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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 72DFBC433DF for ; Thu, 2 Jul 2020 18:39:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 409FD20772 for ; Thu, 2 Jul 2020 18:39:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Sr7FQmAn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726074AbgGBSjH (ORCPT ); Thu, 2 Jul 2020 14:39:07 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:44281 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725878AbgGBSjG (ORCPT ); Thu, 2 Jul 2020 14:39:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593715144; 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=QinCx818pF5X1BdSH0zzsKcBs7VYqRNInJzgnq1e7DU=; b=Sr7FQmAnY4kgOranzBLE5H3dWxu5PlkzYR3RUFcq6w9jBrJeME2erOlyGCDy8ED9u+Rncs 3QFHcgALkA6NQjdlwD930qmr23VeNL32Lx3UmdyQvXwLJwIoze5GL7P4UKhmyiSuLNfahY j4/VCzH/djDqHlQ5fhpaW2rrRfKdhSg= 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-350-HeEylAtSP3qHqeCAcVzSjA-1; Thu, 02 Jul 2020 14:38:58 -0400 X-MC-Unique: HeEylAtSP3qHqeCAcVzSjA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AE3F92E93; Thu, 2 Jul 2020 18:38:56 +0000 (UTC) Received: from x1.home (ovpn-112-156.phx2.redhat.com [10.3.112.156]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5BDD379254; Thu, 2 Jul 2020 18:38:48 +0000 (UTC) Date: Thu, 2 Jul 2020 12:38:47 -0600 From: Alex Williamson To: Liu Yi L Cc: eric.auger@redhat.com, baolu.lu@linux.intel.com, joro@8bytes.org, kevin.tian@intel.com, jacob.jun.pan@linux.intel.com, ashok.raj@intel.com, jun.j.tian@intel.com, yi.y.sun@intel.com, jean-philippe@linaro.org, peterx@redhat.com, hao.wu@intel.com, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 03/14] vfio/type1: Report iommu nesting info to userspace Message-ID: <20200702123847.384e7460@x1.home> In-Reply-To: <1592988927-48009-4-git-send-email-yi.l.liu@intel.com> References: <1592988927-48009-1-git-send-email-yi.l.liu@intel.com> <1592988927-48009-4-git-send-email-yi.l.liu@intel.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 24 Jun 2020 01:55:16 -0700 Liu Yi L wrote: > This patch exports iommu nesting capability info to user space through > VFIO. User space is expected to check this info for supported uAPIs (e.g. > PASID alloc/free, bind page table, and cache invalidation) and the vendor > specific format information for first level/stage page table that will be > bound to. > > The nesting info is available only after the nesting iommu type is set > for a container. Current implementation imposes one limitation - one > nesting container should include at most one group. The philosophy of > vfio container is having all groups/devices within the container share > the same IOMMU context. When vSVA is enabled, one IOMMU context could > include one 2nd-level address space and multiple 1st-level address spaces. > While the 2nd-leve address space is reasonably sharable by multiple groups > , blindly sharing 1st-level address spaces across all groups within the > container might instead break the guest expectation. In the future sub/ > super container concept might be introduced to allow partial address space > sharing within an IOMMU context. But for now let's go with this restriction > by requiring singleton container for using nesting iommu features. Below > link has the related discussion about this decision. > > https://lkml.org/lkml/2020/5/15/1028 > > Cc: Kevin Tian > CC: Jacob Pan > Cc: Alex Williamson > Cc: Eric Auger > Cc: Jean-Philippe Brucker > Cc: Joerg Roedel > Cc: Lu Baolu > Signed-off-by: Liu Yi L > --- > drivers/vfio/vfio_iommu_type1.c | 73 +++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/vfio.h | 9 +++++ > 2 files changed, 82 insertions(+) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 7accb59..8c143d5 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -72,6 +72,7 @@ struct vfio_iommu { > uint64_t pgsize_bitmap; > bool v2; > bool nesting; > + struct iommu_nesting_info *nesting_info; > bool dirty_page_tracking; > bool pinned_page_dirty_scope; > }; Mind the structure packing and alignment, placing a pointer in the middle of a section of bools is going to create wasteful holes in the data structure. > @@ -130,6 +131,9 @@ struct vfio_regions { > #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \ > (!list_empty(&iommu->domain_list)) > > +#define IS_DOMAIN_IN_CONTAINER(iommu) ((iommu->external_domain) || \ > + (!list_empty(&iommu->domain_list))) > + > #define DIRTY_BITMAP_BYTES(n) (ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE) > > /* > @@ -1959,6 +1963,12 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, > } > } > > + /* Nesting type container can include only one group */ > + if (iommu->nesting && IS_DOMAIN_IN_CONTAINER(iommu)) { > + mutex_unlock(&iommu->lock); > + return -EINVAL; > + } > + > group = kzalloc(sizeof(*group), GFP_KERNEL); > domain = kzalloc(sizeof(*domain), GFP_KERNEL); > if (!group || !domain) { > @@ -2029,6 +2039,36 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, > if (ret) > goto out_domain; > > + /* Nesting cap info is available only after attaching */ > + if (iommu->nesting) { > + struct iommu_nesting_info tmp; > + struct iommu_nesting_info *info; > + > + /* First get the size of vendor specific nesting info */ > + ret = iommu_domain_get_attr(domain->domain, > + DOMAIN_ATTR_NESTING, > + &tmp); > + if (ret) > + goto out_detach; > + > + info = kzalloc(tmp.size, GFP_KERNEL); > + if (!info) { > + ret = -ENOMEM; > + goto out_detach; > + } > + > + /* Now get the nesting info */ > + info->size = tmp.size; > + ret = iommu_domain_get_attr(domain->domain, > + DOMAIN_ATTR_NESTING, > + info); > + if (ret) { > + kfree(info); > + goto out_detach; > + } > + iommu->nesting_info = info; > + } > + > /* Get aperture info */ > iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, &geo); > > @@ -2138,6 +2178,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, > return 0; > > out_detach: > + kfree(iommu->nesting_info); This looks prone to a use-after-free. > vfio_iommu_detach_group(domain, group); > out_domain: > iommu_domain_free(domain->domain); > @@ -2338,6 +2379,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, > vfio_iommu_unmap_unpin_all(iommu); > else > vfio_iommu_unmap_unpin_reaccount(iommu); > + > + kfree(iommu->nesting_info); As does this. Set to NULL since get_info tests the pointer before trying to use it. > } > iommu_domain_free(domain->domain); > list_del(&domain->next); > @@ -2546,6 +2589,30 @@ static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu, > return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig)); > } > > +static int vfio_iommu_info_add_nesting_cap(struct vfio_iommu *iommu, > + struct vfio_info_cap *caps) > +{ > + struct vfio_info_cap_header *header; > + struct vfio_iommu_type1_info_cap_nesting *nesting_cap; > + size_t size; > + > + size = sizeof(*nesting_cap) + iommu->nesting_info->size; > + > + header = vfio_info_cap_add(caps, size, > + VFIO_IOMMU_TYPE1_INFO_CAP_NESTING, 1); > + if (IS_ERR(header)) > + return PTR_ERR(header); > + > + nesting_cap = container_of(header, > + struct vfio_iommu_type1_info_cap_nesting, > + header); > + > + memcpy(&nesting_cap->info, iommu->nesting_info, > + iommu->nesting_info->size); > + > + return 0; > +} > + > static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, > unsigned long arg) > { > @@ -2586,6 +2653,12 @@ static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, > if (ret) > return ret; > > + if (iommu->nesting_info) { > + ret = vfio_iommu_info_add_nesting_cap(iommu, &caps); > + if (ret) > + return ret; > + } > + > if (caps.size) { > info.flags |= VFIO_IOMMU_INFO_CAPS; > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index eca66926..f1f39e1 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -14,6 +14,7 @@ > > #include > #include > +#include Why? We're not directly referencing any IOMMU UAPI structures here. > > #define VFIO_API_VERSION 0 > > @@ -1039,6 +1040,14 @@ struct vfio_iommu_type1_info_cap_migration { > __u64 max_dirty_bitmap_size; /* in bytes */ > }; > > +#define VFIO_IOMMU_TYPE1_INFO_CAP_NESTING 3 > + > +struct vfio_iommu_type1_info_cap_nesting { > + struct vfio_info_cap_header header; > + __u32 flags; I think there's an alignment issue here for a uapi. The header field is 8-bytes total and info[] should start at an 8-byte alignment to allow data[] within info to have 8-byte alignment. This could lead to the structure having a compiler dependent size and offsets. We should add a 4-byte reserved field here to resolve. > + __u8 info[]; > +}; This should have a lot more description around it, a user could not infer that info[] is including a struct iommu_nesting_info from the information provided here. Thanks, Alex > + > #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) > > /**