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 0A168C433F5 for ; Thu, 12 May 2022 11:59:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353476AbiELL7w (ORCPT ); Thu, 12 May 2022 07:59:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239193AbiELL7t (ORCPT ); Thu, 12 May 2022 07:59:49 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBF41217FCA for ; Thu, 12 May 2022 04:59:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652356787; x=1683892787; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=2xpqBipggE9efSrMnAk1RxaKgm4Z25yOtIHM0l1ipSE=; b=D0H5/tLr9KKVS0ruxCZKIYIMnIrKdAaeVJfuzVl9AbIlc1Hx0jbd0k87 3PJE3rNATfgzLWvHq/2BGFgRTccKz71gXhCnMC43Av5j4Pflwvo4nQ2Fl ZJ8Ns4CklSy48Qw9KSDXLGgX+yS6/SdCHWByL7nxmQZt5VgghI4n2MIgt 5SNziVIlVl1N/XFamqwiOrJNwpOD/ffU2Hy8WECx5GSMcIxhIeGd7ZM9W So9D+TgWQcbyrfhbJeQidpEjyvpZhOel6cpctEjeUx54Ti6wwTMSzK2wE LoboHGZm4EnN28s23D/04e7RtsL+4MANGmac9VPtSoE5wfS5qXve2jLQC Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10344"; a="356404381" X-IronPort-AV: E=Sophos;i="5.91,219,1647327600"; d="scan'208";a="356404381" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2022 04:59:47 -0700 X-IronPort-AV: E=Sophos;i="5.91,219,1647327600"; d="scan'208";a="594633931" 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; 12 May 2022 04:59:43 -0700 Message-ID: <1a78418a-8637-e8dd-d1de-5529f20058fd@linux.intel.com> Date: Thu, 12 May 2022 19:59:41 +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, "Tian, Kevin" , 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: 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> <20220512114844.GT49344@nvidia.com> From: Baolu Lu In-Reply-To: <20220512114844.GT49344@nvidia.com> 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 19:48, Jason Gunthorpe wrote: > On Thu, May 12, 2022 at 01:17:08PM +0800, Baolu Lu wrote: >> 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. > > Why would we have a special unbind for SVA? It's about SVA kAPI for device drivers. The existing kAPIs include: struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata); void iommu_sva_unbind_device(struct iommu_sva *handle); u32 iommu_sva_get_pasid(struct iommu_sva *handle); > SVA should not different from normal domains it should use the normal > detach flow too. Best regards, baolu