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Sun, 13 Sep 2020 15:43:56 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 08DFPuQU088545; Sun, 13 Sep 2020 15:43:56 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 33h7wjsx4k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 13 Sep 2020 15:43:56 +0000 Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 08DFhabS027483; Sun, 13 Sep 2020 15:43:36 GMT Received: from [10.74.86.192] (/10.74.86.192) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 13 Sep 2020 15:43:36 +0000 Subject: Re: [PATCH v3 01/11] xen/manage: keep track of the on-going suspend mode To: Anchal Agarwal , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, jgross@suse.com, linux-pm@vger.kernel.org, linux-mm@kvack.org, kamatam@amazon.com, sstabellini@kernel.org, konrad.wilk@oracle.com, roger.pau@citrix.com, axboe@kernel.dk, davem@davemloft.net, rjw@rjwysocki.net, len.brown@intel.com, pavel@ucw.cz, peterz@infradead.org, eduval@amazon.com, sblbir@amazon.com, xen-devel@lists.xenproject.org, vkuznets@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dwmw@amazon.co.uk, benh@kernel.crashing.org References: <9b970e12491107afda0c1d4a6f154b52d90346ac.1598042152.git.anchalag@amazon.com> From: boris.ostrovsky@oracle.com Organization: Oracle Corporation Message-ID: <4b2bbc8b-7817-271a-4ff0-5ee5df956049@oracle.com> Date: Sun, 13 Sep 2020 11:43:30 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.2.1 MIME-Version: 1.0 In-Reply-To: <9b970e12491107afda0c1d4a6f154b52d90346ac.1598042152.git.anchalag@amazon.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9743 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 adultscore=0 bulkscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009130140 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9743 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 adultscore=0 phishscore=0 spamscore=0 clxscore=1015 mlxscore=0 impostorscore=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 mlxlogscore=999 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009130140 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/21/20 6:25 PM, Anchal Agarwal wrote: > From: Munehisa Kamata > > Guest hibernation is different from xen suspend/resume/live migration. > Xen save/restore does not use pm_ops as is needed by guest hibernation. > Hibernation in guest follows ACPI path and is guest inititated , the > hibernation image is saved within guest as compared to later modes > which are xen toolstack assisted and image creation/storage is in > control of hypervisor/host machine. > To differentiate between Xen suspend and PM hibernation, keep track > of the on-going suspend mode by mainly using a new API to keep track of > SHUTDOWN_SUSPEND state. > Introduce a simple function that keeps track of on-going suspend mode > so that PM hibernation code can behave differently according to the > current suspend mode. > Since Xen suspend doesn't have corresponding PM event, its main logic > is modfied to acquire pm_mutex. lock_system_sleep() is not taking this mutex. > > Though, accquirng pm_mutex is still right thing to do, we may > see deadlock if PM hibernation is interrupted by Xen suspend. > PM hibernation depends on xenwatch thread to process xenbus state > transactions, but the thread will sleep to wait pm_mutex which is > already held by PM hibernation context in the scenario. Xen shutdown > code may need some changes to avoid the issue. Is it Xen's shutdown or suspend code that needs to address this? (Or I may not understand what the problem is that you are describing) > > + > +static int xen_pm_notifier(struct notifier_block *notifier, > + unsigned long pm_event, void *unused) > +{ > + int ret; > + > + switch (pm_event) { > + case PM_SUSPEND_PREPARE: > + case PM_HIBERNATION_PREPARE: > + /* Guest hibernation is not supported for aarch64 currently*/ > + if (IS_ENABLED(CONFIG_ARM64)) { > + ret = NOTIFY_BAD; > + break; > + } Indentation. > + case PM_RESTORE_PREPARE: > + case PM_POST_SUSPEND: > + case PM_POST_HIBERNATION: > + case PM_POST_RESTORE: > + default: > + ret = NOTIFY_OK; > + } > + return ret; > +}; This whole routine now is if (IS_ENABLED(CONFIG_ARM64)) return NOTIFY_BAD; return NOTIFY_OK; isn't it? > + > +static struct notifier_block xen_pm_notifier_block = { > + .notifier_call = xen_pm_notifier > +}; > + > +static int xen_setup_pm_notifier(void) > +{ > + if (!xen_hvm_domain() || xen_initial_domain()) > + return -ENODEV; I don't think this works anymore. In the past your notifier would set suspend_mode (or something) but now it really doesn't do anything except reports an error in some (ARM) cases. So I think you should move this check into the notifier. (And BTW I still think PM_SUSPEND_PREPARE should return an error too. The fact that we are using "suspend" in xen routine names is irrelevant) -boris > + return register_pm_notifier(&xen_pm_notifier_block); > +} > +