From nobody Wed Jan 7 03:47:08 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 03346E784AC for ; Mon, 2 Oct 2023 13:49:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237529AbjJBNta (ORCPT ); Mon, 2 Oct 2023 09:49:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237514AbjJBNt1 (ORCPT ); Mon, 2 Oct 2023 09:49:27 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8896FD7 for ; Mon, 2 Oct 2023 06:49:24 -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 BD10B143D; Mon, 2 Oct 2023 06:50:02 -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 7384A3F762; Mon, 2 Oct 2023 06:49:23 -0700 (PDT) From: Robin Murphy To: joro@8bytes.org, will@kernel.org Cc: iommu@lists.linux.dev, jgg@nvidia.com, baolu.lu@linux.intel.com, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/7] iommu: Decouple iommu_present() from bus ops Date: Mon, 2 Oct 2023 14:49:10 +0100 Message-Id: X-Mailer: git-send-email 2.39.2.101.g768bb238c484.dirty In-Reply-To: References: 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" Much as I'd like to remove iommu_present(), the final remaining users are proving stubbornly difficult to clean up, so kick that can down the road and just rework it to preserve the current behaviour without depending on bus ops. Since commit 57365a04c921 ("iommu: Move bus setup to IOMMU device registration"), any registered IOMMU instance is already considered "present" for every entry in iommu_buses, so it's simply a case of validating the bus and checking we have at least once IOMMU. Signed-off-by: Robin Murphy Reviewed-by: Jason Gunthorpe --- v3: Tweak to use the ops-based check rather than group-based, to properly match the existing behaviour v4: Just look for IOMMU instances instead of managed devices --- drivers/iommu/iommu.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index f7793d1b5c3e..ef7feb0acc34 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1988,9 +1988,28 @@ int bus_iommu_probe(const struct bus_type *bus) return 0; } =20 +/** + * iommu_present() - make platform-specific assumptions about an IOMMU + * @bus: bus to check + * + * Do not use this function. You want device_iommu_mapped() instead. + * + * Return: true if some IOMMU is present and aware of devices on the given= bus; + * in general it may not be the only IOMMU, and it may not have anything t= o do + * with whatever device you are ultimately interested in. + */ bool iommu_present(const struct bus_type *bus) { - return bus->iommu_ops !=3D NULL; + bool ret =3D false; + + for (int i =3D 0; i < ARRAY_SIZE(iommu_buses); i++) { + if (iommu_buses[i] =3D=3D bus) { + spin_lock(&iommu_device_lock); + ret =3D !list_empty(&iommu_device_list); + spin_unlock(&iommu_device_lock); + } + } + return ret; } EXPORT_SYMBOL_GPL(iommu_present); =20 --=20 2.39.2.101.g768bb238c484.dirty