Commit 316ad248307fb ("sched/x86: Rewrite set_cpu_sibling_map()") broke
the construction of sibling maps, which also broke the booted_cores
accounting.
Before the rewrite, if smt was present, then each map was updated for
each smt sibling. After the rewrite only cpu_sibling_mask gets updated,
as the llc and core maps depend on 'has_mc = x86_max_cores > 1' instead.
This leads to problems with topologies like the following
(qemu -smp sockets=2,cores=1,threads=2)
processor : 0
physical id : 0
siblings : 1 <= should be 2
core id : 0
cpu cores : 1
processor : 1
physical id : 0
siblings : 1 <= should be 2
core id : 0
cpu cores : 0 <= should be 1
processor : 2
physical id : 1
siblings : 1 <= should be 2
core id : 0
cpu cores : 1
processor : 3
physical id : 1
siblings : 1 <= should be 2
core id : 0
cpu cores : 0 <= should be 1
This patch restores the former construction by defining has_mc as
(has_smt || x86_max_cores > 1). This should be fine as there were no
(has_smt && !has_mc) conditions in the context.
Signed-off-by: Andrew Jones <drjo...@redhat.com>
---
arch/x86/kernel/smpboot.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9c73b51817e47..886a3234eaff3 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -372,15 +372,15 @@ static bool __cpuinit match_mc(struct cpuinfo_x86 *c,
struct cpuinfo_x86 *o)
void __cpuinit set_cpu_sibling_map(int cpu)
{
- bool has_mc = boot_cpu_data.x86_max_cores > 1;
bool has_smt = smp_num_siblings > 1;
+ bool has_mc = has_smt || boot_cpu_data.x86_max_cores > 1;
struct cpuinfo_x86 *c = &cpu_data(cpu);
struct cpuinfo_x86 *o;
int i;
cpumask_set_cpu(cpu, cpu_sibling_setup_mask);
- if (!has_smt && !has_mc) {
+ if (!has_mc) {
cpumask_set_cpu(cpu, cpu_sibling_mask(cpu));
cpumask_set_cpu(cpu, cpu_llc_shared_mask(cpu));
cpumask_set_cpu(cpu, cpu_core_mask(cpu));
--
1.8.1.4
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