arch_topology: Make cluster topology span at least SMT CPUs

Currently cpu_clustergroup_mask() will return CPU mask if cluster span more
or the same CPUs as cpu_coregroup_mask(). This will result topology borken
on non-Cluster SMT machines when building with CONFIG_SCHED_CLUSTER=y.

Test with:
qemu-system-aarch64 -enable-kvm -machine virt \
 -net none \
 -cpu host \
 -bios ./QEMU_EFI.fd \
 -m 2G \
 -smp 48,sockets=2,cores=12,threads=2 \
 -kernel $Image \
 -initrd $Rootfs \
 -nographic
 -append "rdinit=init console=ttyAMA0 sched_verbose loglevel=8"

We'll get below error:
[    3.084568] BUG: arch topology borken
[    3.084570]      the SMT domain not a subset of the CLS domain

Since cluster is a level higher than SMT, fix this by making cluster
spans at least SMT CPUs.

Fixes: bfcc4397435d ("arch_topology: Limit span of cpu_clustergroup_mask()")
Cc: Sudeep Holla <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: Ionela Voinescu <[email protected]>
Cc: Greg KH <[email protected]>
Reviewed-by: Sudeep Holla <[email protected]>
Signed-off-by: Yicong Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index eaa1b8d2d39d37b06682420b0560b92ecdf79ba5..46cbe4471e785f577f3d1cd9196316e681957688 100644 (file)
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -724,7 +724,7 @@ const struct cpumask *cpu_clustergroup_mask(int cpu)
         */
        if (cpumask_subset(cpu_coregroup_mask(cpu),
                           &cpu_topology[cpu].cluster_sibling))
-               return get_cpu_mask(cpu);
+               return topology_sibling_cpumask(cpu);
 
        return &cpu_topology[cpu].cluster_sibling;
 }