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Tue, 2 Jun 2020 23:01:06 +0000 (UTC) Date: Tue, 2 Jun 2020 19:01:05 -0400 From: Eduardo Habkost To: Babu Moger Subject: Re: [PATCH v7 07/13] hw/386: Add EPYC mode topology decoding functions Message-ID: <20200602230105.GI577771@habkost.net> References: <158396702138.58170.7920458595372792959.stgit@naples-babu.amd.com> <158396721426.58170.2930696192478912976.stgit@naples-babu.amd.com> <20200602171838.GG577771@habkost.net> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/02 15:54:57 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: "mst@redhat.com" , "qemu-devel@nongnu.org" , "imammedo@redhat.com" , "pbonzini@redhat.com" , "rth@twiddle.net" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jun 02, 2020 at 04:59:19PM -0500, Babu Moger wrote: > > > > -----Original Message----- > > From: Eduardo Habkost > > Sent: Tuesday, June 2, 2020 12:19 PM > > To: Moger, Babu > > Cc: marcel.apfelbaum@gmail.com; pbonzini@redhat.com; rth@twiddle.net; > > mst@redhat.com; imammedo@redhat.com; qemu-devel@nongnu.org > > Subject: Re: [PATCH v7 07/13] hw/386: Add EPYC mode topology decoding > > functions > > > > Hi, > > > > It looks like this series breaks -device and CPU hotplug: > > > > On Wed, Mar 11, 2020 at 05:53:34PM -0500, Babu Moger wrote: > > > These functions add support for building EPYC mode topology given the smp > > > details like numa nodes, cores, threads and sockets. > > > > > > The new apic id decoding is mostly similar to current apic id decoding > > > except that it adds a new field node_id when numa configured. Removes all > > > the hardcoded values. Subsequent patches will use these functions to build > > > the topology. > > > > > > Following functions are added. > > > apicid_llc_width_epyc > > > apicid_llc_offset_epyc > > > apicid_pkg_offset_epyc > > > apicid_from_topo_ids_epyc > > > x86_topo_ids_from_idx_epyc > > > x86_topo_ids_from_apicid_epyc > > > x86_apicid_from_cpu_idx_epyc > > > > > > The topology details are available in Processor Programming Reference (PPR) > > > for AMD Family 17h Model 01h, Revision B1 Processors. The revision guides > > are > > > available from the bugzilla Link below. > > > Link: > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla. > > kernel.org%2Fshow_bug.cgi%3Fid%3D206537&data=02%7C01%7Cbabu.m > > oger%40amd.com%7C3487f40d37df4d59097d08d807190248%7C3dd8961fe488 > > 4e608e11a82d994e183d%7C0%7C0%7C637267151289763739&sdata=wE0 > > ukXIVh0l5eNQWsv6VDE9UZEVJmisofaW192gcZAI%3D&reserved=0 > > > > > > Signed-off-by: Babu Moger > > > Acked-by: Igor Mammedov > > > Acked-by: Michael S. Tsirkin > > > --- > > [...] > > > typedef struct X86CPUTopoIDs { > > > unsigned pkg_id; > > > + unsigned node_id; > > > > You have added a new field here. > > > > > unsigned die_id; > > > unsigned core_id; > > > unsigned smt_id; > > [...] > > > +static inline apic_id_t > > > +x86_apicid_from_topo_ids_epyc(X86CPUTopoInfo *topo_info, > > > + const X86CPUTopoIDs *topo_ids) > > > +{ > > > + return (topo_ids->pkg_id << apicid_pkg_offset_epyc(topo_info)) | > > > + (topo_ids->node_id << apicid_node_offset_epyc(topo_info)) | > > > > You are using the new field here. > > > > > + (topo_ids->die_id << apicid_die_offset(topo_info)) | > > > + (topo_ids->core_id << apicid_core_offset(topo_info)) | > > > + topo_ids->smt_id; > > > +} > > > > But you are not initializing node_id in one caller of apicid_from_topo_ids(): > > > > static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev, > > DeviceState *dev, Error **errp) > > { > > [...] > > X86CPUTopoIDs topo_ids; > > [...] > > if (cpu->apic_id == UNASSIGNED_APIC_ID) { > > [...] > > topo_ids.pkg_id = cpu->socket_id; > > topo_ids.die_id = cpu->die_id; > > topo_ids.core_id = cpu->core_id; > > topo_ids.smt_id = cpu->thread_id; > > cpu->apic_id = x86ms->apicid_from_topo_ids(&topo_info, &topo_ids); > > } > > [...] > > } > > > > Result: -device is broken when using -cpu EPYC: > > > > $ qemu-system-x86_64 -machine q35,accel=kvm -smp > > 1,maxcpus=2,cores=1,threads=1,sockets=2 -cpu EPYC -device EPYC-x86_64- > > cpu,core-id=0,socket-id=1,thread-id=0 [1] > > qemu-system-x86_64: -device EPYC-x86_64-cpu,core-id=0,socket-id=1,thread- > > id=0: Invalid CPU [socket: 21855, die: 0, core: 0, thread: 0] with APIC ID 21855, > > valid index range 0:1 > > > > This happens because APIC ID is calculated using uninitialized > > memory. > This patch should initialize the node_id. But I am not sure how to > reproduce the bug. Can you please send me the full command line to > reproduce the problem. Also test different options. The full command line is above[1]. > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index 2128f3d6fe..047b4b9391 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1539,6 +1539,9 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev, > if (cpu->apic_id == UNASSIGNED_APIC_ID) { > int max_socket = (ms->smp.max_cpus - 1) / > smp_threads / smp_cores / x86ms->smp_dies; So, here's the input you are using to calculate topo_ids.node_id: > + unsigned nr_nodes = MAX(topo_info.nodes_per_pkg, 1); When is topo_info.nodes_per_pkg allowed to be 0? > + unsigned cores_per_node = DIV_ROUND_UP((x86ms->smp_dies * smp_cores * > + smp_threads), nr_nodes); x86ms->smp_dies should be available at topo_info.dies_per_pkg, smp_cores should available at topo_info.cores_per_die, smp_threads should be available at topo_info.threads_per_core, nr_nodes should be available at topo_info.nodes_per_pkg. > > /* > * die-id was optional in QEMU 4.0 and older, so keep it optional > @@ -1585,6 +1588,7 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev, > topo_ids.die_id = cpu->die_id; > topo_ids.core_id = cpu->core_id; > topo_ids.smt_id = cpu->thread_id; > + topo_ids.node_id = (cpu->core_id / cores_per_node) % nr_nodes; apicid_from_topo_ids() have access to topo_info and topo_ids, If all the information you need to calculate node_id is already available inside topo_info + topo_ids, we could be calculating it inside apicid_from_topo_ids(). Why don't we do it? Also, is topo_ids.core_id really allowed to be larger than cores_per_node when calling apicid_from_topo_ids()? > cpu->apic_id = x86ms->apicid_from_topo_ids(&topo_info, &topo_ids); > } > -- Eduardo