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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C804DC433E1 for ; Tue, 23 Jun 2020 15:06:35 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 99B922073E for ; Tue, 23 Jun 2020 15:06:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="xVjpdZuw"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uyCRgzzn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 99B922073E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID:Subject:To:From: Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References:List-Owner; bh=znI9LqNJPgb5fMABrOztgOTZ4vf/HurJixy6La83rNw=; b=xVjpdZuwj8Gv+jH/vATQMq77E tZGF8VrNfQLHFKNq0IkkD5V+OboZkOrFhmBIruBgf7TyI7XuW3CWhgxulei+ZKRjwtHYDZd/VZ4jF LdcvQJjjhLCoZbGEztG8rynFm4l7JXQpC7WsH4cn28JfhV1prgy3kT6o8c3OkQuYZz/dcIITd3CDT oUzPIEZn4XLs7g1PBAfxqrfKGbtpjwMfo+0YfulgKK9Ca3iyqDuhnAYrwtfO2i5vTh7x16p2vGg09 iz+kOAlzz/hJRyIFvmAFzzrNbXk2hD0JglqWI8YX6OEGRqo53gLSXs0gGoqYybU90hwcms8xUPtrt lVM36JZCQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jnkTU-0006EM-BG; Tue, 23 Jun 2020 15:04:36 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jnkTN-0006C3-J4 for linux-arm-kernel@lists.infradead.org; Tue, 23 Jun 2020 15:04:31 +0000 Received: from localhost (mobile-166-170-222-206.mycingular.net [166.170.222.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 94EC420723; Tue, 23 Jun 2020 15:04:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592924669; bh=pYSmEX90OpGgB4bw3JQlLwOPKGPZt8zcCg2Jw+YWJhM=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=uyCRgzznNIaGzwTA5WSAD0mfkUx7PWjjDA0xuNRfK8wdFyqid6COQmfVRcULXo7eB x6r9H+xRROcynvqijhjGKwufYcigaaHtOMvN1NklZTodXP7DkrU83liurSsGCNLFtO sRrkKEDXRbWwc9kz0no38z13LtKl0kt/Ne0JEuNE= Date: Tue, 23 Jun 2020 10:04:27 -0500 From: Bjorn Helgaas To: Zhangfei Gao Subject: Re: [PATCH 0/2] Introduce PCI_FIXUP_IOMMU Message-ID: <20200623150427.GA2403606@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-pci , Hanjun Guo , jean-philippe , Lorenzo Pieralisi , Herbert Xu , Joerg Roedel , Wangzhou , ACPI Devel Maling List , Linux ARM , Len Brown , Thanu Rangarajan , Souvik Chakravarty , Arnd Bergmann , Bjorn Helgaas , wanghuiqiang , kenneth-lee-2012@foxmail.com, Greg Kroah-Hartman , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , "open list:IOMMU DRIVERS" , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , Sudeep Holla Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jun 19, 2020 at 10:26:54AM +0800, Zhangfei Gao wrote: > Have studied _DSM method, two issues we met comparing using quirk. > = > 1. Need change definition of either pci_host_bridge or pci_dev, like addi= ng > member can_stall, > while pci system does not know stall now. > = > a, pci devices do not have uuid: uuid need be described in dsdt, while pci > devices are not defined in dsdt. > =A0=A0=A0 so we have to use host bridge. PCI devices *can* be described in the DSDT. IIUC these particular devices are hardwired (not plug-in cards), so platform firmware can know about them and could describe them in the DSDT. > b,=A0 Parsing dsdt is in in pci subsystem. > Like drivers/acpi/pci_root.c: > =A0=A0=A0=A0=A0=A0 obj =3D acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), &p= ci_acpi_dsm_guid, > 1, > =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0 IGNORE_PCI_BOOT_CONFIG_DSM, NULL); > = > After parsing DSM in pci, we need record this info. > Currently, can_stall info is recorded in iommu_fwspec, > which is allocated in iommu_fwspec_init and called by iort_iommu_configure > for uefi. You can look for a _DSM wherever it is convenient for you. It could be in an AMBA shim layer. > 2. Guest kernel also need support sva. > Using quirk, the guest can boot with sva enabled, since quirk is > self-contained by kernel. > If using=A0 _DSM, a specific uefi or dtb has to be provided, > currently we can useQEMU_EFI.fd from apt install qemu-efi I don't quite understand what this means, but as I mentioned before, a quirk for a *limited* number of devices is OK, as long as there is a plan that removes the need for a quirk for future devices. E.g., if the next platform version ships with a DTB or firmware with a _DSM or other mechanism that enables the kernel to discover this information without a kernel change, it's fine to use a quirk to cover the early platform. The principles are: - I don't want to have to update a quirk for every new Device ID that needs this. - I don't really want to have to manage non-PCI information in the struct pci_dev. If this is AMBA- or IOMMU-related, it should be stored in a structure related to AMBA or the IOMMU. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel