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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HhntSPDz; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68156606A339; Fri, 13 Nov 2026 13:11:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HhntSPDz Received: by smtp.kernel.org (Postfix) with ESMTPSA id 151971F000C4; Fri, 13 Nov 2026 13:11:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794575500; bh=UJJGqVjSBQwrXCt5oO1oVp31bm2wr0tRxTzs6y+s5eY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=HhntSPDz4hBtYpgjSDSSVhehC3ugFdt3d8uKPZhC9zPonuqtlUMxXtQgAXMu51sk+ c6XaBX4mO0q+UZo6swHPzJFo/cu1cNYby+GumuSJb/pVqWa6M9JH4jlEBT/Exzl7GL ilydPvL3dZGNK7a2kUtrXtR0vCyfsSfrp37MQPRL04JKFaIyA2wxO0cy5ZJPxSTlr0 v8iYKnqyavXMWdSClMn6YoV3XhTdrYpDGEwipYibWKjBD7yNxpuoauoWKAYDDvAG18 HB+RxkZpbQXP1mMGqKExpbXk0lrd8Hkf6F0/bRiOljbAPatD7c8Cs1nGKblzyWcaU1 yoMV4p8by0Ezg== Message-ID: <3e4b6491-2b58-4b9c-90ad-0912f47cb217@kernel.org> Date: Fri, 13 Nov 2026 14:11:30 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 4/5] iommu/of: Require reg for iommu-addresses To: Vikash Garodia , "Joerg Roedel (AMD)" , Vasant Hegde , Suravee Suthikulpanit , Will Deacon , Robin Murphy , David Woodhouse , Lu Baolu , Jean-Philippe Brucker , Rob Herring , Saravana Kannan , Tomasz Nowicki , Eric Auger , Bryan O'Donoghue , Joerg Roedel , Srinath Mannam , Oza Pawandeep , Lorenzo Pieralisi , Bjorn Helgaas , Alex Williamson Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, devicetree@vger.kernel.org, kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-media@vger.kernel.org, Vishnu Reddy References: <20261106-add_iommu_ranges-v7-0-5c0f72083e52@oss.qualcomm.com> <20261106-add_iommu_ranges-v7-4-5c0f72083e52@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 06/11/2026 18:14, Vikash Garodia wrote: > The "iommu-addresses" property describes an identity 1:1 mapping between > an IOVA range and the physical memory specified by "reg" in the same > reserved-memory node. Without "reg", there is no physical memory to map. This looks like ABI break. > > The DT schema now requires "reg" whenever "iommu-addresses" is present. > Align the kernel implementation with this requirement. > https://github.com/devicetree-org/dt-schema/pull/207 > > An identity mapping requires matching IOVA and "reg" ranges. Reject > mismatched ranges and report an error. > > Suggested-by: Rob Herring > Co-developed-by: Vishnu Reddy > Signed-off-by: Vishnu Reddy > Signed-off-by: Vikash Garodia > --- > drivers/iommu/of_iommu.c | 32 +++++++++++++++----------------- > 1 file changed, 15 insertions(+), 17 deletions(-) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index 6675fc900e6c2d55b34c61dc9effaeb48e24f18f..00b02c19f27e195fc36c4bc1d91253255147c9ab 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -174,19 +174,12 @@ iommu_resv_region_get_type(struct device *dev, > { > phys_addr_t end = start + length - 1; > > - /* > - * IOMMU regions without an associated physical region cannot be > - * mapped and are simply reservations. > - */ > - if (phys->start >= phys->end) > - return IOMMU_RESV_RESERVED; > - > /* may be IOMMU_RESV_DIRECT_RELAXABLE for certain cases */ > if (start == phys->start && end == phys->end) > return IOMMU_RESV_DIRECT; > > - dev_warn(dev, "treating non-direct mapping [%pr] -> [%pap-%pap] as reservation\n", phys, > - &start, &end); > + dev_err(dev, "non-direct mapping [%pr] -> [%pap-%pap] is not supported\n", phys, > + &start, &end); > return IOMMU_RESV_RESERVED; > } > > @@ -211,12 +204,14 @@ void of_iommu_get_resv_regions(struct device *dev, struct list_head *list) > struct resource phys; > int size; > > - memset(&phys, 0, sizeof(phys)); > + maps = of_get_property(it.node, "iommu-addresses", &size); > + if (!maps) > + continue; > > /* > - * 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. > + * "iommu-addresses" must be used in combination with a "reg" that provides > + * the physical address and size of this memory region, for an identity 1:1 > + * IOVA mapping to that physical memory. > */ > if (of_property_present(it.node, "reg")) { > err = of_address_to_resource(it.node, 0, &phys); > @@ -225,11 +220,11 @@ void of_iommu_get_resv_regions(struct device *dev, struct list_head *list) > it.node, err); > continue; > } > - } > - > - maps = of_get_property(it.node, "iommu-addresses", &size); > - if (!maps) I miss the point why you are moving this part. Irrespective to actual ABI break, why do you nee to check for iommu-addresses before? Best regards, Krzysztof