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 6D485C433F5 for ; Fri, 7 Oct 2022 13:47:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229751AbiJGNrd (ORCPT ); Fri, 7 Oct 2022 09:47:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbiJGNrc (ORCPT ); Fri, 7 Oct 2022 09:47:32 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F0CE2BBE28; Fri, 7 Oct 2022 06:47:30 -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 0407C106F; Fri, 7 Oct 2022 06:47:37 -0700 (PDT) Received: from [10.57.65.170] (unknown [10.57.65.170]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 355233F67D; Fri, 7 Oct 2022 06:47:27 -0700 (PDT) Message-ID: Date: Fri, 7 Oct 2022 14:47:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Thunderbird/102.3.1 Subject: Re: [PATCH v9 2/5] iommu: Implement of_iommu_get_resv_regions() Content-Language: en-GB To: Thierry Reding , Rob Herring , Joerg Roedel Cc: Will Deacon , Nicolin Chen , Krishna Reddy , Dmitry Osipenko , Alyssa Rosenzweig , Janne Grunau , Sameer Pujar , devicetree@vger.kernel.org, iommu@lists.linux-foundation.org, linux-tegra@vger.kernel.org, asahi@lists.linux.dev, Frank Rowand , Rob Herring References: <20220923123557.866972-1-thierry.reding@gmail.com> <20220923123557.866972-3-thierry.reding@gmail.com> From: Robin Murphy In-Reply-To: <20220923123557.866972-3-thierry.reding@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 2022-09-23 13:35, Thierry Reding wrote: > From: Thierry Reding > > This is an implementation that IOMMU drivers can use to obtain reserved > memory regions from a device tree node. It uses the reserved-memory DT > bindings to find the regions associated with a given device. If these > regions are marked accordingly, identity mappings will be created for > them in the IOMMU domain that the devices will be attached to. > > Cc: Frank Rowand > Cc: devicetree@vger.kernel.org > Reviewed-by: Rob Herring > Signed-off-by: Thierry Reding > --- > Changes in v9: > - address review comments by Robin Murphy: > - warn about non-direct mappings since they are not supported yet > - cleanup code to require less indentation > - narrow scope of variables > > Changes in v8: > - cleanup set-but-unused variables > > Changes in v6: > - remove reference to now unused dt-bindings/reserved-memory.h include > > Changes in v5: > - update for new "iommu-addresses" device tree bindings > > Changes in v4: > - fix build failure on !CONFIG_OF_ADDRESS > > Changes in v3: > - change "active" property to identity mapping flag that is part of the > memory region specifier (as defined by #memory-region-cells) to allow > per-reference flags to be used > > Changes in v2: > - use "active" property to determine whether direct mappings are needed > > drivers/iommu/of_iommu.c | 104 +++++++++++++++++++++++++++++++++++++++ > include/linux/of_iommu.h | 8 +++ > 2 files changed, 112 insertions(+) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index 5696314ae69e..0bf2b08bca0a 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -172,3 +173,106 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, > > return ops; > } > + > +static inline bool check_direct_mapping(struct device *dev, struct resource *phys, Where "phys" is the virtual address, right? :( > + phys_addr_t start, phys_addr_t end) > +{ > + if (start != phys->start || end != phys->end) { > + dev_warn(dev, "treating non-direct mapping [%pr] -> [%pap-%pap] as reservation\n", > + &phys, &start, &end); > + return false; > + } > + > + return true; > +} > + > +/** > + * of_iommu_get_resv_regions - reserved region driver helper for device tree > + * @dev: device for which to get reserved regions > + * @list: reserved region list > + * > + * IOMMU drivers can use this to implement their .get_resv_regions() callback > + * for memory regions attached to a device tree node. See the reserved-memory > + * device tree bindings on how to use these: > + * > + * Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > + */ > +void of_iommu_get_resv_regions(struct device *dev, struct list_head *list) > +{ > +#if IS_ENABLED(CONFIG_OF_ADDRESS) > + struct of_phandle_iterator it; > + int err; > + > + of_for_each_phandle(&it, err, dev->of_node, "memory-region", NULL, 0) { > + const __be32 *maps, *end; > + struct resource res; > + int size; > + > + memset(&res, 0, sizeof(res)); > + > + /* > + * The "reg" property is optional and can be omitted by reserved-memory regions > + * that represent reservations in the IOVA space, which are regions that should > + * not be mapped. > + */ > + if (of_find_property(it.node, "reg", NULL)) { > + err = of_address_to_resource(it.node, 0, &res); > + if (err < 0) { > + dev_err(dev, "failed to parse memory region %pOF: %d\n", > + it.node, err); > + continue; > + } > + } > + > + maps = of_get_property(it.node, "iommu-addresses", &size); > + if (!maps) > + continue; > + > + end = maps + size / sizeof(__be32); > + > + while (maps < end) { > + struct device_node *np; > + u32 phandle; > + int na, ns; > + > + phandle = be32_to_cpup(maps++); > + np = of_find_node_by_phandle(phandle); > + na = of_n_addr_cells(np); > + ns = of_n_size_cells(np); > + > + if (np == dev->of_node) { > + int prot = IOMMU_READ | IOMMU_WRITE; > + struct iommu_resv_region *region; > + enum iommu_resv_type type; > + phys_addr_t start; > + size_t length; > + > + start = of_translate_dma_address(np, maps); > + length = of_read_number(maps + na, ns); > + > + /* > + * IOMMU regions without an associated physical region cannot be > + * mapped and are simply reservations. > + */ > + if (res.end > res.start) { > + phys_addr_t end = start + length - 1; > + > + if (check_direct_mapping(dev, &res, start, end)) > + type = IOMMU_RESV_DIRECT_RELAXABLE; Again I really don't think we should assume relaxable by default. Looking at the shape of things now, it seems like check_direct_mappings() wants to subsume the check on res as well and grow in to a more general function for determining the iommu_resv_type. Then we've got a clear place to start special-casing things like simple-framebuffer that we do know a bit more about. Thanks, Robin. > + else > + type = IOMMU_RESV_RESERVED; > + } else { > + type = IOMMU_RESV_RESERVED; > + } > + > + region = iommu_alloc_resv_region(start, length, prot, type); > + if (region) > + list_add_tail(®ion->list, list); > + } > + > + maps += na + ns; > + } > + } > +#endif > +} > +EXPORT_SYMBOL(of_iommu_get_resv_regions); > diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h > index 55c1eb300a86..9a5e6b410dd2 100644 > --- a/include/linux/of_iommu.h > +++ b/include/linux/of_iommu.h > @@ -12,6 +12,9 @@ extern const struct iommu_ops *of_iommu_configure(struct device *dev, > struct device_node *master_np, > const u32 *id); > > +extern void of_iommu_get_resv_regions(struct device *dev, > + struct list_head *list); > + > #else > > static inline const struct iommu_ops *of_iommu_configure(struct device *dev, > @@ -21,6 +24,11 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev, > return NULL; > } > > +static inline void of_iommu_get_resv_regions(struct device *dev, > + struct list_head *list) > +{ > +} > + > #endif /* CONFIG_OF_IOMMU */ > > #endif /* __OF_IOMMU_H */