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Wed, 22 Jul 2020 22:46:16 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06MMYHBg065331; Wed, 22 Jul 2020 22:46:15 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 32ewejb2an-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 22 Jul 2020 22:46:15 +0000 Received: from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 06MMk0p3015871; Wed, 22 Jul 2020 22:46:00 GMT Received: from [10.39.211.22] (/10.39.211.22) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 22 Jul 2020 15:46:00 -0700 Subject: Re: [PATCH v2 01/11] xen/manage: keep track of the on-going suspend mode To: Anchal Agarwal , Stefano Stabellini Cc: 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, 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: <20200702182136.GA3511@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> <50298859-0d0e-6eb0-029b-30df2a4ecd63@oracle.com> <20200715204943.GB17938@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> <0ca3c501-e69a-d2c9-a24c-f83afd4bdb8c@oracle.com> <20200717191009.GA3387@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> <5464f384-d4b4-73f0-d39e-60ba9800d804@oracle.com> <20200721000348.GA19610@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> <408d3ce9-2510-2950-d28d-fdfe8ee41a54@oracle.com> <20200722180229.GA32316@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> From: Boris Ostrovsky Autocrypt: addr=boris.ostrovsky@oracle.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200722180229.GA32316@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9690 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 suspectscore=0 mlxscore=0 spamscore=0 mlxlogscore=999 adultscore=0 bulkscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007220141 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9690 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 suspectscore=0 bulkscore=0 mlxscore=0 mlxlogscore=999 impostorscore=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 spamscore=0 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007220141 X-Rspamd-Queue-Id: 2AAD3184F4E6C X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 7/22/20 2:02 PM, Anchal Agarwal wrote: > On Tue, Jul 21, 2020 at 05:18:34PM -0700, Stefano Stabellini wrote: >> >> >>> If you are not sure what the effects are (or sure that it won't work)= on >>> ARM then I'd add IS_ENABLED(CONFIG_X86) check, i.e. >>> >>> >>> if (!IS_ENABLED(CONFIG_X86) || !xen_hvm_domain()) >>> return -ENODEV; >> That is a good principle to have and thanks for suggesting it. However= , >> in this specific case there is nothing in this patch that doesn't work= >> on ARM. From an ARM perspective I think we should enable it and >> &xen_pm_notifier_block should be registered. >> > This question is for Boris, I think you we decided to get rid of the no= tifier > in V3 as all we need to check is SHUTDOWN_SUSPEND state which sounds p= lausible > to me. So this check may go away. It may still be needed for sycore_ops= > callbacks registration. If this check is going away then I guess there is nothing to do here. My concern isn't about this particular notifier but rather whether this feature may affect existing functionality (ARM and PVH dom0). If Stefano feels this should be fine for ARM then so be it. -boris >> Given that all guests are HVM guests on ARM, it should work fine as is= =2E >> >> >> I gave a quick look at the rest of the series and everything looks fin= e >> to me from an ARM perspective. I cannot imaging that the new freeze, >> thaw, and restore callbacks for net and block are going to cause any >> trouble on ARM. The two main x86-specific functions are >> xen_syscore_suspend/resume and they look trivial to implement on ARM (= in >> the sense that they are likely going to look exactly the same.) >> > Yes but for now since things are not tested I will put this > !IS_ENABLED(CONFIG_X86) on syscore_ops calls registration part just to = be safe > and not break anything. >> One question for Anchal: what's going to happen if you trigger a >> hibernation, you have the new callbacks, but you are missing >> xen_syscore_suspend/resume? >> >> Is it any worse than not having the new freeze, thaw and restore >> callbacks at all and try to do a hibernation? > If callbacks are not there, I don't expect hibernation to work correctl= y. > These callbacks takes care of xen primitives like shared_info_page, > grant table, sched clock, runstate time which are important to save the= correct > state of the guest and bring it back up. Other patches in the series, a= dds all > the logic to these syscore callbacks. Freeze/thaw/restore are just ther= e for at driver > level. > > Thanks, > Anchal