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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A2BEC4167B for ; Tue, 5 Dec 2023 17:33:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346173AbjLERdE (ORCPT ); Tue, 5 Dec 2023 12:33:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346120AbjLERdC (ORCPT ); Tue, 5 Dec 2023 12:33:02 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B54481B9 for ; Tue, 5 Dec 2023 09:33:08 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AC45C433C8; Tue, 5 Dec 2023 17:33:03 +0000 (UTC) Date: Tue, 5 Dec 2023 17:33:01 +0000 From: Catalin Marinas To: Marc Zyngier Cc: Jason Gunthorpe , 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, lpieralisi@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> <20231205164318.GG2692119@nvidia.com> <86bkb4bn2v.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86bkb4bn2v.wl-maz@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 05, 2023 at 05:01:28PM +0000, Marc Zyngier wrote: > On Tue, 05 Dec 2023 16:43:18 +0000, > Jason Gunthorpe wrote: > > On Tue, Dec 05, 2023 at 04:22:33PM +0000, Catalin Marinas wrote: > > > That's an argument to restrict this feature to PCIe. It's really about > > > fewer arguments on the behaviour of other devices. Marc did raise > > > another issue with the GIC VCPU interface (does this even have a vma in > > > the host VMM?). That's a class of devices where the mapping is > > > context-switched, so the TLBI+DSB rules don't help. > > There is no vma. The CPU interface is entirely under control of KVM. > Userspace only provides the IPA for the mapping. That's good to know. We can solve the GIC issue by limiting the relaxation to those mappings that have a user vma. Ideally we should do this for vfio only but we don't have an easy way to convey this to KVM. -- Catalin