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 61947C43334 for ; Tue, 21 Jun 2022 06:15:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345829AbiFUGPV (ORCPT ); Tue, 21 Jun 2022 02:15:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343662AbiFUGPR (ORCPT ); Tue, 21 Jun 2022 02:15:17 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4A5415FFE; Mon, 20 Jun 2022 23:15:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655792115; x=1687328115; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=zNh6pUo3+c2mfFlvlWk9GP/Xel6H0s4DqcuTRAGy/N8=; b=JFWYIp4+SMfB4wyhLPdbhb7dybXrokpA1h6y5WTNP+ybZZxVGiGACKqk Eo4yiPDPHX3HVXTQg01hLbrhQJv+DD1E22HKvyukfUlbOTDErz3NxWHWU VlnvuWTbJd9wgsdEJmA6jP48pYPr1RjBr8ybfN6X5A99dZf8QxbHsF4kF i3sTv/rtTaHPPMCcwBDp+0x3lP9IqVf8VksMXE4VirHOnUpGA2sIxFXHN dx8ceoC5xZi97mu9Jn1+AXqpeuOWtIpl4bMRDozPcnfYMKHHC//7XrThu ahYia1bHbQZ0U3jOTaWi53zwGJwD5iqYiN4CXLKcu66nQlTmWRJ8t2A5d Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10384"; a="305475553" X-IronPort-AV: E=Sophos;i="5.92,209,1650956400"; d="scan'208";a="305475553" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2022 23:15:15 -0700 X-IronPort-AV: E=Sophos;i="5.92,209,1650956400"; d="scan'208";a="833426034" Received: from zequnyu-mobl1.ccr.corp.intel.com (HELO [10.255.31.162]) ([10.255.31.162]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2022 23:15:13 -0700 Message-ID: <88295461-7cba-7c30-6b9e-63ee77e90295@linux.intel.com> Date: Tue, 21 Jun 2022 14:15:11 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Cc: baolu.lu@linux.intel.com, "Qiang, Chenyi" , "Liu, Yi L" , "Pan, Jacob jun" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH 1/1] iommu/vt-d: Fix RID2PASID setup failure Content-Language: en-US To: "Tian, Kevin" , Joerg Roedel , "Raj, Ashok" References: <20220620081729.4610-1-baolu.lu@linux.intel.com> <5d13cab5-1f0a-51c7-78a3-fb5d3d793ab1@linux.intel.com> <80457871-a760-69ba-70be-5e95344182ea@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/6/21 13:48, Tian, Kevin wrote: >> From: Baolu Lu >> Sent: Tuesday, June 21, 2022 12:28 PM >> >> On 2022/6/21 11:46, Tian, Kevin wrote: >>>> From: Baolu Lu >>>> Sent: Tuesday, June 21, 2022 11:39 AM >>>> >>>> On 2022/6/21 10:54, Tian, Kevin wrote: >>>>>> From: Lu Baolu >>>>>> Sent: Monday, June 20, 2022 4:17 PM >>>>>> @@ -2564,7 +2564,7 @@ static int domain_add_dev_info(struct >>>>>> dmar_domain *domain, struct device *dev) >>>>>> ret = intel_pasid_setup_second_level(iommu, >>>>>> domain, >>>>>> dev, PASID_RID2PASID); >>>>>> spin_unlock_irqrestore(&iommu->lock, flags); >>>>>> - if (ret) { >>>>>> + if (ret && ret != -EBUSY) { >>>>>> dev_err(dev, "Setup RID2PASID failed\n"); >>>>>> dmar_remove_one_dev_info(dev); >>>>>> return ret; >>>>>> -- >>>>>> 2.25.1 >>>>> >>>>> It's cleaner to avoid this error at the first place, i.e. only do the >>>>> setup when the first device is attached to the pasid table. >>>> >>>> The logic that identifies the first device might introduce additional >>>> unnecessary complexity. Devices that share a pasid table are rare. I >>>> even prefer to give up sharing tables so that the code can be >>>> simpler.:-) >>>> >>> >>> It's not that complex if you simply move device_attach_pasid_table() >>> out of intel_pasid_alloc_table(). Then do the setup if >>> list_empty(&pasid_table->dev) and then attach device to the >>> pasid table in domain_add_dev_info(). >> >> The pasid table is part of the device, hence a better place to >> allocate/free the pasid table is in the device probe/release paths. >> Things will become more complicated if we change relationship between >> device and it's pasid table when attaching/detaching a domain. That's >> the reason why I thought it was additional complexity. >> > > If you do want to follow current route it’s still cleaner to check > whether the pasid entry has pointed to the domain in the individual > setup function instead of blindly returning -EBUSY and then ignoring > it even if a real busy condition occurs. The setup functions can > just return zero for this benign alias case. Fair enough. Let me improve it. -- Best regards, baolu