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 X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02C07C4332B for ; Fri, 15 Jan 2021 19:16:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFC8A23A5E for ; Fri, 15 Jan 2021 19:16:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387921AbhAOTQX (ORCPT ); Fri, 15 Jan 2021 14:16:23 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:56325 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726541AbhAOTQX (ORCPT ); Fri, 15 Jan 2021 14:16:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610738096; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=v4FwxeAEyXEI6CWznvqU5AtMWFcpWnT8O1IOjG3Vr1Y=; b=NO6McH48ardHju9sMXHupcDuh6pwTCoRH5AgZxbKyA5QFzDmGZjdr64BNKjaTfYeEKkjCY FdpJUeI2TuwKEG6ny/1kjluykJSZJC84Dqq6El6pHIjyCbqoKrYX2PEBOxqDlVOTT1sM5v IqXBLXbSXoA8aoG0c+v3+Y8tvlDYehM= 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-246-QqrpG32lOIWZOPK7xYEGTg-1; Fri, 15 Jan 2021 14:14:52 -0500 X-MC-Unique: QqrpG32lOIWZOPK7xYEGTg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 93C32806662; Fri, 15 Jan 2021 19:14:49 +0000 (UTC) Received: from omen.home.shazbot.org (ovpn-112-255.phx2.redhat.com [10.3.112.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id D6AFB5D9C6; Fri, 15 Jan 2021 19:14:47 +0000 (UTC) Date: Fri, 15 Jan 2021 12:14:47 -0700 From: Alex Williamson To: Keqian Zhu Cc: , , , , , Kirti Wankhede , Cornelia Huck , Will Deacon , Marc Zyngier , Catalin Marinas , Mark Rutland , James Morse , Robin Murphy , Joerg Roedel , "Daniel Lezcano" , Thomas Gleixner , Suzuki K Poulose , Julien Thierry , Andrew Morton , Alexios Zavras , , Subject: Re: [PATCH v2 2/2] vfio/iommu_type1: Sanity check pfn_list when remove vfio_dma Message-ID: <20210115121447.54c96857@omen.home.shazbot.org> In-Reply-To: <20210115092643.728-3-zhukeqian1@huawei.com> References: <20210115092643.728-1-zhukeqian1@huawei.com> <20210115092643.728-3-zhukeqian1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 15 Jan 2021 17:26:43 +0800 Keqian Zhu wrote: > vfio_sanity_check_pfn_list() is used to check whether pfn_list of > vfio_dma is empty when remove the external domain, so it makes a > wrong assumption that only external domain will add pfn to dma pfn_list. > > Now we apply this check when remove a specific vfio_dma and extract > the notifier check just for external domain. The page pinning interface is gated by having a notifier registered for unmaps, therefore non-external domains would also need to register a notifier. There's currently no other way to add entries to the pfn_list. So if we allow pinning for such domains, then it's wrong to WARN_ON() when the notifier list is not-empty when removing an external domain. Long term we should probably extend page {un}pinning for the caller to pass their notifier to be validated against the notifier list rather than just allowing page pinning if *any* notifier is registered. Thanks, Alex > Fixes: a54eb55045ae ("vfio iommu type1: Add support for mediated devices") > Signed-off-by: Keqian Zhu > --- > drivers/vfio/vfio_iommu_type1.c | 24 +++++------------------- > 1 file changed, 5 insertions(+), 19 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 4e82b9a3440f..a9bc15e84a4e 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -958,6 +958,7 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma, > > static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma) > { > + WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list); > vfio_unmap_unpin(iommu, dma, true); > vfio_unlink_dma(iommu, dma); > put_task_struct(dma->task); > @@ -2251,23 +2252,6 @@ static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu) > } > } > > -static void vfio_sanity_check_pfn_list(struct vfio_iommu *iommu) > -{ > - struct rb_node *n; > - > - n = rb_first(&iommu->dma_list); > - for (; n; n = rb_next(n)) { > - struct vfio_dma *dma; > - > - dma = rb_entry(n, struct vfio_dma, node); > - > - if (WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list))) > - break; > - } > - /* mdev vendor driver must unregister notifier */ > - WARN_ON(iommu->notifier.head); > -} > - > /* > * Called when a domain is removed in detach. It is possible that > * the removed domain decided the iova aperture window. Modify the > @@ -2367,7 +2351,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, > kfree(group); > > if (list_empty(&iommu->external_domain->group_list)) { > - vfio_sanity_check_pfn_list(iommu); > + /* mdev vendor driver must unregister notifier */ > + WARN_ON(iommu->notifier.head); > > if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) > vfio_iommu_unmap_unpin_all(iommu); > @@ -2491,7 +2476,8 @@ static void vfio_iommu_type1_release(void *iommu_data) > > if (iommu->external_domain) { > vfio_release_domain(iommu->external_domain, true); > - vfio_sanity_check_pfn_list(iommu); > + /* mdev vendor driver must unregister notifier */ > + WARN_ON(iommu->notifier.head); > kfree(iommu->external_domain); > } >