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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 ([::1]:48322 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kBcVx-0004lT-8H for qemu-devel@archiver.kernel.org; Fri, 28 Aug 2020 07:25:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43590) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kBcVB-0004Lp-Ug for qemu-devel@nongnu.org; Fri, 28 Aug 2020 07:25:01 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:56030) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kBcV9-0002Zm-3P for qemu-devel@nongnu.org; Fri, 28 Aug 2020 07:25:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598613898; 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=g0MZ1wQnlJgDQdvHEfiN1K88BB+fmUAjPO0KY5xXV/0=; b=DlBMoeQYyuRMNtqb+/LY5rinWwhNO0+4mDg+iq+pCYgTxhdpUqcUW7NnDYBhZXp3XlECR6 g51fiOJCNu9qp8PXgrDn4BHdcc2rN5y/mEKGF+SNLJxGLXkrEeL9SlLDzcT9cdFZEbtb9v lIYoNPl9EAXeCc54qPD99hC2dbl1JQE= 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-176-tnNPU0dFMTebftKO56OfGA-1; Fri, 28 Aug 2020 07:24:53 -0400 X-MC-Unique: tnNPU0dFMTebftKO56OfGA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BF7DA10ABDCD; Fri, 28 Aug 2020 11:24:51 +0000 (UTC) Received: from localhost (unknown [10.43.2.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id 69EA21009AF8; Fri, 28 Aug 2020 11:24:37 +0000 (UTC) Date: Fri, 28 Aug 2020 13:24:36 +0200 From: Igor Mammedov To: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" Subject: Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode Message-ID: <20200828132436.63de9921@redhat.com> In-Reply-To: <20200828085803.GD224144@redhat.com> References: <159804762216.39954.15502128500494116468.stgit@naples-babu.amd.com> <20200826143849.59f6970b@redhat.com> <20200826125059.GN168515@redhat.com> <20200826153034.115126cb@redhat.com> <5c00dac9-5ea5-405c-93be-1ac903ddff62@amd.com> <20200826183331.GA3977@work-vm> <11489e5f-2285-ddb4-9c35-c9f522d603a0@amd.com> <20200827222110.1c2ee236@imammedo-mac> <20200828085803.GD224144@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=63.128.21.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/28 04:08:55 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.959, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "ehabkost@redhat.com" , "mst@redhat.com" , Michal Privoznik , "qemu-devel@nongnu.org" , "Dr. David Alan Gilbert" , Babu Moger , "pbonzini@redhat.com" , "rth@twiddle.net" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 28 Aug 2020 09:58:03 +0100 Daniel P. Berrang=C3=A9 wrote: > On Thu, Aug 27, 2020 at 10:21:10PM +0200, Igor Mammedov wrote: > > On Wed, 26 Aug 2020 13:45:51 -0500 > > Babu Moger wrote: > > =20 > > >=20 > > > =20 > > > > -----Original Message----- > > > > From: Dr. David Alan Gilbert > > > > Sent: Wednesday, August 26, 2020 1:34 PM > > > > To: Moger, Babu > > > > Cc: Igor Mammedov ; Daniel P. Berrang=C3=A9 > > > > ; ehabkost@redhat.com; mst@redhat.com; Michal > > > > Privoznik ; qemu-devel@nongnu.org; > > > > pbonzini@redhat.com; rth@twiddle.net > > > > Subject: Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use = generic > > > > decode > > > >=20 > > > > * Babu Moger (babu.moger@amd.com) wrote: =20 > > > > > =20 > > > > > > -----Original Message----- > > > > > > From: Igor Mammedov > > > > > > Sent: Wednesday, August 26, 2020 8:31 AM > > > > > > To: Daniel P. Berrang=C3=83=C2=A9 > > > > > > Cc: Moger, Babu ; pbonzini@redhat.com; > > > > > > rth@twiddle.net; ehabkost@redhat.com; qemu-devel@nongnu.org; > > > > > > mst@redhat.com; Michal Privoznik > > > > > > Subject: Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and = use > > > > > > generic decode > > > > > > > > > > > > On Wed, 26 Aug 2020 13:50:59 +0100 > > > > > > Daniel P. Berrang=C3=83=C2=A9 wrote: > > > > > > =20 > > > > > > > On Wed, Aug 26, 2020 at 02:38:49PM +0200, Igor Mammedov wrote= : =20 > > > > > > > > On Fri, 21 Aug 2020 17:12:19 -0500 Babu Moger > > > > > > > > wrote: > > > > > > > > =20 > > > > > > > > > To support some of the complex topology, we introduced EP= YC > > > > > > > > > mode =20 > > > > > > apicid decode. =20 > > > > > > > > > But, EPYC mode decode is running into problems. Also it c= an > > > > > > > > > become quite a maintenance problem in the future. So, it = was > > > > > > > > > decided to remove that code and use the generic decode wh= ich > > > > > > > > > works for majority of the topology. Most of the SPECed > > > > > > > > > configuration would work just fine. With some non-SPECed = user > > > > > > > > > inputs, it will create some sub- =20 > > > > > > optimal configuration. =20 > > > > > > > > > Here is the discussion thread. > > > > > > > > > https://nam11.safelinks.protection.outlook.com/?url=3Dhtt= ps%3A%2 > > > > > > > > > F%2F > > > > > > > > > lore.kernel.org%2Fqemu-devel%2Fc0bcc1a6-1d84-a6e7-e468- = =20 > > > > > > d5b437c1b25 =20 > > > > > > > > > =20 > > > > > > =20 > > > > 4%40amd.com%2F&data=3D02%7C01%7Cbabu.moger%40amd.com%7C8a5c =20 > > > > > > 52f92 =20 > > > > > > > > > =20 > > > > > > =20 > > > > 3f04082a40808d849c43d49%7C3dd8961fe4884e608e11a82d994e183d%7C0%7 = =20 > > > > > > C0 =20 > > > > > > > > > =20 > > > > > > =20 > > > > %7C637340454473508873&sdata=3DVnW28H1v4XwK3GaNGFxu%2BhwiMeA =20 > > > > > > YO%2B =20 > > > > > > > > > 3WAzo3DeY5Ha8%3D&reserved=3D0 > > > > > > > > > > > > > > > > > > This series removes all the EPYC mode specific apicid cha= nges > > > > > > > > > and use the generic apicid decode. =20 > > > > > > > > > > > > > > > > the main difference between EPYC and all other CPUs is that= it > > > > > > > > requires numa configuration (it's not optional) so we need = an > > > > > > > > extra =20 > > > > > No, That is not true. Because of that assumption we made all thes= e > > > > > apicid changes. And here we are now. > > > > > > > > > > AMD supports varies mixed configurations. In case of EPYC-Rome, w= e > > > > > have NPS1, NPS2 and NPS4(Numa Nodes per socket). In case of NPS1, > > > > > basically we have all the cores in a socket under one numa node. = This > > > > > is non-numa configuration. > > > > > Looking at the various configurations and also discussing interna= lly, > > > > > it is not advisable to have (epyc && !numa) check. =20 > > > >=20 > > > > Indeed on real hardware, I don't think we always see NUMA; my singl= e socket, > > > > 16 core/32 thread 7302P Dell box, shows the kernel printing 'No NUM= A > > > > configuration found...Faking a node.' =20 > > looks like firmware bug or maybe it's feature and there is a knob in fw > > to turn it on/off in case used OS doesn't like it for some reason. > >=20 > > =20 > > > > So if real hardware hasn't got a NUMA node, what's the real problem= ? =20 > > >=20 > > > I don't see any problem once we revert all these changes(patch 1-7). > > > We don't need if (epyc && !numa) error check or auto_enable_numa=3Dtr= ue > > > unconditionally. =20 > >=20 > > We need revert to unbreak migration from QEMU < 5.0, > > everything else (fixes for CPUID_Fn8000001E) could go on top. > >=20 > > So what's on top (because old code also wasn't correct when > > CPUID_Fn8000001E is taken in account, tha's why we are at this point), > >=20 > > When starting QEMU without -numa > > Indeed we can skip "if (epyc && !numa) error check or auto_enable_numa= =3Dtrue", > > in case where there is 1 die (NPS1). > > (1) User however may set core/threads number bigger than possible by sp= ec, > > in which case CPUID_Fn8000001E_EBX/CPUID_Fn8000001E_ECX will not be > > valid spec vise and could trigger OPPs in guest kernel. > > Given we allow go out of spec, perhaps we should add a warning at > > realize time saying that used -smp config is not supported since it > > doesn't match AMD EPYC spec and might not work. > >=20 > > (2) Earlier we agreed that we can reuse existing die_id instead of inte= rnal > > (topo_ids.node_id in current code) > > (It's is called DIE_ID and NODE ID in spec interchangeably) > > Same as (1) add a warning when '-smp dies' goes beyond spec limits. > > =20 > > (3) "-smp dies>1" ''if'' we allow to run it without -numa, > > then system wide NUMA node id in CPUID_Fn8000001E_ECX probably does= n't matter. > > could be something like in spec but taking in account die offset, t= o produce > > unique id. > >=20 > > Same, add a warning that there are more than 1 dies but numa is not= enabled, > > suggest to enable numa. > >=20 > > With current code it produces invalid APIC ID for valid '-smp' comb= ination, > > however if we revert it and switch to die_id than it should produce > > valid APIC ID once again (as in 4.2). > > Given it produces invalid APIC id, maybe we should just ditch the c= ase and > > fold it in (4) (i.e. require -numa if "-smp dies>1") > >=20 > > (4) -numa is used (RHBZ1728166) > > we need to ensure that socket*dies =3D=3D ms->numa_state->num_nodes > > and make sure that CPUID_Fn8000001E_ECX consistent with > > cpu mapping provided with "-numa cpu=3D" option. =20 >=20 > Why do we need to socket*dies =3D=3D ms->numa_state->num_nodes ? That doe= sn't > seem to be the case in bare metal EPYC nodes I've used which lets you > configure how many NUMA nodes in firmware. (From dumps Babu has provided earlier, it was dies =3D=3D nodes and CPUID_Fn8000001E_ECX =3D=3D numa node ids in SRAT.) dumping CPUID_Fn8000001E and SRAT table for such configs will help us to figure out if we need socket*dies !=3D nodes and how to compose config were SRAT differs from CPUID_Fn8000001E_ECX. Babu, can you provide CPUID_Fn8000001E and SRAT dumps for above configs combinations? Or to some spec/guide how it should be. >=20 >=20 > Regards, > Daniel