From patchwork Thu Apr 25 09:15:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cornelia Huck X-Patchwork-Id: 10916343 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9C287161F for ; Thu, 25 Apr 2019 09:16:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8E0DD28BB7 for ; Thu, 25 Apr 2019 09:16:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 829FE28C4D; Thu, 25 Apr 2019 09:16:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 173D628BB7 for ; Thu, 25 Apr 2019 09:16:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727563AbfDYJQJ (ORCPT ); Thu, 25 Apr 2019 05:16:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43216 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727055AbfDYJQI (ORCPT ); Thu, 25 Apr 2019 05:16:08 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 08F143092647; Thu, 25 Apr 2019 09:16:08 +0000 (UTC) Received: from localhost (dhcp-192-187.str.redhat.com [10.33.192.187]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A5BDB5C28D; Thu, 25 Apr 2019 09:16:07 +0000 (UTC) From: Cornelia Huck To: Martin Schwidefsky , Heiko Carstens Cc: Farhan Ali , Eric Farman , Halil Pasic , linux-s390@vger.kernel.org, kvm@vger.kernel.org, Cornelia Huck Subject: [PULL 3/9] vfio-ccw: protect the I/O region Date: Thu, 25 Apr 2019 11:15:53 +0200 Message-Id: <20190425091559.15490-4-cohuck@redhat.com> In-Reply-To: <20190425091559.15490-1-cohuck@redhat.com> References: <20190425091559.15490-1-cohuck@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Thu, 25 Apr 2019 09:16:08 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Introduce a mutex to disallow concurrent reads or writes to the I/O region. This makes sure that the data the kernel or user space see is always consistent. The same mutex will be used to protect the async region as well. Reviewed-by: Eric Farman Signed-off-by: Cornelia Huck --- drivers/s390/cio/vfio_ccw_drv.c | 3 +++ drivers/s390/cio/vfio_ccw_ops.c | 28 +++++++++++++++++++--------- drivers/s390/cio/vfio_ccw_private.h | 2 ++ 3 files changed, 24 insertions(+), 9 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index 0b3b9de45c60..5ea0da1dd954 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -84,7 +84,9 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) if (is_final) cp_free(&private->cp); } + mutex_lock(&private->io_mutex); memcpy(private->io_region->irb_area, irb, sizeof(*irb)); + mutex_unlock(&private->io_mutex); if (private->io_trigger) eventfd_signal(private->io_trigger, 1); @@ -129,6 +131,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) private->sch = sch; dev_set_drvdata(&sch->dev, private); + mutex_init(&private->io_mutex); spin_lock_irq(sch->lock); private->state = VFIO_CCW_STATE_NOT_OPER; diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c index 3fdcc6dfe0bf..025c8a832bc8 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -169,16 +169,20 @@ static ssize_t vfio_ccw_mdev_read(struct mdev_device *mdev, { struct vfio_ccw_private *private; struct ccw_io_region *region; + int ret; if (*ppos + count > sizeof(*region)) return -EINVAL; private = dev_get_drvdata(mdev_parent_dev(mdev)); + mutex_lock(&private->io_mutex); region = private->io_region; if (copy_to_user(buf, (void *)region + *ppos, count)) - return -EFAULT; - - return count; + ret = -EFAULT; + else + ret = count; + mutex_unlock(&private->io_mutex); + return ret; } static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, @@ -188,23 +192,29 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, { struct vfio_ccw_private *private; struct ccw_io_region *region; + int ret; if (*ppos + count > sizeof(*region)) return -EINVAL; private = dev_get_drvdata(mdev_parent_dev(mdev)); + if (!mutex_trylock(&private->io_mutex)) + return -EAGAIN; region = private->io_region; - if (copy_from_user((void *)region + *ppos, buf, count)) - return -EFAULT; + if (copy_from_user((void *)region + *ppos, buf, count)) { + ret = -EFAULT; + goto out_unlock; + } vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ); - if (region->ret_code != 0) { + if (region->ret_code != 0) private->state = VFIO_CCW_STATE_IDLE; - return region->ret_code; - } + ret = (region->ret_code != 0) ? region->ret_code : count; - return count; +out_unlock: + mutex_unlock(&private->io_mutex); + return ret; } static int vfio_ccw_mdev_get_device_info(struct vfio_device_info *info) diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h index 50c52efb4fcb..32173cbd838d 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -28,6 +28,7 @@ * @mdev: pointer to the mediated device * @nb: notifier for vfio events * @io_region: MMIO region to input/output I/O arguments/results + * @io_mutex: protect against concurrent update of I/O regions * @cp: channel program for the current I/O operation * @irb: irb info received from interrupt * @scsw: scsw info @@ -42,6 +43,7 @@ struct vfio_ccw_private { struct mdev_device *mdev; struct notifier_block nb; struct ccw_io_region *io_region; + struct mutex io_mutex; struct channel_program cp; struct irb irb;