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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 CF11AC433E2 for ; Thu, 17 Sep 2020 12:15:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8671D206B5 for ; Thu, 17 Sep 2020 12:15:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Msg5PtmI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726807AbgIQMPc (ORCPT ); Thu, 17 Sep 2020 08:15:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:43287 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726819AbgIQMPW (ORCPT ); Thu, 17 Sep 2020 08:15:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600344901; 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=EP9WEZ46YHNtdW0HPtYLcHBIcBFzJYSz8/bOvDElUN4=; b=Msg5PtmIpowcwmZBGPSYoAYdwcPKiDuyUtKFG0olR/FxerbUI2Lh/g3wlHuJqMZXPpFCad 8vI3bjUuqgdlPC8KPt3iLT7641adSJcCKJ4pXWzPOVwIwuoEAEF+vhPgtfNdYcaDKcgqCY l8Az6VHS1wcXl5Y/eUZ9BGzpSoOHaeo= 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-239-5Tm4eSR-P1qnKjmrHrE4Rw-1; Thu, 17 Sep 2020 08:14:57 -0400 X-MC-Unique: 5Tm4eSR-P1qnKjmrHrE4Rw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 140D41084C81; Thu, 17 Sep 2020 12:14:55 +0000 (UTC) Received: from gondolin (ovpn-113-19.ams2.redhat.com [10.36.113.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3D24B75261; Thu, 17 Sep 2020 12:14:45 +0000 (UTC) Date: Thu, 17 Sep 2020 14:14:42 +0200 From: Cornelia Huck To: Tony Krowiak Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, fiuczy@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, kernel test robot Subject: Re: [PATCH v10 04/16] s390/zcrypt: driver callback to indicate resource in use Message-ID: <20200917141442.6e531799.cohuck@redhat.com> In-Reply-To: References: <20200821195616.13554-1-akrowiak@linux.ibm.com> <20200821195616.13554-5-akrowiak@linux.ibm.com> <20200914172947.533ddf56.cohuck@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 15 Sep 2020 15:32:35 -0400 Tony Krowiak wrote: > On 9/14/20 11:29 AM, Cornelia Huck wrote: > > On Fri, 21 Aug 2020 15:56:04 -0400 > > Tony Krowiak wrote: > > > >> Introduces a new driver callback to prevent a root user from unbinding > >> an AP queue from its device driver if the queue is in use. The intent of > >> this callback is to provide a driver with the means to prevent a root user > >> from inadvertently taking a queue away from a matrix mdev and giving it to > >> the host while it is assigned to the matrix mdev. The callback will > >> be invoked whenever a change to the AP bus's sysfs apmask or aqmask > >> attributes would result in one or more AP queues being removed from its > >> driver. If the callback responds in the affirmative for any driver > >> queried, the change to the apmask or aqmask will be rejected with a device > >> in use error. > >> > >> For this patch, only non-default drivers will be queried. Currently, > >> there is only one non-default driver, the vfio_ap device driver. The > >> vfio_ap device driver facilitates pass-through of an AP queue to a > >> guest. The idea here is that a guest may be administered by a different > >> sysadmin than the host and we don't want AP resources to unexpectedly > >> disappear from a guest's AP configuration (i.e., adapters, domains and > >> control domains assigned to the matrix mdev). This will enforce the proper > >> procedure for removing AP resources intended for guest usage which is to > >> first unassign them from the matrix mdev, then unbind them from the > >> vfio_ap device driver. > >> > >> Signed-off-by: Tony Krowiak > >> Reported-by: kernel test robot > > This looks a bit odd... > > I've removed all of those. These kernel test robot errors were flagged > in the last series. The review comments from the robot suggested > the reported-by, but I assume that was for patches intended to > fix those errors, so I am removing these as per Christian's comments. Yes, I think the Reported-by: mostly makes sense if you include a patch to fix something on top. > > > > >> --- > >> drivers/s390/crypto/ap_bus.c | 148 ++++++++++++++++++++++++++++++++--- > >> drivers/s390/crypto/ap_bus.h | 4 + > >> 2 files changed, 142 insertions(+), 10 deletions(-) > >> > > (...) > > > >> @@ -1107,12 +1118,70 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf) > >> return rc; > >> } > >> > >> +static int __verify_card_reservations(struct device_driver *drv, void *data) > >> +{ > >> + int rc = 0; > >> + struct ap_driver *ap_drv = to_ap_drv(drv); > >> + unsigned long *newapm = (unsigned long *)data; > >> + > >> + /* > >> + * No need to verify whether the driver is using the queues if it is the > >> + * default driver. > >> + */ > >> + if (ap_drv->flags & AP_DRIVER_FLAG_DEFAULT) > >> + return 0; > >> + > >> + /* The non-default driver's module must be loaded */ > >> + if (!try_module_get(drv->owner)) > >> + return 0; > >> + > >> + if (ap_drv->in_use) > >> + if (ap_drv->in_use(newapm, ap_perms.aqm)) > >> + rc = -EADDRINUSE; > > ISTR that Christian suggested -EBUSY in a past revision of this series? > > I think that would be more appropriate. > > I went back and looked and sure enough, he did recommend that. > You have a great memory! I didn't respond to that comment, so I > must have missed it at the time. > > I personally prefer EADDRINUSE because I think it is more indicative > of the reason an AP resource can not be assigned back to the host > drivers is because it is in use by a guest or, at the very least, reserved > for use by a guest (i.e., assigned to an mdev). To say it is busy implies > that the device is busy performing encryption services which may or > may not be true at a given moment. Even if so, that is not the reason > for refusing to allow reassignment of the device. I have a different understanding of these error codes: EADDRINUSE is something used in the networking context when an actual address is already used elsewhere. EBUSY is more of a generic error that indicates that a certain resource is not free to perform the requested operation; it does not necessarily mean that the resource is currently actively doing something. Kind of when you get EBUSY when trying to eject something another program holds a reference on: that other program might not actually be doing anything, but it potentially could.