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 CC1EBC433F5 for ; Thu, 12 May 2022 06:16:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350217AbiELGQp (ORCPT ); Thu, 12 May 2022 02:16:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234728AbiELGQn (ORCPT ); Thu, 12 May 2022 02:16:43 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C83759398C for ; Wed, 11 May 2022 23:16:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652336202; x=1683872202; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=g6IIn5TcCQm3tWIL9ibzyttiUg0lLF5CJ9+P8r5+AbE=; b=VXnnD1STRCpb8fdPqzKN69502lC6sQpjpf9aLALQhAq5IEJZseIojGM6 QYPbZENLfjdixI47BANIKzf4qTfhimSyvqqqFSIcfJEkiEBzYVdkt3GdA Yij9JdaruAMiMVD9Ziy3lReoAupopqmItnqRuOIEwU1WROlL+LTjPcVoZ q5JEsFkHc9fgzivXefQEB0m9epMSAQEEJLeltqh/BaceI4dvhk6J544g0 CVnrOErdyqgcIAXR5lAuBaNxA3GeAKVko24uWJbbJwlXnfrz8YZ6NIpxB bbgf3coWagcw4VQCQORTHgTxK/N7Wv2DV4hqHLerPZ1myWuCV1Q/fUaWn g==; X-IronPort-AV: E=McAfee;i="6400,9594,10344"; a="356327881" X-IronPort-AV: E=Sophos;i="5.91,218,1647327600"; d="scan'208";a="356327881" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 May 2022 23:16:42 -0700 X-IronPort-AV: E=Sophos;i="5.91,218,1647327600"; d="scan'208";a="594513911" Received: from hezhu1-mobl1.ccr.corp.intel.com (HELO [10.255.29.168]) ([10.255.29.168]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 May 2022 23:16:37 -0700 Message-ID: <0170bf39-5c1b-c4d5-631d-2afe98a5de61@linux.intel.com> Date: Thu, 12 May 2022 14:16:36 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Cc: baolu.lu@linux.intel.com, Joerg Roedel , Christoph Hellwig , "Raj, Ashok" , Will Deacon , Robin Murphy , Jean-Philippe Brucker , "Jiang, Dave" , Vinod Koul , Eric Auger , "Liu, Yi L" , "Pan, Jacob jun" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v6 08/12] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces Content-Language: en-US To: "Tian, Kevin" , Jason Gunthorpe References: <20220510061738.2761430-1-baolu.lu@linux.intel.com> <20220510061738.2761430-9-baolu.lu@linux.intel.com> <20220510152330.GG49344@nvidia.com> <749a7d62-3e6c-ef5c-beaf-6b7add495740@linux.intel.com> <20220511145319.GZ49344@nvidia.com> <05a68e1e-8e18-5914-ebe7-d7b1a4aaa2ec@linux.intel.com> <64954f2d-2274-410e-269c-84efc0635633@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/5/12 13:44, Tian, Kevin wrote: >> From: Baolu Lu >> Sent: Thursday, May 12, 2022 1:17 PM >> >> On 2022/5/12 13:01, Tian, Kevin wrote: >>>> From: Baolu Lu >>>> Sent: Thursday, May 12, 2022 11:03 AM >>>> >>>> On 2022/5/11 22:53, Jason Gunthorpe wrote: >>>>>>> Also, given the current arrangement it might make sense to have a >>>>>>> struct iommu_domain_sva given that no driver is wrappering this in >>>>>>> something else. >>>>>> Fair enough. How about below wrapper? >>>>>> >>>>>> +struct iommu_sva_domain { >>>>>> + /* >>>>>> + * Common iommu domain header,*must* be put at the top >>>>>> + * of the structure. >>>>>> + */ >>>>>> + struct iommu_domain domain; >>>>>> + struct mm_struct *mm; >>>>>> + struct iommu_sva bond; >>>>>> +} >>>>>> >>>>>> The refcount is wrapped in bond. >>>>> I'm still not sure that bond is necessary >>>> >>>> "bond" is the sva handle that the device drivers get through calling >>>> iommu_sva_bind(). >>>> >>> >>> 'bond' was required before because we didn't have a domain to wrap >>> the page table at that time. >>> >>> Now we have a domain and it is 1:1 associated to bond. Probably >>> make sense now by just returning the domain as the sva handle >>> instead? >> >> It also includes the device information that the domain has been >> attached. So the sva_unbind() looks like this: >> >> /** >> * iommu_sva_unbind_device() - Remove a bond created with >> iommu_sva_bind_device >> * @handle: the handle returned by iommu_sva_bind_device() >> * >> * Put reference to a bond between device and address space. The device >> should >> * not be issuing any more transaction for this PASID. All outstanding page >> * requests for this PASID must have been flushed to the IOMMU. >> */ >> void iommu_sva_unbind_device(struct iommu_sva *handle) >> >> It's fine to replace the iommu_sva with iommu_sva_domain for sva handle, >> if we can include the device in the unbind() interface. > > can we just have unbind(domain, device)? Yes. With this, we can remove bond. This could be done in below phase 2. > >> >> Anyway, I'd expect to achieve all these in two steps: >> >> - sva and iopf refactoring, only iommu internal changes; >> - sva interface refactoring, only interface changes. >> >> Does above work? >> >> Best regards, >> baolu Best regards, baolu