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=-13.8 required=3.0 tests=BAYES_00, 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 91F85C433E0 for ; Tue, 12 Jan 2021 06:51:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4B95D22AAF for ; Tue, 12 Jan 2021 06:51:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391015AbhALGv1 (ORCPT ); Tue, 12 Jan 2021 01:51:27 -0500 Received: from foss.arm.com ([217.140.110.172]:40738 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389829AbhALGv0 (ORCPT ); Tue, 12 Jan 2021 01:51:26 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 38ADB13A1 for ; Mon, 11 Jan 2021 22:50:41 -0800 (PST) Received: from mail-pl1-f180.google.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 265853FA50 for ; Mon, 11 Jan 2021 22:50:41 -0800 (PST) Received: by mail-pl1-f180.google.com with SMTP id x18so890925pln.6 for ; Mon, 11 Jan 2021 22:50:41 -0800 (PST) X-Gm-Message-State: AOAM533nXKEb2dqoKkCXfT5GjYVlxGKcad4JObryTmn41mAkalrDXZHj uzaYeUhADPa2zy64mRSKQXzmWV0j+lvHnDx0tuQ= X-Google-Smtp-Source: ABdhPJxkM7Gy++KOxgg+Vg4KylRwV8QFQOGVeqrZZyEU2DDcq/JYCbjcYhWtGT34jkE/Co1DvCz6R7vLIIXujaJ2Oe4= X-Received: by 2002:a17:902:ee0b:b029:dc:1aa4:1123 with SMTP id z11-20020a170902ee0bb02900dc1aa41123mr3819896plb.18.1610434240490; Mon, 11 Jan 2021 22:50:40 -0800 (PST) MIME-Version: 1.0 References: <1599734733-6431-1-git-send-email-yi.l.liu@intel.com> <1599734733-6431-3-git-send-email-yi.l.liu@intel.com> In-Reply-To: <1599734733-6431-3-git-send-email-yi.l.liu@intel.com> From: Vivek Gautam Date: Tue, 12 Jan 2021 12:20:29 +0530 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v7 02/16] iommu/smmu: Report empty domain nesting info To: Liu Yi L Cc: alex.williamson@redhat.com, eric.auger@redhat.com, baolu.lu@linux.intel.com, Joerg Roedel , Jean-Philippe Brucker , kevin.tian@intel.com, ashok.raj@intel.com, kvm@vger.kernel.org, stefanha@gmail.com, jun.j.tian@intel.com, "list@263.net:IOMMU DRIVERS , Joerg Roedel ," , yi.y.sun@intel.com, Robin Murphy , Will Deacon , jasowang@redhat.com, hao.wu@intel.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Yi, On Thu, Sep 10, 2020 at 4:13 PM Liu Yi L wrote: > > This patch is added as instead of returning a boolean for DOMAIN_ATTR_NESTING, > iommu_domain_get_attr() should return an iommu_nesting_info handle. For > now, return an empty nesting info struct for now as true nesting is not > yet supported by the SMMUs. > > Cc: Will Deacon > Cc: Robin Murphy > Cc: Eric Auger > Cc: Jean-Philippe Brucker > Suggested-by: Jean-Philippe Brucker > Signed-off-by: Liu Yi L > Signed-off-by: Jacob Pan > Reviewed-by: Eric Auger > --- > v5 -> v6: > *) add review-by from Eric Auger. > > v4 -> v5: > *) address comments from Eric Auger. > --- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 29 +++++++++++++++++++++++++++-- > drivers/iommu/arm/arm-smmu/arm-smmu.c | 29 +++++++++++++++++++++++++++-- > 2 files changed, 54 insertions(+), 4 deletions(-) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 7196207..016e2e5 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -3019,6 +3019,32 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev) > return group; > } > > +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain *smmu_domain, > + void *data) > +{ > + struct iommu_nesting_info *info = (struct iommu_nesting_info *)data; > + unsigned int size; > + > + if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED) > + return -ENODEV; > + > + size = sizeof(struct iommu_nesting_info); > + > + /* > + * if provided buffer size is smaller than expected, should > + * return 0 and also the expected buffer size to caller. > + */ > + if (info->argsz < size) { > + info->argsz = size; > + return 0; > + } > + > + /* report an empty iommu_nesting_info for now */ > + memset(info, 0x0, size); > + info->argsz = size; > + return 0; > +} > + > static int arm_smmu_domain_get_attr(struct iommu_domain *domain, > enum iommu_attr attr, void *data) > { > @@ -3028,8 +3054,7 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain, > case IOMMU_DOMAIN_UNMANAGED: > switch (attr) { > case DOMAIN_ATTR_NESTING: > - *(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED); > - return 0; > + return arm_smmu_domain_nesting_info(smmu_domain, data); Thanks for the patch. This would unnecessarily overflow 'data' for any caller that's expecting only an int data. Dump from one such issue that I was seeing when testing this change along with local kvmtool changes is pasted below [1]. I could get around with the issue by adding another (iommu_attr) - DOMAIN_ATTR_NESTING_INFO that returns (iommu_nesting_info). Thanks & regards Vivek [1]-------------- [ 811.756516] vfio-pci 0000:08:00.1: vfio_ecap_init: hiding ecap 0x1b@0x108 [ 811.756516] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: vfio_pci_open+0x644/0x648 [ 811.756516] CPU: 0 PID: 175 Comm: lkvm-cleanup-ne Not tainted 5.10.0-rc5-00096-gf015061e14cf #43 [ 811.756516] Call trace: [ 811.756516] dump_backtrace+0x0/0x1b0 [ 811.756516] show_stack+0x18/0x68 [ 811.756516] dump_stack+0xd8/0x134 [ 811.756516] panic+0x174/0x33c [ 811.756516] __stack_chk_fail+0x3c/0x40 [ 811.756516] vfio_pci_open+0x644/0x648 [ 811.756516] vfio_group_fops_unl_ioctl+0x4bc/0x648 [ 811.756516] 0x0 [ 811.756516] SMP: stopping secondary CPUs [ 811.756597] Kernel Offset: disabled [ 811.756597] CPU features: 0x0040006,6a00aa38 [ 811.756602] Memory Limit: none [ 811.768497] ---[ end Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: vfio_pci_open+0x644/0x648 ] -------------