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=-3.9 required=3.0 tests=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 autolearn=no 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 C7A17C2BA19 for ; Tue, 14 Apr 2020 12:59:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9CC642084D for ; Tue, 14 Apr 2020 12:59:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VnNj778c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502463AbgDNM7J (ORCPT ); Tue, 14 Apr 2020 08:59:09 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:47554 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2502442AbgDNM7H (ORCPT ); Tue, 14 Apr 2020 08:59:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586869145; 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=0fdJexKCJPjvfrLIsyDcvHn2Ex4ChlT7CSP78FqF/p0=; b=VnNj778cGKUlivICZIfMFaM8HVcvPy1DHC7xDzuPpnMRdUSsdcsZnQy/ViiTBwvNrpTXLP AkctvHSIZXm3mh+lMv+vPWSDyemCjyh8dXiRqn8SQsUYEj0LondzPmov3usGpnI3t6gZUV dd8FHLsKw043yc3WnaTYkQoehyXZ3zM= 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-310-vOXVWCNXO6iub9T6nt5_og-1; Tue, 14 Apr 2020 08:59:02 -0400 X-MC-Unique: vOXVWCNXO6iub9T6nt5_og-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1FD1E13F8; Tue, 14 Apr 2020 12:59:00 +0000 (UTC) Received: from gondolin (ovpn-113-32.ams2.redhat.com [10.36.113.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id DD8425C1B2; Tue, 14 Apr 2020 12:58:54 +0000 (UTC) Date: Tue, 14 Apr 2020 14:58:51 +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, pmorel@linux.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, jjherne@linux.ibm.com, fiuczy@linux.ibm.com Subject: Re: [PATCH v7 03/15] s390/zcrypt: driver callback to indicate resource in use Message-ID: <20200414145851.562867ae.cohuck@redhat.com> In-Reply-To: <20200407192015.19887-4-akrowiak@linux.ibm.com> References: <20200407192015.19887-1-akrowiak@linux.ibm.com> <20200407192015.19887-4-akrowiak@linux.ibm.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 10.5.11.16 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 7 Apr 2020 15:20:03 -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 guest and giving it to the > host while the guest is still using it. 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 manages AP queues passed through to one or more > guests and we don't want to unexpectedly take AP resources away from > guests which are most likely independently administered. > > Signed-off-by: Tony Krowiak > --- > drivers/s390/crypto/ap_bus.c | 144 +++++++++++++++++++++++++++++++++-- > drivers/s390/crypto/ap_bus.h | 4 + > 2 files changed, 142 insertions(+), 6 deletions(-) (...) > @@ -1196,12 +1202,75 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf) > return rc; > } > > +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; > + > + /* > + * If the reserved bits do not identify cards reserved for use by the > + * non-default driver, there is no need to verify the driver is using > + * the queues. I had to read that one several times... what about "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; Is that really needed? I would have thought that the driver core's klist usage would make sure that the callback would not be invoked for drivers that are not registered anymore. Or am I missing a window? > + > + if (ap_drv->in_use) > + if (ap_drv->in_use(newapm, ap_perms.aqm)) Can we log the offending apm somewhere, preferably with additional info that allows the admin to figure out why an error was returned? > + rc = -EADDRINUSE; > + > + module_put(drv->owner); > + > + return rc; > +} (Same comments for the other changes further along in this patch.)