From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 25D504ADDBE for ; Mon, 11 May 2026 18:41:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778524882; cv=none; b=rwObdhlAaTyCi+q55rX79vJRRYkkDEi4kqDg6UQ7fPpPngoxiN7viCHaKWpi0Iqh2j/f4JZ+61Tt9IYRUz0EZk1uRrF3epnW3hrqq38eHvUoH0MGl1uKDFG1drWMWS6voG6e36DTZor25Wufan6D+vsawMA8x5AcuuZ/TWAFQ7k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778524882; c=relaxed/simple; bh=DaspiKIfSFio4VTISQhAiLDWpdnRJjb51za7mPSAX+Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bizY+MEfN5wY/cBbi91nOiTDZlsAA0qwtw5zjhRvh6XUwl+cb8IaX7f7hyyzXO8OGMZmhg9LHsiIFD1nJ7bGuvvuaoY/4y9gaJZF7pL+nrj8OKv6+qrL5903MWxGg7RAV1VI7RsWzVkn//pWmNF8IaGvo7A3e3NVoR73odqiYtA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=ALwXEGZ2; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="ALwXEGZ2" Received: from administrator-PowerEdge-R660.corp.microsoft.com (unknown [131.107.147.7]) by linux.microsoft.com (Postfix) with ESMTPSA id 6193920B716C; Mon, 11 May 2026 11:41:18 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 6193920B716C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1778524878; bh=o/Uk4IOdsYKAtmsHn82zexbucnOfgG88cc8Diqnjjsw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ALwXEGZ2voqH2EtrmyQZPKyDHKcMEIuCC7+rURH8BJAatHjOuF7gCexQyhj1b2SUY CKjsPivTR39hm7IGpRr+ZgosV2dx0pjylLoTxxZlYJ+E469TE/szevyU7YU1BbYYyy hahF6qybQ0HOJuiVOO3DV/YbvxJOv1TQdshwrRIQ= From: Jacob Pan To: linux-kernel@vger.kernel.org, "iommu@lists.linux.dev" , Jason Gunthorpe , Alex Williamson , Joerg Roedel , Mostafa Saleh , David Matlack , Robin Murphy , Nicolin Chen , "Tian, Kevin" , Yi Liu Cc: Saurabh Sengar , skhawaja@google.com, pasha.tatashin@soleen.com, Will Deacon , Jacob Pan , Baolu Lu Subject: [PATCH v5 4/9] iommufd: Allow binding to a noiommu device Date: Mon, 11 May 2026 11:41:09 -0700 Message-ID: <20260511184116.3687392-5-jacob.pan@linux.microsoft.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260511184116.3687392-1-jacob.pan@linux.microsoft.com> References: <20260511184116.3687392-1-jacob.pan@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jason Gunthorpe Allow iommufd to bind devices without an IOMMU (noiommu mode) by creating a dummy IOMMU group for such devices and skipping hwpt operations. This enables noiommu devices to operate through the same iommufd API as IOMMU- capable devices. Signed-off-by: Jason Gunthorpe Signed-off-by: Jacob Pan --- v5: - simplify logic and rename iommufd_device_is_noiommu (Kevin, Yi) - use a helper iommufd_bind_noiommu instead of open coding (Kevin) - move IOMMU cap check under iommufd_bind_iommu() (Yi) - reword comments for partial init (Yi) - misc minor clean up v4: - Update the description of the module parameter (Alex) v3: - Consolidate into fewer patches --- drivers/iommu/iommufd/device.c | 148 ++++++++++++++++++++++++--------- 1 file changed, 109 insertions(+), 39 deletions(-) diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index d03076fcf3c2..4d75720432cc 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -23,6 +23,16 @@ struct iommufd_attach { struct xarray device_array; }; +/* + * A noiommu device has no IOMMU driver attached regardless of whether it + * enters via the cdev path (no iommu_group) or the group path (fake + * noiommu iommu_group). In both cases dev->iommu is NULL. + */ +static bool iommufd_device_is_noiommu(struct iommufd_device *idev) +{ + return IS_ENABLED(CONFIG_IOMMUFD_NOIOMMU) && !idev->dev->iommu; +} + static void iommufd_group_release(struct kref *kref) { struct iommufd_group *igroup = @@ -30,9 +40,11 @@ static void iommufd_group_release(struct kref *kref) WARN_ON(!xa_empty(&igroup->pasid_attach)); - xa_cmpxchg(&igroup->ictx->groups, iommu_group_id(igroup->group), igroup, - NULL, GFP_KERNEL); - iommu_group_put(igroup->group); + if (igroup->group) { + xa_cmpxchg(&igroup->ictx->groups, iommu_group_id(igroup->group), + igroup, NULL, GFP_KERNEL); + iommu_group_put(igroup->group); + } mutex_destroy(&igroup->lock); kfree(igroup); } @@ -204,32 +216,19 @@ void iommufd_device_destroy(struct iommufd_object *obj) struct iommufd_device *idev = container_of(obj, struct iommufd_device, obj); - iommu_device_release_dma_owner(idev->dev); + if (!idev->igroup) + return; + if (!iommufd_device_is_noiommu(idev)) + iommu_device_release_dma_owner(idev->dev); iommufd_put_group(idev->igroup); if (!iommufd_selftest_is_mock_dev(idev->dev)) iommufd_ctx_put(idev->ictx); } -/** - * iommufd_device_bind - Bind a physical device to an iommu fd - * @ictx: iommufd file descriptor - * @dev: Pointer to a physical device struct - * @id: Output ID number to return to userspace for this device - * - * A successful bind establishes an ownership over the device and returns - * struct iommufd_device pointer, otherwise returns error pointer. - * - * A driver using this API must set driver_managed_dma and must not touch - * the device until this routine succeeds and establishes ownership. - * - * Binding a PCI device places the entire RID under iommufd control. - * - * The caller must undo this with iommufd_device_unbind() - */ -struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, - struct device *dev, u32 *id) +static int iommufd_bind_iommu(struct iommufd_device *idev) { - struct iommufd_device *idev; + struct iommufd_ctx *ictx = idev->ictx; + struct device *dev = idev->dev; struct iommufd_group *igroup; int rc; @@ -238,11 +237,11 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, * to restore cache coherency. */ if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY)) - return ERR_PTR(-EINVAL); + return -EINVAL; igroup = iommufd_get_group(ictx, dev); if (IS_ERR(igroup)) - return ERR_CAST(igroup); + return PTR_ERR(igroup); /* * For historical compat with VFIO the insecure interrupt path is @@ -268,21 +267,80 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, if (rc) goto out_group_put; + /* igroup refcount moves into iommufd_device */ + idev->igroup = igroup; + idev->enforce_cache_coherency = + device_iommu_capable(dev, IOMMU_CAP_ENFORCE_CACHE_COHERENCY); + return 0; + +out_group_put: + iommufd_put_group(igroup); + return rc; +} + +/* + * Noiommu devices have no real IOMMU group. Create a dummy igroup so that + * internal code paths that expect idev->igroup to be present still work. + * A NULL igroup->group distinguishes this from a real IOMMU-backed group. + */ +static int iommufd_bind_noiommu(struct iommufd_device *idev) +{ + struct iommufd_group *igroup; + + igroup = iommufd_alloc_group(idev->ictx, NULL); + if (IS_ERR(igroup)) + return PTR_ERR(igroup); + idev->igroup = igroup; + return 0; +} + +/** + * iommufd_device_bind - Bind a physical device to an iommu fd + * @ictx: iommufd file descriptor + * @dev: Pointer to a physical device struct + * @id: Output ID number to return to userspace for this device + * + * A successful bind establishes an ownership over the device and returns + * struct iommufd_device pointer, otherwise returns error pointer. + * + * A driver using this API must set driver_managed_dma and must not touch + * the device until this routine succeeds and establishes ownership. + * + * Binding a PCI device places the entire RID under iommufd control. + * + * The caller must undo this with iommufd_device_unbind() + */ +struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, + struct device *dev, u32 *id) +{ + struct iommufd_device *idev; + int rc; + idev = iommufd_object_alloc(ictx, idev, IOMMUFD_OBJ_DEVICE); - if (IS_ERR(idev)) { - rc = PTR_ERR(idev); - goto out_release_owner; - } + if (IS_ERR(idev)) + return idev; + idev->ictx = ictx; + idev->dev = dev; + + if (!iommufd_device_is_noiommu(idev)) { + rc = iommufd_bind_iommu(idev); + if (rc) + goto err_out; + } else { + rc = iommufd_bind_noiommu(idev); + if (rc) + goto err_out; + } + + /* + * Take a ctx reference after bind succeeds. This must happen here + * so that iommufd_device_destroy() can handle partial initialization + */ if (!iommufd_selftest_is_mock_dev(dev)) iommufd_ctx_get(ictx); - idev->dev = dev; - idev->enforce_cache_coherency = - device_iommu_capable(dev, IOMMU_CAP_ENFORCE_CACHE_COHERENCY); /* The calling driver is a user until iommufd_device_unbind() */ refcount_inc(&idev->obj.users); - /* igroup refcount moves into iommufd_device */ - idev->igroup = igroup; /* * If the caller fails after this success it must call @@ -294,11 +352,14 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx, *id = idev->obj.id; return idev; -out_release_owner: - iommu_device_release_dma_owner(dev); -out_group_put: - iommufd_put_group(igroup); +err_out: + /* + * iommufd_device_destroy() handles partially initialized idev, + * so iommufd_object_abort_and_destroy() is safe to call here. + */ + iommufd_object_abort_and_destroy(ictx, &idev->obj); return ERR_PTR(rc); + } EXPORT_SYMBOL_NS_GPL(iommufd_device_bind, "IOMMUFD"); @@ -512,6 +573,9 @@ static int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt, struct iommufd_attach_handle *handle; int rc; + if (iommufd_device_is_noiommu(idev)) + return 0; + if (!iommufd_hwpt_compatible_device(hwpt, idev)) return -EINVAL; @@ -559,6 +623,9 @@ static void iommufd_hwpt_detach_device(struct iommufd_hw_pagetable *hwpt, { struct iommufd_attach_handle *handle; + if (iommufd_device_is_noiommu(idev)) + return; + handle = iommufd_device_get_attach_handle(idev, pasid); if (pasid == IOMMU_NO_PASID) iommu_detach_group_handle(hwpt->domain, idev->igroup->group); @@ -577,6 +644,9 @@ static int iommufd_hwpt_replace_device(struct iommufd_device *idev, struct iommufd_attach_handle *handle, *old_handle; int rc; + if (iommufd_device_is_noiommu(idev)) + return 0; + if (!iommufd_hwpt_compatible_device(hwpt, idev)) return -EINVAL; @@ -652,7 +722,7 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt, goto err_release_devid; } - if (attach_resv) { + if (attach_resv && !iommufd_device_is_noiommu(idev)) { rc = iommufd_device_attach_reserved_iova(idev, hwpt_paging); if (rc) goto err_release_devid; -- 2.43.0