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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 BF06EC43216 for ; Wed, 28 Jul 2021 13:19:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5B1D6101B for ; Wed, 28 Jul 2021 13:19:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236153AbhG1NTT (ORCPT ); Wed, 28 Jul 2021 09:19:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234771AbhG1NTS (ORCPT ); Wed, 28 Jul 2021 09:19:18 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8295AC061757; Wed, 28 Jul 2021 06:19:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=bU/Ms46JtnXaVrVhQUyi3qsSgcv2ZUBgkJZ69baP/Pk=; b=l/t/Xn+txpO1+X8wtS8Uk4aaqG m2+T0SHpVqEnt0/9mZr65K2ueB1kLi0Gx/E9Ov/NZNfcfbm0aSIoCXUBZDMdD7FMkHtRpiECduJr7 Rt4ArgG6CcLFJpfB7mhR9ochKMyUK4sUQhYvpLwmW49Gs9J06Mvyg5y94GM6d6rLaXR9BaAbWOIpZ 10T8RMs/K27IkXLp/vjCX+SQ8wtLiH+hDMOJw4D/h2g1l8zP6PGPE8V75qPmB6DklI1zsDwON4VTT tuN/D97KN3CBoRNqQG3rooTGaJ8SPBZlGmhA5MCb/K3ZPko/3eWBLi9x75g/uvwD+FrvCC64M+RgR Pk0dHV9A==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8jR9-00G4xh-78; Wed, 28 Jul 2021 13:17:52 +0000 Date: Wed, 28 Jul 2021 14:17:27 +0100 From: Christoph Hellwig To: Tom Lendacky Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-graphics-maintainer@vmware.com, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, Andi Kleen , Tianyu Lan , Borislav Petkov , Brijesh Singh Subject: Re: [PATCH 01/11] mm: Introduce a function to check for virtualization protection features Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 27, 2021 at 05:26:04PM -0500, Tom Lendacky via iommu wrote: > In prep for other protected virtualization technologies, introduce a > generic helper function, prot_guest_has(), that can be used to check > for specific protection attributes, like memory encryption. This is > intended to eliminate having to add multiple technology-specific checks > to the code (e.g. if (sev_active() || tdx_active())). So common checks obviously make sense, but I really hate the stupid multiplexer. Having one well-documented helper per feature is much easier to follow. > +#define PATTR_MEM_ENCRYPT 0 /* Encrypted memory */ > +#define PATTR_HOST_MEM_ENCRYPT 1 /* Host encrypted memory */ > +#define PATTR_GUEST_MEM_ENCRYPT 2 /* Guest encrypted memory */ > +#define PATTR_GUEST_PROT_STATE 3 /* Guest encrypted state */ The kerneldoc comments on these individual helpers will give you plenty of space to properly document what they indicate and what a (potential) caller should do based on them. Something the above comments completely fail to.