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 2F489C678D5 for ; Wed, 8 Mar 2023 13:48:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230360AbjCHNso (ORCPT ); Wed, 8 Mar 2023 08:48:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229770AbjCHNsl (ORCPT ); Wed, 8 Mar 2023 08:48:41 -0500 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 695C419B5; Wed, 8 Mar 2023 05:48:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1678283309; x=1709819309; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=sML0Jp0ngAS0AophUFs7GWR5Tb8f53bTkEbS39Vp9L0=; b=molrG+6tL67tPHNUDJKdFybWoTC+NjtoF2dLW7TU0ay5iFTHdWeFu0XK yApWmck506WYKmMZ76+wRZDgjmz0Qi6dDVmb/cI5ao+z0C8XP7YJdAiKB UTKvGAqWJcO88/Yr/513hyTlt3Dm60UcVKVk5PIYXrcjGwvNohK5Nip9Y V3x1eJJT7oazYLphYoKjY+W0pENbRQ8g/wLHI7Wouggyd67RR1pzSm+W2 Ecx4XV6tO3XO9MDfTsIGG+U2ANRK2z7gtgN6VXFZeyioABNBntkEhrPSN ZJccs5Nl7TRc++g6iEZeV7xz05EGtyqvb57F351R+6DCKZ3Waozf78/18 Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10642"; a="422423687" X-IronPort-AV: E=Sophos;i="5.98,244,1673942400"; d="scan'208";a="422423687" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2023 05:48:14 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10642"; a="851089149" X-IronPort-AV: E=Sophos;i="5.98,244,1673942400"; d="scan'208";a="851089149" Received: from blu2-mobl.ccr.corp.intel.com (HELO [10.254.208.136]) ([10.254.208.136]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2023 05:48:12 -0800 Message-ID: <74bdf564-cdfe-8416-6b20-b4f18d461799@linux.intel.com> Date: Wed, 8 Mar 2023 21:48:10 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Cc: baolu.lu@linux.intel.com, kvm@vger.kernel.org, Nicolin Chen , Yi Liu Subject: Re: [PATCH v2 11/17] iommu: Introduce a new iommu_group_replace_domain() API Content-Language: en-US To: Jason Gunthorpe , iommu@lists.linux.dev, Kevin Tian , linux-kselftest@vger.kernel.org References: <11-v2-51b9896e7862+8a8c-iommufd_alloc_jgg@nvidia.com> From: Baolu Lu In-Reply-To: <11-v2-51b9896e7862+8a8c-iommufd_alloc_jgg@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 2023/3/8 8:35, Jason Gunthorpe wrote: > From: Nicolin Chen > > qemu has a need to replace the translations associated with a domain > when the guest does large-scale operations like switching between an > IDENTITY domain and, say, dma-iommu.c. > > Currently, it does this by replacing all the mappings in a single > domain, but this is very inefficient and means that domains have to be > per-device rather than per-translation. > > Provide a high-level API to allow replacements of one domain with > another. This is similar to a detach/attach cycle except it doesn't > force the group to go to the blocking domain in-between. > > By removing this forced blocking domain the iommu driver has the > opportunity to implement a non-disruptive replacement of the domain to the > greatest extent its hardware allows. This allows the qemu emulation of the > vIOMMU to be more complete, as real hardware often has a non-distruptive > replacement capability. > > It could be possible to address this by simply removing the protection > from the iommu_attach_group(), but it is not so clear if that is safe for > the few users. Thus, add a new API to serve this new purpose. > > All drivers are already required to support changing between active > UNMANAGED domains when using their attach_dev ops. > > This API is expected to be used only by IOMMUFD, so add to the iommu-priv > header and mark it as IOMMUFD_INTERNAL. > > Suggested-by: Jason Gunthorpe > Reviewed-by: Kevin Tian > Signed-off-by: Nicolin Chen > Signed-off-by: Jason Gunthorpe Reviewed-by: Lu Baolu Best regards, baolu