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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 AC187C3A5A8 for ; Wed, 4 Sep 2019 07:59:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61F9720820 for ; Wed, 4 Sep 2019 07:59:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=shipmail.org header.i=@shipmail.org header.b="IQ61v1gT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729235AbfIDH7L (ORCPT ); Wed, 4 Sep 2019 03:59:11 -0400 Received: from ste-pvt-msa2.bahnhof.se ([213.80.101.71]:1160 "EHLO ste-pvt-msa2.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728909AbfIDH7L (ORCPT ); Wed, 4 Sep 2019 03:59:11 -0400 Received: from localhost (localhost [127.0.0.1]) by ste-pvt-msa2.bahnhof.se (Postfix) with ESMTP id 0DE733F5F0; Wed, 4 Sep 2019 09:59:10 +0200 (CEST) Authentication-Results: ste-pvt-msa2.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=IQ61v1gT; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se Authentication-Results: ste-ftg-msa2.bahnhof.se (amavisd-new); dkim=pass (1024-bit key) header.d=shipmail.org Received: from ste-pvt-msa2.bahnhof.se ([127.0.0.1]) by localhost (ste-ftg-msa2.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id VlwumVT_5Fq4; Wed, 4 Sep 2019 09:59:09 +0200 (CEST) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by ste-pvt-msa2.bahnhof.se (Postfix) with ESMTPA id BEF383F346; Wed, 4 Sep 2019 09:59:08 +0200 (CEST) Received: from localhost.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 847A536117F; Wed, 4 Sep 2019 09:59:08 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1567583948; bh=u13FcfsPPB+rHX6dHh07axBYmf9RAYcEXi36fo/oS+E=; h=To:Cc:From:Subject:Date:From; b=IQ61v1gTFy6dWmoVldP8ckGJ3X2qWRd+BKgDVG3BVpcHQy5IONzEICcwffHpL5pEl ciM4ra7cN3gxcTvsHkXON0Ol7lKJ7hsK8OVCKMSDUSBnFj2HZNtX9X0FzH0+adWEBA R0JNPmR1kyNo1bykPHpgzj0ZzCC37gdLTILuy1Zk= To: Christoph Hellwig Cc: "linux-kernel@vger.kernel.org" From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28VMware=29?= Subject: dma api errors with swiotlb Organization: VMware Inc. Message-ID: Date: Wed, 4 Sep 2019 09:59:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Cristoph. Another DMA related question before I start to post patches in this area again.. Our virtual SCSI device (which BTW is fully DMA compliant) has a large queue depth and therefore runs out of SWIOTLB space => The scsi middle layer behaves nicely and asks the driver to retry the dma mapping operation. All fine. The problem is that while this happens, the kernel log spits out a number of dma- and SWIOTLB errors, which are really harmless. While one could probably just say go and increase the SWIOTLB size, but on some systems that might not be doable. We could reduce the queue depth when SEV is active, which is probably one of those hacky solutions you dislike. We could silence the dma- and swiotlb errors? At least selectively for some devices? Do you have any guidance into the best solution here? Thanks, Thomas.