From nobody Fri May 8 06:53:57 2026 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 9F503C433EF for ; Mon, 9 May 2022 10:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233489AbiEIKUo (ORCPT ); Mon, 9 May 2022 06:20:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233445AbiEIKUd (ORCPT ); Mon, 9 May 2022 06:20:33 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 2C608174939; Mon, 9 May 2022 03:16:17 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4C0E61063; Mon, 9 May 2022 03:16:13 -0700 (PDT) Received: from e121345-lin.cambridge.arm.com (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 3D4073F66F; Mon, 9 May 2022 03:16:12 -0700 (PDT) From: Robin Murphy To: joro@8bytes.org, will@kernel.org, bhelgaas@google.com, robh@kernel.org Cc: iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] iommu/dma: Explicitly sort PCI DMA windows Date: Mon, 9 May 2022 11:16:08 +0100 Message-Id: <35661036a7e4160850895f9b37f35408b6a29f2f.1652091160.git.robin.murphy@arm.com> X-Mailer: git-send-email 2.35.3.dirty MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Originally, creating the dma_ranges resource list in pre-sorted fashion was the simplest and most efficient way to enforce the order required by iova_reserve_pci_windows(). However since then at least one PCI host driver is now re-sorting the list for its own probe-time processing, which doesn't seem entirely unreasonable, so that basic assumption no longer holds. Make iommu-dma robust and get the sort order it needs by explicitly sorting, which means we can also save the effort at creation time and just build the list in whatever natural order the DT had. Signed-off-by: Robin Murphy Reviewed-by: Rob Herring --- v2: Clean up now-unused local variable drivers/iommu/dma-iommu.c | 13 ++++++++++++- drivers/pci/of.c | 8 +------- 2 files changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 09f6e1c0f9c0..d05538af4fe9 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -414,6 +415,15 @@ static int cookie_init_hw_msi_region(struct iommu_dma_= cookie *cookie, return 0; } =20 +static int iommu_dma_ranges_sort(void *priv, const struct list_head *a, + const struct list_head *b) +{ + struct resource_entry *res_a =3D list_entry(a, typeof(*res_a), node); + struct resource_entry *res_b =3D list_entry(b, typeof(*res_b), node); + + return res_a->res->start > res_b->res->start; +} + static int iova_reserve_pci_windows(struct pci_dev *dev, struct iova_domain *iovad) { @@ -432,6 +442,7 @@ static int iova_reserve_pci_windows(struct pci_dev *dev, } =20 /* Get reserved DMA windows from host bridge */ + list_sort(NULL, &bridge->dma_ranges, iommu_dma_ranges_sort); resource_list_for_each_entry(window, &bridge->dma_ranges) { end =3D window->res->start - window->offset; resv_iova: @@ -440,7 +451,7 @@ static int iova_reserve_pci_windows(struct pci_dev *dev, hi =3D iova_pfn(iovad, end); reserve_iova(iovad, lo, hi); } else if (end < start) { - /* dma_ranges list should be sorted */ + /* DMA ranges should be non-overlapping */ dev_err(&dev->dev, "Failed to reserve IOVA [%pa-%pa]\n", &start, &end); diff --git a/drivers/pci/of.c b/drivers/pci/of.c index cb2e8351c2cc..8f0ebaf9ae85 100644 --- a/drivers/pci/of.c +++ b/drivers/pci/of.c @@ -369,7 +369,6 @@ static int devm_of_pci_get_host_bridge_resources(struct= device *dev, =20 dev_dbg(dev, "Parsing dma-ranges property...\n"); for_each_of_pci_range(&parser, &range) { - struct resource_entry *entry; /* * If we failed translation or got a zero-sized region * then skip this range @@ -393,12 +392,7 @@ static int devm_of_pci_get_host_bridge_resources(struc= t device *dev, goto failed; } =20 - /* Keep the resource list sorted */ - resource_list_for_each_entry(entry, ib_resources) - if (entry->res->start > res->start) - break; - - pci_add_resource_offset(&entry->node, res, + pci_add_resource_offset(ib_resources, res, res->start - range.pci_addr); } =20 --=20 2.35.3.dirty