From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A07CE3382FB; Mon, 16 Mar 2026 11:49:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773661748; cv=none; b=WSiJ5jQwC/Z0LziiZldvn9FZxqZmAYdLfaLJbgMmobKN30ij4thK+dvw+OGVCT1tBlfGpxoW3VkxoE6X4DlRI+qqx5ppryiRpR+nzMfAQUdUq/jxREeFxgn7s9sEXrPiRWxZ9jLOYJWmW2NAug8RgqNqyOjbObf/uZb8jT5jwSc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773661748; c=relaxed/simple; bh=yDwyMIe0jT0uj9BxWLio6iTlR/uGJGGXKfkNbelhLxY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ezcEvvJ6u79PHk93WpNdqkIRqQlCLvMSmrh5OS3LboTxd1RhS9k9QzCpanbPKPRsy053i4woSX5RAijD3OAF9PZrEbhLkDNUIWhb2dbicSz227JJ5R9+T5KUIFrg0TeoVSG82J0aMtLjOKX7p9bn+5LjbAs0VmDwz9Rjfn2X3m4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 DA0B01477; Mon, 16 Mar 2026 04:48:59 -0700 (PDT) Received: from [10.57.61.116] (unknown [10.57.61.116]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2A63B3F778; Mon, 16 Mar 2026 04:49:01 -0700 (PDT) Message-ID: Date: Mon, 16 Mar 2026 11:48:58 +0000 Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] of/iommu: support multiple iommu-map entries per input ID To: Vijayanand Jitta , Joerg Roedel , Will Deacon , Rob Herring , Saravana Kannan , Richard Zhu , Lucas Stach , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Manivannan Sadhasivam , Bjorn Helgaas , Frank Li , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Marc Zyngier , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Dmitry Baryshkov , Konrad Dybcio , Bjorn Andersson , Conor Dooley , Krzysztof Kozlowski , Prakash Gupta , Vikash Garodia Cc: linux-arm-msm@vger.kernel.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, xen-devel@lists.xenproject.org References: <20260315-iommu_multi_map-v2-1-51b98cb79331@oss.qualcomm.com> From: Robin Murphy Content-Language: en-GB In-Reply-To: <20260315-iommu_multi_map-v2-1-51b98cb79331@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026-03-15 5:07 pm, Vijayanand Jitta wrote: > When multiple mappings are present for an input ID, linux matches > just the first one. There is a usecase [1] where all the mappings > are to be maintained in parallel for an iommu-map entry of a same > input id. > > Add a next_offset iterator parameter to of_map_iommu_id() and > refactor of_map_id() internals into a static helper to carry it. > Update of_iommu_configure_dev_id() to loop over all matching > entries to support this case. All other callers pass NULL and > are unaffected. > > [1] https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@quicinc.com/ That series doesn't even reference "iommu-map" though? Once again, NAK to this - the purpose of "iommu-map"/"msi-map" is to describe a translation from one hardware ID space to another, where a one-to-many mapping of IDs to a single target would never make sense. While it is in principle possible for a single device to map to multiple different *targets*, that is ambiguous as to what it means - is it giving the OS a choice to use whichever one it prefers, or implying they must all be configured identically at all times? - so depending on how you prefer to look at it, we either do not support that, or we have chosen the first option. > Signed-off-by: Vijayanand Jitta > --- > On Qualcomm kaanapali, the VPU hardware has multiple internal blocks > that generate different stream IDs for the same input ID. The device > tree encodes them as separate iommu-map entries sharing the same input > ID: And all that means is that your invented notion of "input IDs" is clearly wrong. Please stop this abuse of common bindings and just come up with a proper way to describe your hardware appropriately for what it actually is and does. Thanks, Robin. > iommu-map = <0x100 &apps_smmu 0x1940 0x1>, > <0x100 &apps_smmu 0x1a20 0x1>, ... > > This requires multiple iommu-map entries per device. > of_iommu_configure_dev_id() currently stops at the first match, > so only one stream ID gets registered with the IOMMU. > > The v1 series [1] addressed this with a callback threaded through > of_map_id(). > > This patch uses a next_offset iterator on of_map_iommu_id() instead, > keeping of_map_id() unchanged, and updates of_iommu_configure_dev_id() > to loop over all matching entries. > > This patch also depends on iommu-cells series [4]. > > Changes since v1: > - Split patches 2/7 [2] and 3/7 [3] out into this standalone series. > - Dropped the callback (of_map_id_cb / of_map_id_arg) entirely. > - Replaced with a next_offset iterator on of_map_iommu_id() > only; of_map_id() public API is unchanged. > - of_iommu_configure_dev_id() now loops explicitly; no > bus-type heuristic (dev_is_platform()) needed. > > [1] https://lore.kernel.org/all/20260126-kaanapali-iris-v1-0-e2646246bfc1@oss.qualcomm.com/ > [2] https://lore.kernel.org/all/20260126-kaanapali-iris-v1-2-e2646246bfc1@oss.qualcomm.com/ > [3] https://lore.kernel.org/all/20260126-kaanapali-iris-v1-3-e2646246bfc1@oss.qualcomm.com/ > [4] https://lore.kernel.org/all/ce25b963-0e8e-4411-a406-7b466eadb1f9@oss.qualcomm.com/ > > Signed-off-by: Vijayanand Jitta > --- > drivers/iommu/of_iommu.c | 20 +++++++---- > drivers/of/base.c | 65 ++++++++++++++++++++++++++++++----- > drivers/pci/controller/dwc/pci-imx6.c | 2 +- > drivers/pci/controller/pcie-apple.c | 2 +- > drivers/xen/grant-dma-ops.c | 2 +- > include/linux/of.h | 4 +-- > 6 files changed, 75 insertions(+), 20 deletions(-) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index a18bb60f6f3d..947eedd9a88b 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -46,14 +46,22 @@ static int of_iommu_configure_dev_id(struct device_node *master_np, > const u32 *id) > { > struct of_phandle_args iommu_spec = {}; > - int err; > + int offset = 0, err; > + bool found = false; > > - err = of_map_iommu_id(master_np, *id, &iommu_spec); > - if (err) > - return err; > + while (!(err = of_map_iommu_id(master_np, *id, &iommu_spec, &offset))) { > + err = of_iommu_xlate(dev, &iommu_spec); > + of_node_put(iommu_spec.np); > + iommu_spec.np = NULL; > + if (err) > + return err; > + found = true; > + } > + > + /* -ENODEV means all entries exhausted; success if at least one was processed */ > + if (err == -ENODEV && found) > + return 0; > > - err = of_iommu_xlate(dev, &iommu_spec); > - of_node_put(iommu_spec.np); > return err; > } > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 9c44eb6d445d..71175e670757 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -2146,13 +2146,13 @@ static bool of_check_bad_map(const __be32 *map, int len) > * > * Return: 0 on success or a standard error code on failure. > */ > -int of_map_id(const struct device_node *np, u32 id, > - const char *map_name, const char *cells_name, > - const char *map_mask_name, > - struct of_phandle_args *arg) > +static int of_map_id_next(const struct device_node *np, u32 id, > + const char *map_name, const char *cells_name, > + const char *map_mask_name, > + struct of_phandle_args *arg, int *next_offset) > { > u32 map_mask, masked_id; > - int map_bytes, map_len, offset = 0; > + int map_bytes, map_len, offset = next_offset ? *next_offset : 0; > bool bad_map = false; > const __be32 *map = NULL; > > @@ -2161,7 +2161,7 @@ int of_map_id(const struct device_node *np, u32 id, > > map = of_get_property(np, map_name, &map_bytes); > if (!map) { > - if (arg->np) > + if (arg->np || next_offset) > return -ENODEV; > /* Otherwise, no map implies no translation */ > arg->args[0] = id; > @@ -2262,9 +2262,16 @@ int of_map_id(const struct device_node *np, u32 id, > pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n", > np, map_name, map_mask, id_base, be32_to_cpup(out_base), > id_len, id, id_off + be32_to_cpup(out_base)); > + > + if (next_offset) > + *next_offset = offset; /* caller resumes from here */ > return 0; > } > > + /* no (more) matches found in the map */ > + if (next_offset) > + return -ENODEV; > + > pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name, > id, arg->np); > > @@ -2276,6 +2283,38 @@ int of_map_id(const struct device_node *np, u32 id, > pr_err("%pOF: Error: Bad %s length: %d\n", np, map_name, map_bytes); > return -EINVAL; > } > + > +/** > + * of_map_id - Translate an ID through a downstream mapping. > + * @np: root complex device node. > + * @id: device ID to map. > + * @map_name: property name of the map to use. > + * @cells_name: property name of target specifier cells. > + * @map_mask_name: optional property name of the mask to use. > + * @arg: pointer to a &struct of_phandle_args. On input, @arg->np may be > + * set to a target device node to match, or NULL to match any. On > + * success, @arg->np will be set to the matched target node (with a > + * reference held), @arg->args_count will be set to the number of > + * output specifier cells as defined by @cells_name in the target node, > + * and @arg->args[0..args_count-1] will contain the translated output > + * specifier values. > + * > + * Given a device ID, look up the appropriate implementation-defined > + * platform ID and/or the target device which receives transactions on that > + * ID, as per the "iommu-map" and "msi-map" bindings. If @arg->np points to > + * a non-NULL device node, only entries targeting that node will be matched; > + * if it is NULL, it will receive the device node of the first matching > + * target phandle, with a reference held. > + * > + * Return: 0 on success or a standard error code on failure. > + */ > +int of_map_id(const struct device_node *np, u32 id, > + const char *map_name, const char *cells_name, > + const char *map_mask_name, > + struct of_phandle_args *arg) > +{ > + return of_map_id_next(np, id, map_name, cells_name, map_mask_name, arg, NULL); > +} > EXPORT_SYMBOL_GPL(of_map_id); > > /** > @@ -2285,15 +2324,23 @@ EXPORT_SYMBOL_GPL(of_map_id); > * @arg: pointer to a &struct of_phandle_args for the result. On success, > * @arg->np holds a reference to the target node that the caller must > * release with of_node_put(). > + * @next_offset: if non-NULL, on success it is set to the map offset just > + * past the matched entry. Pass this value back on the next call to > + * resume scanning from where the previous call left off, allowing all > + * matching entries for the same @id to be iterated. Pass NULL (or a > + * pointer to 0) to find only the first match. > * > - * Convenience wrapper around of_map_id() using "iommu-map" and "iommu-map-mask". > + * Wrapper around the internal iommu-map scanner using "iommu-map" and > + * "iommu-map-mask". When @next_offset is non-NULL, returns -ENODEV once > + * all matching entries have been exhausted. > * > * Return: 0 on success or a standard error code on failure. > */ > int of_map_iommu_id(const struct device_node *np, u32 id, > - struct of_phandle_args *arg) > + struct of_phandle_args *arg, int *next_offset) > { > - return of_map_id(np, id, "iommu-map", "#iommu-cells", "iommu-map-mask", arg); > + return of_map_id_next(np, id, "iommu-map", "#iommu-cells", > + "iommu-map-mask", arg, next_offset); > } > EXPORT_SYMBOL_GPL(of_map_iommu_id); > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > index 5f8a11774eb5..0d7f5e6d037a 100644 > --- a/drivers/pci/controller/dwc/pci-imx6.c > +++ b/drivers/pci/controller/dwc/pci-imx6.c > @@ -1146,7 +1146,7 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid) > u32 sid = 0; > > target = NULL; > - err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec); > + err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec, NULL); > if (!err_i) { > target = iommu_spec.np; > sid_i = iommu_spec.args[0]; > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c > index 2e86f8fd300b..c780e3f9d14d 100644 > --- a/drivers/pci/controller/pcie-apple.c > +++ b/drivers/pci/controller/pcie-apple.c > @@ -765,7 +765,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d > dev_dbg(&pdev->dev, "added to bus %s, index %d\n", > pci_name(pdev->bus->self), port->idx); > > - err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec); > + err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec, NULL); > if (err) > return err; > > diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c > index 36547d7cf1d6..062beb5825f5 100644 > --- a/drivers/xen/grant-dma-ops.c > +++ b/drivers/xen/grant-dma-ops.c > @@ -325,7 +325,7 @@ static int xen_dt_grant_init_backend_domid(struct device *dev, > struct pci_dev *pdev = to_pci_dev(dev); > u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn); > > - if (of_map_iommu_id(np, rid, &iommu_spec)) { > + if (of_map_iommu_id(np, rid, &iommu_spec, NULL)) { > dev_dbg(dev, "Cannot translate ID\n"); > return -ESRCH; > } > diff --git a/include/linux/of.h b/include/linux/of.h > index 953f2dbe0e86..990849f00e74 100644 > --- a/include/linux/of.h > +++ b/include/linux/of.h > @@ -467,7 +467,7 @@ int of_map_id(const struct device_node *np, u32 id, > struct of_phandle_args *arg); > > int of_map_iommu_id(const struct device_node *np, u32 id, > - struct of_phandle_args *arg); > + struct of_phandle_args *arg, int *next_offset); > > int of_map_msi_id(const struct device_node *np, u32 id, > struct of_phandle_args *arg); > @@ -943,7 +943,7 @@ static inline int of_map_id(const struct device_node *np, u32 id, > } > > static inline int of_map_iommu_id(const struct device_node *np, u32 id, > - struct of_phandle_args *arg) > + struct of_phandle_args *arg, int *next_offset) > { > return -EINVAL; > } > > --- > base-commit: 9e94742cffb7541f55fa904a40c1ca9d836d303d > change-id: 20260315-iommu_multi_map-8c9b78490ace > > Best regards,