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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 1723CC04AB4 for ; Tue, 14 May 2019 09:04:03 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C9DD420862 for ; Tue, 14 May 2019 09:04:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C9DD420862 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:43428 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hQTLu-0001Zk-1R for qemu-devel@archiver.kernel.org; Tue, 14 May 2019 05:04:02 -0400 Received: from eggs.gnu.org ([209.51.188.92]:56080) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hQTIT-00084X-ID for qemu-devel@nongnu.org; Tue, 14 May 2019 05:00:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hQTIO-0007Vt-HO for qemu-devel@nongnu.org; Tue, 14 May 2019 05:00:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54642) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hQTIO-0007V8-8I; Tue, 14 May 2019 05:00:24 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4EE273004153; Tue, 14 May 2019 09:00:23 +0000 (UTC) Received: from [10.36.117.118] (ovpn-117-118.ams2.redhat.com [10.36.117.118]) by smtp.corp.redhat.com (Postfix) with ESMTP id 81B4551DF1; Tue, 14 May 2019 09:00:17 +0000 (UTC) To: Christian Borntraeger , Cornelia Huck References: <1556749903-19221-1-git-send-email-walling@linux.ibm.com> <09293a1c-d000-83a8-46b8-b97ad4fa9774@de.ibm.com> <56e3ace1-6e48-0e20-47d5-b07ac6dfcf31@redhat.com> <20190513134637.3d8bb275.cohuck@redhat.com> <898144e3-615e-5074-fb68-bf9995c64609@de.ibm.com> <155d2ca3-6a48-c99a-fe42-dca8e3fd4344@redhat.com> <066c7470-94a3-a922-9a12-1ca42e474c51@de.ibm.com> <1a3dcb16-8c6f-214c-843d-6dca6a24801e@redhat.com> <9a9e9c58-d991-369f-a577-b70581efc75b@de.ibm.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <3cacee74-92f8-c63a-1aa4-7a169714d70c@redhat.com> Date: Tue, 14 May 2019 11:00:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <9a9e9c58-d991-369f-a577-b70581efc75b@de.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Tue, 14 May 2019 09:00:23 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v4] s390: diagnose 318 info reset and migration support X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Collin Walling , mst@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, qemu-s390x@nongnu.org, pbonzini@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 14.05.19 10:56, Christian Borntraeger wrote: > > > On 14.05.19 10:50, David Hildenbrand wrote: >> On 14.05.19 10:37, Christian Borntraeger wrote: >>> >>> >>> On 14.05.19 09:28, David Hildenbrand wrote: >>>>>>> But that can be tested using the runability information if I am not wrong. >>>>>> >>>>>> You mean the cpu level information, right? >>>> >>>> Yes, query-cpu-definition includes for each model runability information >>>> via "unavailable-features" (valid under the started QEMU machine). >>>> >>>>>> >>>>>>> >>>>>>>> and others that we have today. >>>>>>>> >>>>>>>> So yes, I think this would be acceptable. >>>>>>> >>>>>>> I guess it is acceptable yes. I doubt anybody uses that many CPUs in >>>>>>> production either way. But you never know. >>>>>> >>>>>> I think that using that many cpus is a more uncommon setup, but I still >>>>>> think that having to wait for actual failure >>>>> >>>>> That can happen all the time today. You can easily say z14 in the xml when >>>>> on a zEC12. Only at startup you get the error. The question is really: >>>> >>>> "-smp 248 -cpu host" will no longer work, while e.g. "-smp 248 -cpu z12" >>>> will work. Actually, even "-smp 248" will no longer work on affected >>>> machines. >>>> >>>> That is why wonder if it is better to disable the feature and print a >>>> warning. Similar to CMMA, where want want to tolerate when CMMA is not >>>> possible in the current environment (huge pages). >>>> >>>> "Diag318 will not be enabled because it is not compatible with more than >>>> 240 CPUs". >>>> >>>> However, I still think that implementing support for more than one SCLP >>>> response page is the best solution. Guests will need adaptions for > 240 >>>> CPUs with Diag318, but who cares? Existing setups will continue to work. >>>> >>>> Implementing that SCLP thingy will avoid any warnings and any errors. It >>>> just works from the QEMU perspective. >>>> >>>> Is implementing this realistic? >>> >>> Yes it is but it will take time. I will try to get this rolling. To make >>> progress on the diag318 thing, can we error on startup now and simply >>> remove that check when when have implemented a larger sccb? If we would >>> now do all kinds of "change the max number games" would be harder to "fix". >> >> >> Another idea for temporary handling: Simply only indicate 240 CPUs to >> the guest if the response does not fit into a page. Once we have that >> SCLP thingy, this will be fixed. Guest migration back and forth should >> work, as the VCPUs are fully functional (and initially always stopped), >> the guest will simply not be able to detect them via SCLP when booting >> up, and therefore not use them. > > Yes, that looks like a good temporary solution. In fact if the guest relies > on simply probing it could even make use of the additional CPUs. Its just > the sclp response that is limited to 240 (or make it 247?) I think the limiting factor was more than a single CPU, but I don't recall. We can do the math again and come up with the right number. -- Thanks, David / dhildenb