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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 6249CC433DB for ; Thu, 28 Jan 2021 15:24:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1888F64DF4 for ; Thu, 28 Jan 2021 15:24:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232517AbhA1PYQ (ORCPT ); Thu, 28 Jan 2021 10:24:16 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:11530 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232178AbhA1PWP (ORCPT ); Thu, 28 Jan 2021 10:22:15 -0500 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DRPKs1ZVgzjFdr; Thu, 28 Jan 2021 23:20:17 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.498.0; Thu, 28 Jan 2021 23:21:20 +0800 Subject: Re: [PATCH v3 2/2] vfio/iommu_type1: Fix some sanity checks in detach group To: Alex Williamson References: <20210122092635.19900-1-zhukeqian1@huawei.com> <20210122092635.19900-3-zhukeqian1@huawei.com> <20210127164641.36e17bf5@omen.home.shazbot.org> 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 , , From: Keqian Zhu Message-ID: <5093dace-4b8a-d455-ba16-d0c2da755573@huawei.com> Date: Thu, 28 Jan 2021 23:21:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210127164641.36e17bf5@omen.home.shazbot.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/1/28 7:46, Alex Williamson wrote: > On Fri, 22 Jan 2021 17:26:35 +0800 > Keqian Zhu wrote: > >> vfio_sanity_check_pfn_list() is used to check whether pfn_list and >> notifier are empty when remove the external domain, so it makes a >> wrong assumption that only external domain will use the pinning >> interface. >> >> Now we apply the pfn_list check when a vfio_dma is removed and apply >> the notifier check when all domains are removed. >> >> Fixes: a54eb55045ae ("vfio iommu type1: Add support for mediated devices") >> Signed-off-by: Keqian Zhu >> --- >> drivers/vfio/vfio_iommu_type1.c | 33 ++++++++++----------------------- >> 1 file changed, 10 insertions(+), 23 deletions(-) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index 161725395f2f..d8c10f508321 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -957,6 +957,7 @@ 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); >> @@ -2250,23 +2251,6 @@ 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 >> @@ -2366,10 +2350,10 @@ 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); >> - >> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) >> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) { >> + WARN_ON(iommu->notifier.head); >> vfio_iommu_unmap_unpin_all(iommu); >> + } >> >> kfree(iommu->external_domain); >> iommu->external_domain = NULL; >> @@ -2403,10 +2387,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >> */ >> if (list_empty(&domain->group_list)) { >> if (list_is_singular(&iommu->domain_list)) { >> - if (!iommu->external_domain) >> + if (!iommu->external_domain) { >> + WARN_ON(iommu->notifier.head); >> vfio_iommu_unmap_unpin_all(iommu); >> - else >> + } else { >> vfio_iommu_unmap_unpin_reaccount(iommu); >> + } >> } >> iommu_domain_free(domain->domain); >> list_del(&domain->next); >> @@ -2488,9 +2474,10 @@ static void vfio_iommu_type1_release(void *iommu_data) >> struct vfio_iommu *iommu = iommu_data; >> struct vfio_domain *domain, *domain_tmp; >> >> + WARN_ON(iommu->notifier.head); > > I don't see that this does any harm, but isn't it actually redundant? > It seems vfio-core only calls the iommu backend release function after > removing all the groups, so the tests in _detach_group should catch all > cases. We're expecting the vfio bus/mdev driver to remove the notifier > when a device is closed, which necessarily occurs before detaching the > group. Thanks, > > Alex Hi Alex, Sorry that today I was busy at sending the smmu HTTU based dma dirty log tracking. I will reply you tomorrow. Thanks! Keqian. > >> + >> if (iommu->external_domain) { >> vfio_release_domain(iommu->external_domain, true); >> - vfio_sanity_check_pfn_list(iommu); >> kfree(iommu->external_domain); >> } >> > > . >