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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 A38FACDB47E for ; Fri, 13 Oct 2023 15:28:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=c2mddrftow7yQXzBBt7dMsN1cuXC63XEROhpASH5uIc=; b=Mp2YIZbDBxAVOi T3Pr723i4uMWoV7rft5fWiipC2Bc1TY5iyfHA6uogf1MRgrHJEucEt5P9+TFIkFi52z5CYhWu21D6 4Ce9QSKKeXLLSVKAJN9yrv2XfOUuqJ7AW8vjR4ABfH32P+R0orgNxIsnQOEmqEIYdG3lPrD1OeLJ2 C6JHQzuoVykbCgOhIxfnnTLCfGhboJStVutUTe0aVGUkikWV/DF6Vs63Lkg4sAMk0uU+dIdbg+Y5e jK1OK5P6KXwec2XR0p0ZHpebRdDOvshfz2BgFSFt4oHilTjTcQn9rOUrG/IdBEy7xqSx5rsW5Q3yd Krw6EgH4snyt+svrDTfw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qrK5O-003gAV-2g; Fri, 13 Oct 2023 15:28:22 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qrK5M-003g97-0g for linux-arm-kernel@lists.infradead.org; Fri, 13 Oct 2023 15:28:21 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id 155CBB82A67; Fri, 13 Oct 2023 15:28:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E84CC433C8; Fri, 13 Oct 2023 15:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697210897; bh=iiew/laD+Q3haHwMxgaUmOJOpF//XuI1aJ4hOlOKh6s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=B6aOhjI4W3T3qqRBW/NsttzXu5HUYLUV0lP13HpcxULbCsY8haM+fvx/hkj6ifjtz 5uZCpSp2yYae/IoUGpnXO1b3PAiCRuxJ2QNmSgt762IP05AQmV1jLJKNvfC3fo3Nff Z1eyDfRCPYIEucr4zoADjXI4vRzVrqegikLNsl094KykJc8hZMs9isjWNn37ugG4mL b7BS7rV1TDFjqx3xH9xB/2V45Bkqj8K5qirF/WyXBzb1dv9lhsMC7rfYLnjJAqVQfh xNspCeaor9aeIXP83je9bdwKF47wno/dy555mpvKuCdCi1hRXBYmhqlW+lJOw1Ar8m CQCLt2ppkzeJA== Date: Fri, 13 Oct 2023 17:28:10 +0200 From: Lorenzo Pieralisi To: Catalin Marinas Cc: Will Deacon , Jason Gunthorpe , ankita@nvidia.com, maz@kernel.org, oliver.upton@linux.dev, aniketa@nvidia.com, cjia@nvidia.com, kwankhede@nvidia.com, targupta@nvidia.com, vsethi@nvidia.com, acurrid@nvidia.com, apopple@nvidia.com, jhubbard@nvidia.com, danw@nvidia.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 2/2] KVM: arm64: allow the VM to select DEVICE_* and NORMAL_NC for IO memory Message-ID: References: <20231012123541.GB11824@willie-the-truck> <20231012144807.GA12374@willie-the-truck> <20231013092934.GA13524@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231013_082820_395026_66C8C034 X-CRM114-Status: GOOD ( 15.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 13, 2023 at 02:08:10PM +0100, Catalin Marinas wrote: [...] > Yes, we end up with mismatched aliases but they only matter if the VMM > also accesses the I/O range via its own mapping. So far I haven't seen > case that suggests this. > > > > Things can go wrong but that's not because Device does anything better. > > > Given the RAS implementation, external aborts caused on Device memory > > > (e.g. wrong size access) is uncontainable. For Normal NC it can be > > > contained (I can dig out the reasoning behind this if you want, IIUC > > > something to do with not being able to cancel an already issued Device > > > access since such accesses don't allow speculation due to side-effects; > > > for Normal NC, it's just about the software not getting the data). > > > > I really think these details belong in the commit message. > > I guess another task for Lorenzo ;). I will do, I start wondering though whether this documentation belongs in this commit log only or at Documentation/arch/arm64 level (or both), I am pretty sure this thread can turn out quite useful as a reference (it is for me) if we manage to summarize it that would benefit everyone. Lorenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel