Re: [Qemu-devel] [PATCH v9 05/11] numa: Extend CLI to provide initiator information for numa nodes

[Dan Williams]

On Tue, Aug 13, 2019 at 8:00 AM Igor Mammedov <address@hidden> wrote:
>
> On Fri,  9 Aug 2019 14:57:25 +0800
> Tao <address@hidden> wrote:
>
> > From: Tao Xu <address@hidden>
> >
> > In ACPI 6.3 chapter 5.2.27 Heterogeneous Memory Attribute Table (HMAT),
> > The initiator represents processor which access to memory. And in 5.2.27.3
> > Memory Proximity Domain Attributes Structure, the attached initiator is
> > defined as where the memory controller responsible for a memory proximity
> > domain. With attached initiator information, the topology of heterogeneous
> > memory can be described.
> >
> > Extend CLI of "-numa node" option to indicate the initiator numa node-id.
> > In the linux kernel, the codes in drivers/acpi/hmat/hmat.c parse and report
> > the platform's HMAT tables.
> >
> > Reviewed-by: Jingqi Liu <address@hidden>
> > Suggested-by: Dan Williams <address@hidden>
> > Signed-off-by: Tao Xu <address@hidden>
> > ---
> >
> > No changes in v9
> > ---
> >  hw/core/machine.c     | 24 ++++++++++++++++++++++++
> >  hw/core/numa.c        | 13 +++++++++++++
> >  include/sysemu/numa.h |  3 +++
> >  qapi/machine.json     |  6 +++++-
> >  qemu-options.hx       | 27 +++++++++++++++++++++++----
> >  5 files changed, 68 insertions(+), 5 deletions(-)
> >
> > diff --git a/hw/core/machine.c b/hw/core/machine.c
> > index 3c55470103..113184a9df 100644
> > --- a/hw/core/machine.c
> > +++ b/hw/core/machine.c
> > @@ -640,6 +640,7 @@ void machine_set_cpu_numa_node(MachineState *machine,
> >                                 const CpuInstanceProperties *props, Error 
> > **errp)
> >  {
> >      MachineClass *mc = MACHINE_GET_CLASS(machine);
> > +    NodeInfo *numa_info = machine->numa_state->nodes;
> >      bool match = false;
> >      int i;
> >
> > @@ -709,6 +710,16 @@ void machine_set_cpu_numa_node(MachineState *machine,
> >          match = true;
> >          slot->props.node_id = props->node_id;
> >          slot->props.has_node_id = props->has_node_id;
> > +
> > +        if (numa_info[props->node_id].initiator_valid &&
> > +            (props->node_id != numa_info[props->node_id].initiator)) {
> > +            error_setg(errp, "The initiator of CPU NUMA node %" PRId64
> > +                       " should be itself.", props->node_id);
> > +            return;
> > +        }
> > +        numa_info[props->node_id].initiator_valid = true;
> > +        numa_info[props->node_id].has_cpu = true;
> > +        numa_info[props->node_id].initiator = props->node_id;
> >      }
> >
> >      if (!match) {
> > @@ -1050,6 +1061,7 @@ static void machine_numa_finish_cpu_init(MachineState 
> > *machine)
> >      GString *s = g_string_new(NULL);
> >      MachineClass *mc = MACHINE_GET_CLASS(machine);
> >      const CPUArchIdList *possible_cpus = 
> > mc->possible_cpu_arch_ids(machine);
> > +    NodeInfo *numa_info = machine->numa_state->nodes;
> >
> >      assert(machine->numa_state->num_nodes);
> >      for (i = 0; i < possible_cpus->len; i++) {
> > @@ -1083,6 +1095,18 @@ static void 
> > machine_numa_finish_cpu_init(MachineState *machine)
> >              machine_set_cpu_numa_node(machine, &props, &error_fatal);
> >          }
> >      }
> > +
> > +    for (i = 0; i < machine->numa_state->num_nodes; i++) {
> > +        if (numa_info[i].initiator_valid &&
> > +            !numa_info[numa_info[i].initiator].has_cpu) {
>                           ^^^^^^^^^^^^^^^^^^^^^^ possible out of bounds read, 
> see bellow
>
> > +            error_report("The initiator-id %"PRIu16 " of NUMA node %d"
> > +                         " does not exist.", numa_info[i].initiator, i);
> > +            error_printf("\n");
> > +
> > +            exit(1);
> > +        }
> it takes care only about nodes that have cpus or memory-only ones that have
> initiator explicitly provided on CLI. And leaves possibility to have
> memory-only nodes without initiator mixed with nodes that have initiator.
> Is it valid to have mixed configuration?
> Should we forbid it?

The spec talks about the "Proximity Domain for the Attached Initiator"
field only being valid if the memory controller for the memory can be
identified by an initiator id in the SRAT. So I expect the only way to
define a memory proximity domain without this local initiator is to
allow specifying a node-id that does not have an entry in the SRAT.

That would be a useful feature for testing OS HMAT parsing behavior,
and may match platforms that exist in practice.

>
> > +    }
> > +
> >      if (s->len && !qtest_enabled()) {
> >          warn_report("CPU(s) not present in any NUMA nodes: %s",
> >                      s->str);
> > diff --git a/hw/core/numa.c b/hw/core/numa.c
> > index 8fcbba05d6..cfb6339810 100644
> > --- a/hw/core/numa.c
> > +++ b/hw/core/numa.c
> > @@ -128,6 +128,19 @@ static void parse_numa_node(MachineState *ms, 
> > NumaNodeOptions *node,
> >          numa_info[nodenr].node_mem = object_property_get_uint(o, "size", 
> > NULL);
> >          numa_info[nodenr].node_memdev = MEMORY_BACKEND(o);
> >      }
> > +
> > +    if (node->has_initiator) {
> > +        if (numa_info[nodenr].initiator_valid &&
> > +            (node->initiator != numa_info[nodenr].initiator)) {
> > +            error_setg(errp, "The initiator of NUMA node %" PRIu16 " has 
> > been "
> > +                       "set to node %" PRIu16, nodenr,
> > +                       numa_info[nodenr].initiator);
> > +            return;
> > +        }
> > +
> > +        numa_info[nodenr].initiator_valid = true;
> > +        numa_info[nodenr].initiator = node->initiator;
>                                              ^^^
> not validated  user input? (which could lead to read beyond numa_info[] 
> boundaries
> in previous hunk).
>
> > +    }
> >      numa_info[nodenr].present = true;
> >      max_numa_nodeid = MAX(max_numa_nodeid, nodenr + 1);
> >      ms->numa_state->num_nodes++;
> > diff --git a/include/sysemu/numa.h b/include/sysemu/numa.h
> > index 76da3016db..46ad06e000 100644
> > --- a/include/sysemu/numa.h
> > +++ b/include/sysemu/numa.h
> > @@ -10,6 +10,9 @@ struct NodeInfo {
> >      uint64_t node_mem;
> >      struct HostMemoryBackend *node_memdev;
> >      bool present;
> > +    bool has_cpu;
> > +    bool initiator_valid;
> > +    uint16_t initiator;
> >      uint8_t distance[MAX_NODES];
> >  };
> >
> > diff --git a/qapi/machine.json b/qapi/machine.json
> > index 6db8a7e2ec..05e367d26a 100644
> > --- a/qapi/machine.json
> > +++ b/qapi/machine.json
> > @@ -414,6 +414,9 @@
> >  # @memdev: memory backend object.  If specified for one node,
> >  #          it must be specified for all nodes.
> >  #
> > +# @initiator: the initiator numa nodeid that is closest (as in directly
> > +#             attached) to this numa node (since 4.2)
> well, it's pretty unclear what doc comment means (unless reader knows well
> specific part of ACPI spec)
>
> suggest to rephrase to something more understandable for unaware
> readers (+ possible reference to spec for those who is interested
> in spec definition since this doc is meant for developers).
>
> > +#
> >  # Since: 2.1
> >  ##
> >  { 'struct': 'NumaNodeOptions',
> > @@ -421,7 +424,8 @@
> >     '*nodeid': 'uint16',
> >     '*cpus':   ['uint16'],
> >     '*mem':    'size',
> > -   '*memdev': 'str' }}
> > +   '*memdev': 'str',
> > +   '*initiator': 'uint16' }}
> >
> >  ##
> >  # @NumaDistOptions:
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 9621e934c0..c480781992 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -161,14 +161,14 @@ If any on the three values is given, the total number 
> > of CPUs @var{n} can be omi
> >  ETEXI
> >
> >  DEF("numa", HAS_ARG, QEMU_OPTION_numa,
> > -    "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n"
> > -    "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n"
> > +    "-numa 
> > node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
> > +    "-numa 
> > node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
> >      "-numa dist,src=source,dst=destination,val=distance\n"
> >      "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n",
> >      QEMU_ARCH_ALL)
> >  STEXI
> > -@item -numa 
> > node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
> > -@itemx -numa 
> > node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
> > +@item -numa 
> > node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
> > +@itemx -numa 
> > node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
> >  @itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
> >  @itemx -numa 
> > cpu,node-id=@var{node}[,socket-id=@var{x}][,core-id=@var{y}][,thread-id=@var{z}]
> >  @findex -numa
> > @@ -215,6 +215,25 @@ split equally between them.
> >  @samp{mem} and @samp{memdev} are mutually exclusive. Furthermore,
> >  if one node uses @samp{memdev}, all of them have to use it.
> >
> > +@samp{initiator} indicate the initiator NUMA @var{initiator} that is
>                                   ^^^^^^^       ^^^^^^^^^^^^^^
> above will result in "initiator NUMA initiator", was it your intention?
>
> > +closest (as in directly attached) to this NUMA @var{node}.
> Again suggest replace spec language with something more user friendly
> (this time without spec reference as it's geared for end user)
>
> > +For example, the following option assigns 2 NUMA nodes, node 0 has CPU.
> Following example creates a machine with 2 NUMA ...
>
> > +node 1 has only memory, and its' initiator is node 0. Note that because
> > +node 0 has CPU, by default the initiator of node 0 is itself and must be
> > +itself.
> > +@example
> > +-M pc \
> > +-m 2G,slots=2,maxmem=4G \
> > +-object memory-backend-ram,size=1G,id=m0 \
> > +-object memory-backend-ram,size=1G,id=m1 \
> > +-numa node,nodeid=0,memdev=m0 \
> > +-numa node,nodeid=1,memdev=m1,initiator=0 \
> > +-smp 2,sockets=2,maxcpus=2  \
> > +-numa cpu,node-id=0,socket-id=0 \
> > +-numa cpu,node-id=0,socket-id=1 \
> > +@end example
> > +
> >  @var{source} and @var{destination} are NUMA node IDs.
> >  @var{distance} is the NUMA distance from @var{source} to @var{destination}.
> >  The distance from a node to itself is always 10. If any pair of nodes is
>