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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17A1CC433F5 for ; Wed, 17 Nov 2021 05:26:59 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 891E561A0D for ; Wed, 17 Nov 2021 05:26:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 891E561A0D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 45B0B80F65; Wed, 17 Nov 2021 05:26:58 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id m0vh-nEawZ9y; Wed, 17 Nov 2021 05:26:57 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTPS id 18F1C80EEE; Wed, 17 Nov 2021 05:26:57 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id DADDDC001E; Wed, 17 Nov 2021 05:26:56 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3FE39C0012 for ; Wed, 17 Nov 2021 05:26:55 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 19FDA40139 for ; Wed, 17 Nov 2021 05:26:55 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id H3p-9_n0ZxWC for ; Wed, 17 Nov 2021 05:26:53 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by smtp2.osuosl.org (Postfix) with ESMTPS id 05182400F6 for ; Wed, 17 Nov 2021 05:26:52 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10170"; a="257647743" X-IronPort-AV: E=Sophos;i="5.87,240,1631602800"; d="scan'208";a="257647743" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Nov 2021 21:26:51 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,240,1631602800"; d="scan'208";a="494772632" Received: from allen-box.sh.intel.com (HELO [10.239.159.118]) ([10.239.159.118]) by orsmga007.jf.intel.com with ESMTP; 16 Nov 2021 21:26:46 -0800 Subject: Re: [PATCH 01/11] iommu: Add device dma ownership set/release interfaces To: Jason Gunthorpe References: <20211115020552.2378167-1-baolu.lu@linux.intel.com> <20211115020552.2378167-2-baolu.lu@linux.intel.com> <20211116134603.GA2105516@nvidia.com> From: Lu Baolu Message-ID: Date: Wed, 17 Nov 2021 13:22:19 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211116134603.GA2105516@nvidia.com> Content-Language: en-US Cc: Kevin Tian , Chaitanya Kulkarni , Ashok Raj , kvm@vger.kernel.org, rafael@kernel.org, Greg Kroah-Hartman , Cornelia Huck , Will Deacon , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Christoph Hellwig , Alex Williamson , Jacob jun Pan , linux-pci@vger.kernel.org, Bjorn Helgaas , Diana Craciun 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Jason, On 11/16/21 9:46 PM, Jason Gunthorpe wrote: > On Tue, Nov 16, 2021 at 09:57:30AM +0800, Lu Baolu wrote: >> Hi Christoph, >> >> On 11/15/21 9:14 PM, Christoph Hellwig wrote: >>> On Mon, Nov 15, 2021 at 10:05:42AM +0800, Lu Baolu wrote: >>>> +enum iommu_dma_owner { >>>> + DMA_OWNER_NONE, >>>> + DMA_OWNER_KERNEL, >>>> + DMA_OWNER_USER, >>>> +}; >>>> + >>> >>>> + enum iommu_dma_owner dma_owner; >>>> + refcount_t owner_cnt; >>>> + struct file *owner_user_file; >>> >>> I'd just overload the ownership into owner_user_file, >>> >>> NULL -> no owner >>> (struct file *)1UL) -> kernel >>> real pointer -> user >>> >>> Which could simplify a lot of the code dealing with the owner. >>> >> >> Yeah! Sounds reasonable. I will make this in the next version. > > It would be good to figure out how to make iommu_attach_device() > enforce no other driver binding as a kernel user without a file *, as > Robin pointed to, before optimizing this. > > This fixes an existing bug where iommu_attach_device() only checks the > group size and is vunerable to a hot plug increasing the group size > after it returns. That check should be replaced by this series's logic > instead. As my my understanding, the essence of this problem is that only the user owner of the iommu_group could attach an UNMANAGED domain to it. If I understand it right, how about introducing a new interface to allocate a user managed domain and storing the user file pointer in it. --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -94,6 +94,7 @@ struct iommu_domain { void *handler_token; struct iommu_domain_geometry geometry; struct iommu_dma_cookie *iova_cookie; + struct file *owner_user_file; }; --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1902,6 +1902,18 @@ struct iommu_domain *iommu_domain_alloc(struct bus_type *bus) } EXPORT_SYMBOL_GPL(iommu_domain_alloc); +struct iommu_domain *iommu_domain_alloc_user(struct bus_type *bus, + struct file *filep) +{ + struct iommu_domain *domain; + + domain = __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED); + if (domain) + domain->owner_user_file = filep; + + return domain; +} When attaching a domain to an user-owned iommu_group, both group and domain should have matched user fd. Does above help here? Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu