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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 73FE1C27C53 for ; Wed, 12 Jun 2024 15:27:31 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.739449.1146484 (Exim 4.92) (envelope-from ) id 1sHPsg-0003mL-6f; Wed, 12 Jun 2024 15:27:22 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 739449.1146484; Wed, 12 Jun 2024 15:27:22 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1sHPsg-0003mE-3t; Wed, 12 Jun 2024 15:27:22 +0000 Received: by outflank-mailman (input) for mailman id 739449; Wed, 12 Jun 2024 15:27:21 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1sHPsf-0003m8-3W for xen-devel@lists.xenproject.org; Wed, 12 Jun 2024 15:27:21 +0000 Received: from mail-qt1-x829.google.com (mail-qt1-x829.google.com [2607:f8b0:4864:20::829]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 41e20d5c-28d0-11ef-90a3-e314d9c70b13; Wed, 12 Jun 2024 17:27:20 +0200 (CEST) Received: by mail-qt1-x829.google.com with SMTP id d75a77b69052e-44054a2c153so12915831cf.2 for ; Wed, 12 Jun 2024 08:27:20 -0700 (PDT) Received: from localhost ([213.195.124.163]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-441136b1d16sm23245271cf.25.2024.06.12.08.27.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Jun 2024 08:27:18 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 41e20d5c-28d0-11ef-90a3-e314d9c70b13 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1718206039; x=1718810839; darn=lists.xenproject.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=A94detY1UyHmoOWbBrK/++zmK7b8qtAxB+K8E9DexK0=; b=DekJgvxwYZYc0hQx+nzw5cxo3sKybwBWZ4NDDZBJqC/EmRNZ2tigSfF61qyIqxehE8 Ngi2IqpIQe8A7ySkwGqTTk+MKpOgeHhIN41r6oRVhflDTq5ipE73+WjSsqZdxnoiqoXl Wu3B3g6yZmXfmSAxa7QqlYCtIPel/Jr7f0Gig= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718206039; x=1718810839; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=A94detY1UyHmoOWbBrK/++zmK7b8qtAxB+K8E9DexK0=; b=EpKx+jmJc6A+JpIvksxSA/USUG4YcsBGC4yFS909XPOWiarFp8050RH/QawDyG9U1z wqswsG8jFVWKgZika+kpX9zyMv5MDkq2h1B84UoVJeHzoyFVFMI+i8UyowHOMdyJ2dy3 RtgI4ub+oxbOARuVMMM7C1YUuJ0SsIty5kcsI8Luc0OWTJwM0Ov8C+JdPPRcTCD2TSjE gN4uMlu5BmfoZpnMm3mTq2HNXpVwIJm0CWL2VOWylX7LlJq6tFymJ+wyst6O7aR2xll2 KKiFMkIdqP/J4IHedM/MOSIvH4n7qp5J3JBwW2B1bOaL/KeCaSnszpgLRQgswkmRceip 1uoQ== X-Gm-Message-State: AOJu0YzAIAiAPf5jEG+QHYVczZp/lyNu1vpR4bcOnuO+jwHsRSU6sChf u+oprFrA1byo9aqklhN2wjO02cpOsj8FG00EF/j6LDlzXTT/a2oA/CaNyuPPWoU= X-Google-Smtp-Source: AGHT+IHCiLpJPetdyLh9zWdcFF+M9fI61y5Jh1ibc8wrGCrLx/bJXxIXC1Ap0CC5Y1OC2DXC/g/bPQ== X-Received: by 2002:ac8:7f10:0:b0:441:58e9:678d with SMTP id d75a77b69052e-4415ac6e056mr20030781cf.64.1718206039065; Wed, 12 Jun 2024 08:27:19 -0700 (PDT) Date: Wed, 12 Jun 2024 17:27:16 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper , Oleksii Kurochko Subject: Re: [PATCH v2 for-4.19 3/3] x86/EPT: drop questionable mfn_valid() from epte_get_entry_emt() Message-ID: References: <2936ffad-5395-45fd-877f-7fb2ca8b9dc8@suse.com> <7607c5f7-772a-4c49-b2df-19f32ec2180b@suse.com> <07d38484-dda3-4494-9dbb-75d4d2dbc3c3@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <07d38484-dda3-4494-9dbb-75d4d2dbc3c3@suse.com> On Wed, Jun 12, 2024 at 05:14:37PM +0200, Jan Beulich wrote: > On 12.06.2024 17:00, Roger Pau Monné wrote: > > I wonder if you should explicitly mention that if adding the > > mfn_valid() check was done to ensure all mappings to MMIO are created > > with effective UC caching attribute it won't be fully correct either. > > Xen could map those using a different effective caching attribute by > > virtue of host MTRRs being in effect plus Xen chosen PAT attributes. > > Well, the mfn_valid() can't have been there to cover _all_ MMIO. It was > maybe a flawed initial attempt at doing so, and then wasn't properly > adjusted / dropped. So overall - no, I don't think extending the > description with anything along the lines of the above would make a lot > of sense. I realized myself when writing the paragraph that I wouldn't even know how to word it properly, neither it would be much helpful without knowing the exact intention the mfn_valid() check was added for. Thanks, Roger.