Re: [PATCH v2 2/4] numa: Validate socket and NUMA node boundary if required

[Gavin Shan]

On 2/23/23 8:05 PM, Philippe Mathieu-Daudé wrote:
> On 23/2/23 09:13, Gavin Shan wrote:
> > For some architectures like ARM64, multiple CPUs in one socket can't be
> > associated with different NUMA nodes. Otherwise, the guest kernel is confused
> > about the CPU topology. For example, the following warning message is observed
> > from linux guest with the below command lines.
> >
> >    -smp 6,maxcpus=6,sockets=2,clusters=1,cores=3,threads=1 \
> >    -numa node,nodeid=0,cpus=0-1,memdev=ram0                \
> >    -numa node,nodeid=1,cpus=2-3,memdev=ram1                \
> >    -numa node,nodeid=2,cpus=4-5,memdev=ram2                \
> >
> >    ------------[ cut here ]------------
> >    WARNING: CPU: 0 PID: 1 at kernel/sched/topology.c:2271 
> > build_sched_domains+0x284/0x910
> >    Modules linked in:
> >    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0-268.el9.aarch64 #1
> >    pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> >    pc : build_sched_domains+0x284/0x910
> >    lr : build_sched_domains+0x184/0x910
> >    sp : ffff80000804bd50
> >    x29: ffff80000804bd50 x28: 0000000000000002 x27: 0000000000000000
> >    x26: ffff800009cf9a80 x25: 0000000000000000 x24: ffff800009cbf840
> >    x23: ffff000080325000 x22: ffff0000005df800 x21: ffff80000a4ce508
> >    x20: 0000000000000000 x19: ffff000080324440 x18: 0000000000000014
> >    x17: 00000000388925c0 x16: 000000005386a066 x15: 000000009c10cc2e
> >    x14: 00000000000001c0 x13: 0000000000000001 x12: ffff00007fffb1a0
> >    x11: ffff00007fffb180 x10: ffff80000a4ce508 x9 : 0000000000000041
> >    x8 : ffff80000a4ce500 x7 : ffff80000a4cf920 x6 : 0000000000000001
> >    x5 : 0000000000000001 x4 : 0000000000000007 x3 : 0000000000000002
> >    x2 : 0000000000001000 x1 : ffff80000a4cf928 x0 : 0000000000000001
> >    Call trace:
> >     build_sched_domains+0x284/0x910
> >     sched_init_domains+0xac/0xe0
> >     sched_init_smp+0x48/0xc8
> >     kernel_init_freeable+0x140/0x1ac
> >     kernel_init+0x28/0x140
> >     ret_from_fork+0x10/0x20
> >
> > Improve the sitation to reject the configuration where multiple CPUs
>
> Typo "situation".

Yes, I will fix it up in next revision.

> > in one socket have been associated with different NUMA nodes. The
> > newly introduced helper set_numa_socket_boundary() is expected to
> > called by specific machines (boards) where the boundary is required.
> >
> > Signed-off-by: Gavin Shan <gshan@redhat.com>
> > ---
> >   hw/core/machine.c     | 34 ++++++++++++++++++++++++++++++++++
> >   hw/core/numa.c        |  7 +++++++
> >   include/sysemu/numa.h |  4 ++++
> >   3 files changed, 45 insertions(+)
>
>
> > diff --git a/include/sysemu/numa.h b/include/sysemu/numa.h
> > index 4173ef2afa..160008fff4 100644
> > --- a/include/sysemu/numa.h
> > +++ b/include/sysemu/numa.h
> > @@ -86,6 +86,9 @@ struct NumaState {
> >       /* Detect if HMAT support is enabled. */
> >       bool hmat_enabled;
> > +    /* CPUs in one socket can't break socket boundary */
> > +    bool have_socket_boundary;
>
> This field belong to MachineClass, please add it as
> numa_have_socket_boundary just after to numa_mem_supported.
>
> Next patches become:
>
> ---
> diff --git a/hw/arm/sbsa-ref.c b/hw/arm/sbsa-ref.c
> index f778cb6d09..a48f1b2329 100644
> --- a/hw/arm/sbsa-ref.c
> +++ b/hw/arm/sbsa-ref.c
> @@ -864,6 +864,7 @@ static void sbsa_ref_class_init(ObjectClass *oc, void *data)
>       mc->possible_cpu_arch_ids = sbsa_ref_possible_cpu_arch_ids;
>       mc->cpu_index_to_instance_props = sbsa_ref_cpu_index_to_props;
>       mc->get_default_cpu_node_id = sbsa_ref_get_default_cpu_node_id;
> +    mc->numa_have_socket_boundary = true;
>   }
> ---
>
> Otherwise LGTM :)

Thanks, Philippe. It makes sense to have the field in MachineClass and the
changes will be included in next revision.

Thanks,
Gavin