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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 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 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210115_141459_874574_FB567C16 X-CRM114-Status: GOOD ( 24.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , jiangkunkun@huawei.com, kvm@vger.kernel.org, Catalin Marinas , Kirti Wankhede , Will Deacon , kvmarm@lists.cs.columbia.edu, Marc Zyngier , Joerg Roedel , Daniel Lezcano , wanghaibin.wang@huawei.com, Julien Thierry , Suzuki K Poulose , Alexios Zavras , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Cornelia Huck , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, James Morse , Andrew Morton , Robin Murphy Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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); > } > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel