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 31A40C10DCE for ; Wed, 6 Dec 2023 11:54:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378078AbjLFLxw (ORCPT ); Wed, 6 Dec 2023 06:53:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377869AbjLFLxe (ORCPT ); Wed, 6 Dec 2023 06:53:34 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E133F18F for ; Wed, 6 Dec 2023 03:52:31 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CFF0C433C7; Wed, 6 Dec 2023 11:52:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701863551; bh=05fhoFGytrb/RJVFsqCfWb/MpYZO3vCszNXvCTYOi5I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=m8uHeg6+sgeVDfycKFuNZurfjPt2fm+n6wDkQ2SIs7zyPppjfdb2wm1va/48JA0TP I1W704/kf75kVpMltgXOgSY4eseh24mIbw19LRFUEJVfd/c/wmYe73odbLOo/5XmWX sFcS/mGGxs7HRYLdErEeAbyFTFMqvKU9uCzB/Wrx6ZCMM0RFZ+vyMOQ7ZydeeB9h6U qxpC1YE4z6o1/Vy43ZMxA6Ct+J67pShbtcOqSkrV/7VbsWnQfFvHsFkflCcy+2+H6I WJmjaPF+/BQfCb6TPQDsXEDG9egNaA5cy6ZqmGOCw1m3ktAdpIY36JlLT+BfUYxlpL FCpOHg+/KS0Qg== Date: Wed, 6 Dec 2023 12:52:22 +0100 From: Lorenzo Pieralisi To: Catalin Marinas Cc: Marc Zyngier , 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, 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> <86a5qobkt8.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 05, 2023 at 06:40:42PM +0000, Catalin Marinas wrote: > On Tue, Dec 05, 2023 at 05:50:27PM +0000, Marc Zyngier wrote: > > On Tue, 05 Dec 2023 17:33:01 +0000, > > Catalin Marinas wrote: > > > Ideally we should do this for vfio only but we don't have an easy > > > way to convey this to KVM. > > > > But if we want to limit this to PCIe, we'll have to find out. The > > initial proposal (a long while ago) had a flag conveying some > > information, and I'd definitely feel more confident having something > > like that. > > We can add a VM_PCI_IO in the high vma flags to be set by > vfio_pci_core_mmap(), though it limits it to 64-bit architectures. KVM > knows this is PCI and relaxes things a bit. It's not generic though if > we need this later for something else. > > A question for Lorenzo: do these BARs appear in iomem_resource? We could > search that up instead of a flag, something like the page_is_ram() > helper. They do but an iomem_resource look-up alone if I am not mistaken would not tell us if it is PCI address space, we would need additional checks (like detecting if we are decoding an address within a PCI host bridge windows) to determine that if we go down this route. Lorenzo