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 EFD61C433EF for ; Thu, 2 Jun 2022 19:24:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238624AbiFBTYu (ORCPT ); Thu, 2 Jun 2022 15:24:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59028 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238540AbiFBTY0 (ORCPT ); Thu, 2 Jun 2022 15:24:26 -0400 Received: from mail-ej1-x629.google.com (mail-ej1-x629.google.com [IPv6:2a00:1450:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E74BA260F for ; Thu, 2 Jun 2022 12:24:24 -0700 (PDT) Received: by mail-ej1-x629.google.com with SMTP id rq11so11849481ejc.4 for ; Thu, 02 Jun 2022 12:24:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=iNk74UaWLtQZL938Xxs3lBfmlvnA9FseeUHkafxECOY=; b=l5kSUmTyGQGXi74E515dldlWlFe3o08m4WJUZfONrAYROcSF48RNd1TEGdK3LNFW+s tHjQHCQNYLmJh9wphr3xZq+NVXxnGx3cH+ocoirkpGeSZ869Kup4B5xOfIsyusPe34JW fimV2t9ST7TGBac/fuJaEnuwygaZgZ26gqFiCY1muNWsRbEzGytMUMQZC+PpYHUU7H29 PVza1L+tH2IrywKG2WMwfvahBQ9yUpDBlpQqq+UjuysWSRqg/fQRnKtJgG0s+bfA05tE a1K1tERwgCp1gamFt3ZSwmgs8FxhO+ttN+3bbIuzaXgPzMAYhqlnluJoFMc+67kQwS3r 9Ecg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=iNk74UaWLtQZL938Xxs3lBfmlvnA9FseeUHkafxECOY=; b=vCA+zkOxYkhxrVteqxHhXRxtCsZNQpNxWFwBeUj+rnSulJVmnfxBgGOu6WZ8Xy37f+ XE9H2BGyf63yHOR/JImDMsYUSJ/5hpmuZWXw9FlG5YgzydhZVHuzh7oJMi8W9rSUY1TM JiXH4ut8bojq4W999n/9MxPpN7shsEgjLv6iRHEpViI5oTlAGPY1GdcreVGnZdY3VsTk obApEeJH32Cfh6uI0cAz6E9SzKVz5pfaeq5MP5wuBRu1tWE6tiUX2ZolmVQoojEej+44 9UffaN8WGPkZhlGY8qatnJ5g7W5NKph6t+5/gKMcoMGHVjrRhMMvFKRv8+4CxzTvmre7 27dA== X-Gm-Message-State: AOAM532moIy4uX6eiURu1w45GZlD0BItznQpLcp8vj+12LM1zr/MXkNK I3Mm1USNTGS6iF7NL43BBw0= X-Google-Smtp-Source: ABdhPJwzZQbzIbCIFf3Pkn1ya1TGT8EEvSTk8i6RqQF4X2KAXdSL8hILlCy1w1gJmVJ7oRgwQh7H8w== X-Received: by 2002:a17:906:d1cc:b0:709:567f:3506 with SMTP id bs12-20020a170906d1cc00b00709567f3506mr5538761ejb.363.1654197863445; Thu, 02 Jun 2022 12:24:23 -0700 (PDT) Received: from otyshchenko.router ([212.22.223.21]) by smtp.gmail.com with ESMTPSA id eg13-20020a056402288d00b0042dce73168csm2938301edb.13.2022.06.02.12.24.22 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 02 Jun 2022 12:24:23 -0700 (PDT) From: Oleksandr Tyshchenko To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Oleksandr Tyshchenko , Stefano Stabellini , Boris Ostrovsky , Juergen Gross , Julien Grall , "Michael S. Tsirkin" , Christoph Hellwig Subject: [PATCH V4 6/8] xen/grant-dma-iommu: Introduce stub IOMMU driver Date: Thu, 2 Jun 2022 22:23:51 +0300 Message-Id: <1654197833-25362-7-git-send-email-olekstysh@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1654197833-25362-1-git-send-email-olekstysh@gmail.com> References: <1654197833-25362-1-git-send-email-olekstysh@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleksandr Tyshchenko In order to reuse generic IOMMU device tree bindings by Xen grant DMA-mapping layer we need to add this stub driver from a fw_devlink perspective (grant-dma-ops cannot be converted into the proper IOMMU driver). Otherwise, just reusing IOMMU bindings (without having a corresponding driver) leads to the deferred probe timeout afterwards, because the IOMMU device never becomes available. This stub driver does nothing except registering empty iommu_ops, the upper layer "of_iommu" will treat this as NO_IOMMU condition and won't return -EPROBE_DEFER. As this driver is quite different from the most hardware IOMMU implementations and only needed in Xen guests, place it in drivers/xen directory. The subsequent commit will make use of it. Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini --- According to the discussion at: https://lore.kernel.org/xen-devel/c0f78aab-e723-fe00-a310-9fe52ec75e48@gmail.com/ Change V2 -> V3: - new patch Changes V3 -> V4: - add Stefano's R-b --- drivers/xen/Kconfig | 4 +++ drivers/xen/Makefile | 1 + drivers/xen/grant-dma-iommu.c | 78 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 83 insertions(+) create mode 100644 drivers/xen/grant-dma-iommu.c diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index a7bd8ce..35d20d9 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -335,6 +335,10 @@ config XEN_UNPOPULATED_ALLOC having to balloon out RAM regions in order to obtain physical memory space to create such mappings. +config XEN_GRANT_DMA_IOMMU + bool + select IOMMU_API + config XEN_GRANT_DMA_OPS bool select DMA_OPS diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 1a23cb0..c0503f1 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -40,3 +40,4 @@ xen-privcmd-y := privcmd.o privcmd-buf.o obj-$(CONFIG_XEN_FRONT_PGDIR_SHBUF) += xen-front-pgdir-shbuf.o obj-$(CONFIG_XEN_UNPOPULATED_ALLOC) += unpopulated-alloc.o obj-$(CONFIG_XEN_GRANT_DMA_OPS) += grant-dma-ops.o +obj-$(CONFIG_XEN_GRANT_DMA_IOMMU) += grant-dma-iommu.o diff --git a/drivers/xen/grant-dma-iommu.c b/drivers/xen/grant-dma-iommu.c new file mode 100644 index 00000000..16b8bc0 --- /dev/null +++ b/drivers/xen/grant-dma-iommu.c @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Stub IOMMU driver which does nothing. + * The main purpose of it being present is to reuse generic IOMMU device tree + * bindings by Xen grant DMA-mapping layer. + * + * Copyright (C) 2022 EPAM Systems Inc. + */ + +#include +#include +#include + +struct grant_dma_iommu_device { + struct device *dev; + struct iommu_device iommu; +}; + +/* Nothing is really needed here */ +static const struct iommu_ops grant_dma_iommu_ops; + +static const struct of_device_id grant_dma_iommu_of_match[] = { + { .compatible = "xen,grant-dma" }, + { }, +}; + +static int grant_dma_iommu_probe(struct platform_device *pdev) +{ + struct grant_dma_iommu_device *mmu; + int ret; + + mmu = devm_kzalloc(&pdev->dev, sizeof(*mmu), GFP_KERNEL); + if (!mmu) + return -ENOMEM; + + mmu->dev = &pdev->dev; + + ret = iommu_device_register(&mmu->iommu, &grant_dma_iommu_ops, &pdev->dev); + if (ret) + return ret; + + platform_set_drvdata(pdev, mmu); + + return 0; +} + +static int grant_dma_iommu_remove(struct platform_device *pdev) +{ + struct grant_dma_iommu_device *mmu = platform_get_drvdata(pdev); + + platform_set_drvdata(pdev, NULL); + iommu_device_unregister(&mmu->iommu); + + return 0; +} + +static struct platform_driver grant_dma_iommu_driver = { + .driver = { + .name = "grant-dma-iommu", + .of_match_table = grant_dma_iommu_of_match, + }, + .probe = grant_dma_iommu_probe, + .remove = grant_dma_iommu_remove, +}; + +static int __init grant_dma_iommu_init(void) +{ + struct device_node *iommu_np; + + iommu_np = of_find_matching_node(NULL, grant_dma_iommu_of_match); + if (!iommu_np) + return 0; + + of_node_put(iommu_np); + + return platform_driver_register(&grant_dma_iommu_driver); +} +subsys_initcall(grant_dma_iommu_init); -- 2.7.4