On Wed, Jun 03, 2020 at 10:22:10AM -0500, Babu Moger wrote: > > > > -----Original Message----- > > From: Eduardo Habkost <ehabk...@redhat.com> > > Sent: Tuesday, June 2, 2020 6:01 PM > > To: Moger, Babu <babu.mo...@amd.com> > > Cc: marcel.apfelb...@gmail.com; pbonz...@redhat.com; r...@twiddle.net; > > m...@redhat.com; imamm...@redhat.com; qemu-devel@nongnu.org > > Subject: Re: [PATCH v7 07/13] hw/386: Add EPYC mode topology decoding > > functions > > > > On Tue, Jun 02, 2020 at 04:59:19PM -0500, Babu Moger wrote: > > > > > > > > > > -----Original Message----- > > > > From: Eduardo Habkost <ehabk...@redhat.com> > > > > Sent: Tuesday, June 2, 2020 12:19 PM > > > > To: Moger, Babu <babu.mo...@amd.com> > > > > Cc: marcel.apfelb...@gmail.com; pbonz...@redhat.com; r...@twiddle.net; > > > > m...@redhat.com; imamm...@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 <babu.mo...@amd.com> > > > > > Acked-by: Igor Mammedov <imamm...@redhat.com> > > > > > Acked-by: Michael S. Tsirkin <m...@redhat.com> > > > > > --- > > > > [...] > > > > > 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]. > > I just picked up the latest tree from > git clone https://git.qemu.org/git/qemu.git qemu > Not seeing the problem. > > ./x86_64-softmmu/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 > VNC server running on ::1:5900 > > It appears to run ok. > > > > > > > > > > > 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? > > It will be zero if numa is not configured. Node_id will be zero for all > the cores. > > > > > > + 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()? > > Yes. It is. If we have two numa nodes and 8 cores. Then cores_per_node is > 4. Nr_nodes =2. Yes. Core_id can be larger than cores_per_node.
I assumed core_id identified the core inside a die, and the range would be [0, cores_per_die). This seems to be what apicid_from_topo_ids_epyc() expects. We need clearer documentation on the semantics of each *_id field, to avoid confusion. > > > > > > cpu->apic_id = > > > x86ms->apicid_from_topo_ids(&topo_info, > > > &topo_ids); } > > > > > > > -- Eduardo > -- Eduardo