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=-2.3 required=3.0 tests=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 5C711C11D0C for ; Thu, 20 Feb 2020 16:32:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FC9520722 for ; Thu, 20 Feb 2020 16:32:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728942AbgBTQbl (ORCPT ); Thu, 20 Feb 2020 11:31:41 -0500 Received: from verein.lst.de ([213.95.11.211]:50298 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728925AbgBTQbj (ORCPT ); Thu, 20 Feb 2020 11:31:39 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 07B1C68BFE; Thu, 20 Feb 2020 17:31:36 +0100 (CET) Date: Thu, 20 Feb 2020 17:31:35 +0100 From: Christoph Hellwig To: Christian Borntraeger Cc: Christoph Hellwig , Halil Pasic , "Michael S. Tsirkin" , Jason Wang , Marek Szyprowski , Robin Murphy , linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Janosch Frank , Viktor Mihajlovski , Cornelia Huck , Ram Pai , Thiago Jung Bauermann , David Gibson , "Lendacky, Thomas" , Michael Mueller Subject: Re: [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h Message-ID: <20200220163135.GA13192@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-2-pasic@linux.ibm.com> <20200220161146.GA12709@lst.de> <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote: > >From a users perspective it makes absolutely perfect sense to use the > bounce buffers when they are NEEDED. > Forcing the user to specify iommu_platform just because you need bounce buffers > really feels wrong. And obviously we have a severe performance issue > because of the indirections. The point is that the user should not have to specify iommu_platform. We need to make sure any new hypervisor (especially one that might require bounce buffering) always sets it, as was a rather bogus legacy hack that isn't extensibe for cases that for example require bounce buffering. 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=-2.3 required=3.0 tests=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 E6FA8C11D05 for ; Thu, 20 Feb 2020 16:31:44 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B6C8B206F4 for ; Thu, 20 Feb 2020 16:31:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B6C8B206F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id A0CDD85D3A; Thu, 20 Feb 2020 16:31:43 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zhXfiEw_Onhq; Thu, 20 Feb 2020 16:31:43 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 33B0685C97; Thu, 20 Feb 2020 16:31:43 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 10E58C1D81; Thu, 20 Feb 2020 16:31:43 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id C0B92C013E; Thu, 20 Feb 2020 16:31:41 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id BBE8785D3A; Thu, 20 Feb 2020 16:31:41 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id oD9jkA968iLI; Thu, 20 Feb 2020 16:31:40 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 708BE85C97; Thu, 20 Feb 2020 16:31:40 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 07B1C68BFE; Thu, 20 Feb 2020 17:31:36 +0100 (CET) Date: Thu, 20 Feb 2020 17:31:35 +0100 From: Christoph Hellwig To: Christian Borntraeger Subject: Re: [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h Message-ID: <20200220163135.GA13192@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-2-pasic@linux.ibm.com> <20200220161146.GA12709@lst.de> <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-s390@vger.kernel.org, Janosch Frank , "Michael S. Tsirkin" , Jason Wang , Cornelia Huck , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Halil Pasic , iommu@lists.linux-foundation.org, David Gibson , Michael Mueller , "Lendacky, Thomas" , Viktor Mihajlovski , Robin Murphy , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote: > >From a users perspective it makes absolutely perfect sense to use the > bounce buffers when they are NEEDED. > Forcing the user to specify iommu_platform just because you need bounce buffers > really feels wrong. And obviously we have a severe performance issue > because of the indirections. The point is that the user should not have to specify iommu_platform. We need to make sure any new hypervisor (especially one that might require bounce buffering) always sets it, as was a rather bogus legacy hack that isn't extensibe for cases that for example require bounce buffering. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h Date: Thu, 20 Feb 2020 17:31:35 +0100 Message-ID: <20200220163135.GA13192@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-2-pasic@linux.ibm.com> <20200220161146.GA12709@lst.de> <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" To: Christian Borntraeger Cc: linux-s390@vger.kernel.org, Janosch Frank , "Michael S. Tsirkin" , Cornelia Huck , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Halil Pasic , iommu@lists.linux-foundation.org, David Gibson , Michael Mueller , "Lendacky, Thomas" , Viktor Mihajlovski , Robin Murphy , Christoph Hellwig , Marek Szyprowski List-Id: virtualization@lists.linuxfoundation.org On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote: > >From a users perspective it makes absolutely perfect sense to use the > bounce buffers when they are NEEDED. > Forcing the user to specify iommu_platform just because you need bounce buffers > really feels wrong. And obviously we have a severe performance issue > because of the indirections. The point is that the user should not have to specify iommu_platform. We need to make sure any new hypervisor (especially one that might require bounce buffering) always sets it, as was a rather bogus legacy hack that isn't extensibe for cases that for example require bounce buffering.