb0E9cXZ1Zhi3X8QiU1Ul5O2PnP0PrjmfErqKyNyWnciScr6CNCJCClOA4HNcRn pwWXfmVd31iUFZbBBeDsDaPESk6SzLx9Qy0ziyzrOlYYvOkQXZ9aO5qYMcgqFnhmtQ7m 4BDdXB1qh6TCVbPzDA2iDzKQJpN6MLBZvXwA4QtV4k0QeEJyfgLy6T65ObT1Mgvb5io+ 26m2v0/SGWMvU+XgN6S1ONunh7VjIFofo8yN7WJirTCPGpoQ+PdKn7XRBbMtD2BkgWS0 tlRA== 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=HtagZa2utrgVZ8EO6yL1vWOFCbFLgOv3ljBb8Jq8YdU=; b=OqkOEbJVtYG3BztG7FjNDwlXQfgOKaBTU1fooCMFe7UFyGr5uHAVNMduWklJ3bupIz g5TAbwh+a/rVEoJu8Uvh6aDMPNqs0Jog6ekXRO7tk2vjPotUuwUZQ0DlP+IRbEn4Vpl6 ViUsoJzzHKBTMKZP1ptGzieXM0hBgMyM87wXkHy4f2xKccK3LROgj7ZqKbweP6Px8twm 7ItqPjDJu+Hwn6CJyqa16Orjm5UVi2CND2mbz5KQN1sRda6rmqo/omB2K17dg8YsI/B4 Cdg3sy6kkVkiNPLjSc1C3qQp8V96u+44XIVKBi6BS/xA5+athZH5Sq0D3cVMxJ8E4GBV UnsA== X-Gm-Message-State: AOAM531ZnR9D4P4OcYRq5ehwKqF1DQwL+R2eYacL8JPtTaQq2Pl/7uWc eGGhQN7q9eTByJsfoqbP+Tm1uA== X-Google-Smtp-Source: ABdhPJy9LJ57DCr4V2SGC+Z1NTqWzTbxrQqJBoge5bsU6nlW8rd+uk0CG9BE7uEtO2imrj7na0H7zA== X-Received: by 2002:a17:903:248b:b029:de:9885:d1fa with SMTP id p11-20020a170903248bb02900de9885d1famr1583550plw.77.1611268559000; Thu, 21 Jan 2021 14:35:59 -0800 (PST) Received: from google.com ([2620:15c:f:10:1ea0:b8ff:fe73:50f5]) by smtp.gmail.com with ESMTPSA id j10sm6973556pjy.9.2021.01.21.14.35.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Jan 2021 14:35:58 -0800 (PST) Date: Thu, 21 Jan 2021 14:35:51 -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> <20210121165845.GD32060@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210121165845.GD32060@zn.tnic> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 21, 2021, Borislav Petkov wrote: > On Mon, Dec 28, 2020 at 11:15:11AM -0800, Sean Christopherson wrote: > > 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. > > Personal Firearms Eligibility Check? Ha, Page Fault Error Code. > In any case, I prefer simple, easy to follow code at a quick glance. > Stuff like... > > > > > 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)) > > ... this second repeated check here is not what I would call that. But then you're stuck maintaining two separate flows that do the same thing. > But this is my personal preference only so it's up for a vote now. Rock Paper Scissors?