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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 676E0C04EB8 for ; Wed, 12 Dec 2018 14:24:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2EBA420849 for ; Wed, 12 Dec 2018 14:24:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2EBA420849 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727694AbeLLOYd (ORCPT ); Wed, 12 Dec 2018 09:24:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39196 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726249AbeLLOYc (ORCPT ); Wed, 12 Dec 2018 09:24:32 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id 6BBDC3DE2C; Wed, 12 Dec 2018 14:24:32 +0000 (UTC) Received: from redhat.com (ovpn-122-106.rdu2.redhat.com [10.10.122.106]) by smtp.corp.redhat.com (Postfix) with SMTP id 93CF8608C6; Wed, 12 Dec 2018 14:24:31 +0000 (UTC) Date: Wed, 12 Dec 2018 09:24:31 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Tonghao Zhang Subject: Re: [PATCH net V2 3/4] Revert "net: vhost: lock the vqs one by one" Message-ID: <20181212092102-mutt-send-email-mst@kernel.org> References: <20181212100819.21295-1-jasowang@redhat.com> <20181212100819.21295-4-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181212100819.21295-4-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 12 Dec 2018 14:24:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 12, 2018 at 06:08:18PM +0800, Jason Wang wrote: > This reverts commit 78139c94dc8c96a478e67dab3bee84dc6eccb5fd. We don't > protect device IOTLB with vq mutex, which will lead e.g use after free > for device IOTLB entries. And since we've switched to use > mutex_trylock() in previous patch, it's safe to revert it without > having deadlock. > > Fixes: commit 78139c94dc8c ("net: vhost: lock the vqs one by one") > Cc: Tonghao Zhang > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin I'd try to put this in 4.20 if we can and it's needed for -stable I think. Also looks like we should allow iotlb entries per vq to improve locking. What do you think? > --- > drivers/vhost/vhost.c | 21 +++++++++++++++++---- > 1 file changed, 17 insertions(+), 4 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 5915f240275a..55e5aa662ad5 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -295,11 +295,8 @@ static void vhost_vq_meta_reset(struct vhost_dev *d) > { > int i; > > - for (i = 0; i < d->nvqs; ++i) { > - mutex_lock(&d->vqs[i]->mutex); > + for (i = 0; i < d->nvqs; ++i) > __vhost_vq_meta_reset(d->vqs[i]); > - mutex_unlock(&d->vqs[i]->mutex); > - } > } > > static void vhost_vq_reset(struct vhost_dev *dev, > @@ -895,6 +892,20 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq, > #define vhost_get_used(vq, x, ptr) \ > vhost_get_user(vq, x, ptr, VHOST_ADDR_USED) > > +static void vhost_dev_lock_vqs(struct vhost_dev *d) > +{ > + int i = 0; > + for (i = 0; i < d->nvqs; ++i) > + mutex_lock_nested(&d->vqs[i]->mutex, i); > +} > + > +static void vhost_dev_unlock_vqs(struct vhost_dev *d) > +{ > + int i = 0; > + for (i = 0; i < d->nvqs; ++i) > + mutex_unlock(&d->vqs[i]->mutex); > +} > + > static int vhost_new_umem_range(struct vhost_umem *umem, > u64 start, u64 size, u64 end, > u64 userspace_addr, int perm) > @@ -976,6 +987,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, > int ret = 0; > > mutex_lock(&dev->mutex); > + vhost_dev_lock_vqs(dev); > switch (msg->type) { > case VHOST_IOTLB_UPDATE: > if (!dev->iotlb) { > @@ -1009,6 +1021,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, > break; > } > > + vhost_dev_unlock_vqs(dev); > mutex_unlock(&dev->mutex); > > return ret; > -- > 2.17.1