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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 24309C4743D for ; Fri, 4 Jun 2021 19:04:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 033EB6140F for ; Fri, 4 Jun 2021 19:04:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230022AbhFDTGT (ORCPT ); Fri, 4 Jun 2021 15:06:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:49450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229810AbhFDTGT (ORCPT ); Fri, 4 Jun 2021 15:06:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4AE5B601FA; Fri, 4 Jun 2021 19:04:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622833472; bh=cer+Bvra6ed4Y1JhppV0+conxTw5XnnGzF6r3B03UOU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=Pgs6fH6TcnnUw8hfgWKlTOSTVfaEuwrfVRR8ujvSBTO324x6uWtuGOckoBCpzJ7Cb /wzC0Ws51l1cn/h0+mHDypRuLpORZWRkK2rN6n7inGVpTy0sIOtSEXE6TY7iUrtQNv IUbVAs85WZLnsAkjma8Xxz5Bl0Qjb/iTQTSAYHDUWXSfU/U6tDwXaZcC/SWh9T9F8y BZyhgWZxGfSS21qyebdNulqatlFqmMZx9cyuQjVNQpkXXgzIsy+i4lV/jxM98CNFYp 40mrZty5gLW8tBI/pwa+/em5NIcUR1AWXQh8Yny2fywHYDvi1pGqGlh36R+RCqF3Qx RsgLqKfpASVOA== Date: Fri, 4 Jun 2021 14:04:30 -0500 From: Bjorn Helgaas To: Wang Xingang Cc: robh@kernel.org, will@kernel.org, joro@8bytes.org, robh+dt@kernel.org, gregkh@linuxfoundation.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, xieyingtai@huawei.com, John Garry Subject: Re: [PATCH v4] iommu/of: Fix pci_request_acs() before enumerating PCI devices Message-ID: <20210604190430.GA2220179@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1621566204-37456-1-git-send-email-wangxingang5@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org [+cc John, who tested 6bf6c24720d3] On Fri, May 21, 2021 at 03:03:24AM +0000, Wang Xingang wrote: > From: Xingang Wang > > When booting with devicetree, the pci_request_acs() is called after the > enumeration and initialization of PCI devices, thus the ACS is not > enabled. And ACS should be enabled when IOMMU is detected for the > PCI host bridge, so add check for IOMMU before probe of PCI host and call > pci_request_acs() to make sure ACS will be enabled when enumerating PCI > devices. I'm happy to apply this, but I'm a little puzzled about 6bf6c24720d3 ("iommu/of: Request ACS from the PCI core when configuring IOMMU linkage"). It was tested and fixed a problem, but I don't understand how. 6bf6c24720d3 added the call to pci_request_acs() in of_iommu_configure() so it currently looks like this: of_iommu_configure(dev, ...) { if (dev_is_pci(dev)) pci_request_acs(); pci_request_acs() sets pci_acs_enable, which tells us to enable ACS when enumerating PCI devices in the future. But we only call pci_request_acs() if we already *have* a PCI device. So maybe 6bf6c24720d3 fixed a problem for *some* PCI devices, but not all? E.g., did we call of_iommu_configure() for one PCI device before enumerating the rest? > Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when > configuring IOMMU linkage") > Signed-off-by: Xingang Wang > --- > drivers/iommu/of_iommu.c | 1 - > drivers/pci/of.c | 8 +++++++- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index a9d2df001149..54a14da242cc 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, > .np = master_np, > }; > > - pci_request_acs(); > err = pci_for_each_dma_alias(to_pci_dev(dev), > of_pci_iommu_init, &info); > } else { > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > index da5b414d585a..2313c3f848b0 100644 > --- a/drivers/pci/of.c > +++ b/drivers/pci/of.c > @@ -581,9 +581,15 @@ static int pci_parse_request_of_pci_ranges(struct device *dev, > > int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge) > { > - if (!dev->of_node) > + struct device_node *node = dev->of_node; > + > + if (!node) > return 0; > > + /* Detect IOMMU and make sure ACS will be enabled */ > + if (of_property_read_bool(node, "iommu-map")) > + pci_request_acs(); > + > bridge->swizzle_irq = pci_common_swizzle; > bridge->map_irq = of_irq_parse_and_map_pci; > > -- > 2.19.1 >