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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14D98C04EBF for ; Thu, 6 Dec 2018 01:17:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD6DA214C1 for ; Thu, 6 Dec 2018 01:17:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CD6DA214C1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728771AbeLFBRA (ORCPT ); Wed, 5 Dec 2018 20:17:00 -0500 Received: from mga11.intel.com ([192.55.52.93]:23424 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727575AbeLFBQ7 (ORCPT ); Wed, 5 Dec 2018 20:16:59 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Dec 2018 17:16:59 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,320,1539673200"; d="scan'208";a="116392589" Received: from allen-box.sh.intel.com (HELO [10.239.161.122]) ([10.239.161.122]) by FMSMGA003.fm.intel.com with ESMTP; 05 Dec 2018 17:16:57 -0800 Cc: baolu.lu@linux.intel.com, "Liu, Yi L" , David Woodhouse , "Raj, Ashok" , "Kumar, Sanjay K" , "Pan, Jacob jun" , "Tian, Kevin" , "Sun, Yi Y" , "peterx@redhat.com" , Jean-Philippe Brucker , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , Jacob Pan Subject: Re: [PATCH v5 02/12] iommu/vt-d: Manage scalalble mode PASID tables To: Joerg Roedel References: <20181128035449.10226-1-baolu.lu@linux.intel.com> <20181128035449.10226-3-baolu.lu@linux.intel.com> <20181203134411.lejlkbnagxml54ro@8bytes.org> <5c81008b-30e8-177d-0182-db366608562f@linux.intel.com> <20181205155012.GC16835@8bytes.org> From: Lu Baolu Message-ID: Date: Thu, 6 Dec 2018 09:13:50 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181205155012.GC16835@8bytes.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Joerg, On 12/5/18 11:50 PM, Joerg Roedel wrote: > On Tue, Dec 04, 2018 at 01:58:06PM +0800, Lu Baolu wrote: >> This function is called in an unsleepable context. >> >> spin_lock(&lock) >> [...] >> if (pasid_table_is_necessary) >> allocate_pasid_table(dev) >> [...] >> spin_unlock(&lock) >> >> We can move it out of the lock range. >> >> How about >> >> if (pasid_table_is_necessary) >> pasid_table = allocate_pasid_table(dev) >> >> spin_lock(&lock) >> [...] >> if (pasid_table_is_necessary) >> set_up_pasid_table(pasid_table) >> [...] >> spin_unlock(&lock) > > Hmm, so when the IOMMU is configured in scalable mode we can just > allocate a pasid-table for the device when we set it up, right? > > Scalable mode is a boot-time decision, so we know for sure whether we > need a pasid-table on device-setup time. And the device-setup code it > preemptable, so I think it this allocation should be outside of any > spin-locked section. Fair enough. I will fix this up in the next version. Thank you for pointing this out. Best regards, Lu Baolu