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 E3949C4167B for ; Tue, 5 Dec 2023 16:25:06 +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=fAfr780Bs3Xbs50mUT0sgC1aDYvpA8JctrIbYFMrFBo=; b=zCB3pzAG0rVjD8 3wcRDwbu3HJrXhJt4FbY0fD/7EpB2VutuMdVBPeFsdA1RjVrAG0H9b3ny4qgy8v9XFmWbpmCifZCy 5rzzazsnO+yH4DgXxqZ9OsK2bwsQFDvDC4IqDqmeM96npxWG7UkKWEB+Uxg/F9/RcqlGzlB/tJWVZ KbXNz38QJE2tQejiKsF8hkU6Sh9FvCYUDODFITpbataJ4R8tRMRa1TLtshoQfbTn+q/rKvz8D0kxG UjPb9BOCjS/RJOURW2Z3WV+XOiTjcW/33by6farFQyx9ukXl1X1dVwNFp97iH13dX7jonePGzbxh9 dDYhsYggj/LMBwX9XL0Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rAYDr-007s08-2f; Tue, 05 Dec 2023 16:24:35 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rAYDo-007ryx-16 for linux-arm-kernel@lists.infradead.org; Tue, 05 Dec 2023 16:24:33 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id A7A30B81A29; Tue, 5 Dec 2023 16:24:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D01CC433C8; Tue, 5 Dec 2023 16:24:25 +0000 (UTC) Date: Tue, 5 Dec 2023 16:24:22 +0000 From: Catalin Marinas To: Jason Gunthorpe Cc: Lorenzo Pieralisi , Marc Zyngier , ankita@nvidia.com, Shameerali Kolothum Thodi , oliver.upton@linux.dev, suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org, ardb@kernel.org, akpm@linux-foundation.org, gshan@redhat.com, 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, mochs@nvidia.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 1/1] KVM: arm64: allow the VM to select DEVICE_* and NORMAL_NC for IO memory Message-ID: References: <20231205033015.10044-1-ankita@nvidia.com> <86fs0hatt3.wl-maz@kernel.org> <20231205130517.GD2692119@nvidia.com> <20231205144417.GE2692119@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231205144417.GE2692119@nvidia.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231205_082432_508289_3B5EF37B X-CRM114-Status: GOOD ( 22.49 ) 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 Tue, Dec 05, 2023 at 10:44:17AM -0400, Jason Gunthorpe wrote: > On Tue, Dec 05, 2023 at 03:37:13PM +0100, Lorenzo Pieralisi wrote: > > On Tue, Dec 05, 2023 at 09:05:17AM -0400, Jason Gunthorpe wrote: > > > On Tue, Dec 05, 2023 at 11:40:47AM +0000, Catalin Marinas wrote: > > > > > - Will had unanswered questions in another part of the thread: > > > > > > > > > > https://lore.kernel.org/all/20231013092954.GB13524@willie-the-truck/ > > > > > > > > > > Can someone please help concluding it? > > > > > > > > Is this about reclaiming the device? I think we concluded that we can't > > > > generalise this beyond PCIe, though not sure there was any formal > > > > statement to that thread. The other point Will had was around stating > > > > in the commit message why we only relax this to Normal NC. I haven't > > > > checked the commit message yet, it needs careful reading ;). > > > > > > Not quite, we said reclaiming is VFIO's problem and if VFIO can't > > > reliably reclaim a device it shouldn't create it in the first place. > > > > I think that as far as device reclaiming was concerned the question > > posed was related to memory attributes of transactions for guest > > mappings and the related grouping/ordering with device reset MMIO > > transactions - it was not (or wasn't only) about error containment. > > Yes. It is VFIO that issues the reset, it is VFIO that must provide > the ordering under the assumption that NORMAL_NC was used. And does it? Because VFIO so far only assumes Device-nGnRnE. Do we need to address this first before attempting to change KVM? Sorry, just questions, trying to clear the roadblocks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel