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bh=OnCFlVZKT1kcPJl0tm16QfqztTjiCxEfefQVkmAO2Q4=; b=F+54tsoLXnprRNxJwQMKk+GDOP7FcUV1nZhgZ5hb4qxvCcpBv3w+nH+D+a9ZHVU5gO807e Cn1nKRlvzU+ahsaQRqa0Y3NF8Bq7fBm2X/DEnJ02I5KupT5SWSWFoChXYdCebF7ufaQicr oqbqpdqc/Gp1gj0ECYasH79HMCJQ620= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-301--znvfP_QP-a_NK8x7vIE7A-1; Fri, 17 Apr 2020 03:47:03 -0400 X-MC-Unique: -znvfP_QP-a_NK8x7vIE7A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 116C118B9FC8; Fri, 17 Apr 2020 07:47:02 +0000 (UTC) Received: from [10.36.115.53] (ovpn-115-53.ams2.redhat.com [10.36.115.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E56D9129F81; Fri, 17 Apr 2020 07:46:56 +0000 (UTC) Subject: Re: [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support To: "Tian, Kevin" , Jacob Pan References: <1585939334-21396-1-git-send-email-jacob.jun.pan@linux.intel.com> <1585939334-21396-6-git-send-email-jacob.jun.pan@linux.intel.com> <20200410124557.4012b99b@jacob-builder> <6d9721a8-2198-5ecd-6c8b-fc43ff2ad7e1@redhat.com> From: Auger Eric Message-ID: <2025736d-e7f2-d746-e030-e609b2f465e2@redhat.com> Date: Fri, 17 Apr 2020 09:46:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Cc: Yi L , "Raj, Ashok" , Jean-Philippe Brucker , "iommu@lists.linux-foundation.org" , LKML , Alex Williamson , David Woodhouse , Jonathan Cameron 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" Hi Kevin, On 4/17/20 4:45 AM, Tian, Kevin wrote: >> From: Auger Eric >> Sent: Thursday, April 16, 2020 6:43 PM >> > [...] >>>>> + if (svm) { >>>>> + /* >>>>> + * If we found svm for the PASID, there must be at >>>>> + * least one device bond, otherwise svm should be >>>>> freed. >>>>> + */ >>>>> + if (WARN_ON(list_empty(&svm->devs))) { >>>>> + ret = -EINVAL; >>>>> + goto out; >>>>> + } >>>>> + >>>>> + for_each_svm_dev(sdev, svm, dev) { >>>>> + /* In case of multiple sub-devices of the >>>>> same pdev >>>>> + * assigned, we should allow multiple bind >>>>> calls with >>>>> + * the same PASID and pdev. >>>>> + */ >>>>> + sdev->users++; >>>> What if this is not an mdev device. Is it also allowed? >>> Yes. IOMMU and VT-d driver is not mdev aware. Here mdev is just an >>> example of normal use case. You can bind the same PCI device (PF or >>> SRIOV VF) more than once to the same PASID. Just need to unbind also. >> >> I don't get the point of binding a non mdev device several times with >> the same PASID. Do you intend to allow that at userspace level or >> prevent this from happening in VFIO? > > I feel it's better to prevent this from happening, otherwise VFIO also > needs to track the bind count and do multiple unbinds at mm_exit. > But it's not necessary to prevent it in VFIO. We can check here > upon whether aux_domain is valid, and if not return -EBUSY. Ah OK. So if we can detect the case here it is even better Thanks Eric > >> >> Besides, the comment is a bit misleading as it gives the impression it >> is only true for mdev and there is no associated check. > > Thanks > Kevin > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu