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 04B95C77B75 for ; Tue, 16 May 2023 01:50:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229753AbjEPBt7 (ORCPT ); Mon, 15 May 2023 21:49:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229553AbjEPBtz (ORCPT ); Mon, 15 May 2023 21:49:55 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42F511BD0; Mon, 15 May 2023 18:49:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1684201794; x=1715737794; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=yoBH6vhYXirTJn4ngLQetM+EEw/EqS96eNcX9cDbZ/o=; b=BR04lS4lP/ELMB8tQoS067kbCPNy39tya0lNKYcdtOBpA4roEG1G1Aeg YKmAxRUCqlkp2q2j0JyBzgTQiNJ1dEl9N6D9TmHAXQ5sarZxgrrMEnLe5 X4E0cHVpBEepw1U5mB/YC1Cwg0cVf6TfE3ec8l4qb0aLbPd/nB4ckSYZg qxq7/QjOBWaHSCrJh51nIX4JfsQuspI9Cbsea1wFqsZBobY8LThLt4ywt lRPUw2Etu408HkPLbjRrmiNcnWQrOJw8ScCkqiaf5h6Niu3ki4Z6HTqEA xjNug+iSQY8UxovqRQ/rDYrhsHiWnnovzBF6F0Qb+r/l6nu6ku6S+TstG g==; X-IronPort-AV: E=McAfee;i="6600,9927,10711"; a="340716246" X-IronPort-AV: E=Sophos;i="5.99,277,1677571200"; d="scan'208";a="340716246" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 May 2023 18:49:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10711"; a="790880836" X-IronPort-AV: E=Sophos;i="5.99,277,1677571200"; d="scan'208";a="790880836" Received: from allen-box.sh.intel.com (HELO [10.239.159.127]) ([10.239.159.127]) by FMSMGA003.fm.intel.com with ESMTP; 15 May 2023 18:49:48 -0700 Message-ID: <57101685-35c3-8a71-9a39-a6d9fd58414c@linux.intel.com> Date: Tue, 16 May 2023 09:49:13 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Cc: baolu.lu@linux.intel.com, "cohuck@redhat.com" , "eric.auger@redhat.com" , "nicolinc@nvidia.com" , "kvm@vger.kernel.org" , "mjrosato@linux.ibm.com" , "chao.p.peng@linux.intel.com" , "yi.y.sun@linux.intel.com" , "peterx@redhat.com" , "jasowang@redhat.com" , "shameerali.kolothum.thodi@huawei.com" , "lulu@redhat.com" , "suravee.suthikulpanit@amd.com" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "Duan, Zhenzhong" Subject: Re: [PATCH v3 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO Content-Language: en-US To: "Liu, Yi L" , "joro@8bytes.org" , "alex.williamson@redhat.com" , "jgg@nvidia.com" , "Tian, Kevin" , "robin.murphy@arm.com" References: <20230511143024.19542-1-yi.l.liu@intel.com> <20230511143024.19542-4-yi.l.liu@intel.com> <6ab2d63e-4dcc-6562-9698-d23300c7d1ae@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 5/15/23 2:14 PM, Liu, Yi L wrote: >> -----Original Message----- >> From: Baolu Lu >> Sent: Friday, May 12, 2023 1:39 PM >> To: Liu, Yi L;joro@8bytes.org;alex.williamson@redhat.com; >> jgg@nvidia.com; Tian, Kevin;robin.murphy@arm.com >> Cc:baolu.lu@linux.intel.com;cohuck@redhat.com;eric.auger@redhat.com; >> nicolinc@nvidia.com;kvm@vger.kernel.org;mjrosato@linux.ibm.com; >> chao.p.peng@linux.intel.com;yi.y.sun@linux.intel.com;peterx@redhat.com; >> jasowang@redhat.com;shameerali.kolothum.thodi@huawei.com;lulu@redhat.com; >> suravee.suthikulpanit@amd.com;iommu@lists.linux.dev;linux-kernel@vger.kernel.org; >> linux-kselftest@vger.kernel.org; Duan, Zhenzhong >> Subject: Re: [PATCH v3 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO >> >> On 5/11/23 10:30 PM, Yi Liu wrote: >>> Under nested IOMMU translation, userspace owns the stage-1 translation >>> table (e.g. the stage-1 page table of Intel VT-d or the context table >>> of ARM SMMUv3, and etc.). Stage-1 translation tables are vendor specific, >>> and needs to be compatiable with the underlying IOMMU hardware. Hence, >>> userspace should know the IOMMU hardware capability before creating and >>> configuring the stage-1 translation table to kernel. >>> >>> This adds IOMMU_DEVICE_GET_HW_INFO to query the IOMMU hardware >> information >>> for a given device. The returned data is vendor specific, userspace needs >>> to decode it with the structure mapped by the @out_data_type field. >>> >>> As only physical devices have IOMMU hardware, so this will return error >>> if the given device is not a physical device. >>> >>> Co-developed-by: Nicolin Chen >>> Signed-off-by: Nicolin Chen >>> Signed-off-by: Yi Liu >>> --- >>> drivers/iommu/iommufd/device.c | 72 +++++++++++++++++++++++++ >>> drivers/iommu/iommufd/iommufd_private.h | 1 + >>> drivers/iommu/iommufd/main.c | 3 ++ >>> include/uapi/linux/iommufd.h | 37 +++++++++++++ >>> 4 files changed, 113 insertions(+) >>> >>> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c >>> index 051bd8e99858..bc99d092de8f 100644 >>> --- a/drivers/iommu/iommufd/device.c >>> +++ b/drivers/iommu/iommufd/device.c >>> @@ -263,6 +263,78 @@ u32 iommufd_device_to_id(struct iommufd_device *idev) >>> } >>> EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, IOMMUFD); >>> >>> +static int iommufd_zero_fill_user(u64 ptr, int bytes) >>> +{ >>> + int index = 0; >>> + >>> + for (; index < bytes; index++) { >>> + if (put_user(0, (uint8_t __user *)u64_to_user_ptr(ptr + index))) >>> + return -EFAULT; >>> + } >>> + return 0; >>> +} >>> + >>> +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd) >>> +{ >>> + struct iommu_hw_info *cmd = ucmd->cmd; >>> + unsigned int length = 0, data_len; >>> + struct iommufd_device *idev; >>> + const struct iommu_ops *ops; >>> + void *data = NULL; >>> + int rc = 0; >>> + >>> + if (cmd->flags || cmd->__reserved || !cmd->data_len) >>> + return -EOPNOTSUPP; >>> + >>> + idev = iommufd_get_device(ucmd, cmd->dev_id); >>> + if (IS_ERR(idev)) >>> + return PTR_ERR(idev); >>> + >>> + ops = dev_iommu_ops(idev->dev); >>> + if (!ops->hw_info) >>> + goto done; >> If the iommu driver doesn't provide a hw_info callback, it still >> returns success? > Yes, as noted in the cover letter. It's for a remark from Jason. In such > case, the out_data_type is NULL, it means no specific data is filled > in the buffer pointed by cmd->data_ptr. > > - Let IOMMU_DEVICE_GET_HW_INFO succeed even the underlying iommu driver > does not have driver-specific data to report per below remark. > https://lore.kernel.org/kvm/ZAcwJSK%2F9UVI9LXu@nvidia.com/ Oh, I overlooked that. Thanks for the explanation. It's fair enough. Best regards, baolu