From ed44a5625f304ff14d01acfa086e77b5262a842f Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Sun, 21 Sep 2025 15:48:35 -0700 Subject: x86/cpu/topology: Make primary thread mask available with SMP=n cpu_primary_thread_mask is only defined when CONFIG_SMP=y. However, even in UP kernels there is always exactly one CPU, which can reasonably be treated as the primary thread. Historically, topology_is_primary_thread() always returned true with CONFIG_SMP=n. A recent commit: 4b455f59945aa ("cpu/SMT: Provide a default topology_is_primary_thread()") replaced it with a generic implementation with the note: "When disabling SMT, the primary thread of the SMT will remain enabled/active. Architectures that have a special primary thread (e.g. x86) need to override this function. ..." For consistency and clarity, make the primary thread mask available regardless of SMP, similar to cpu_possible_mask and cpu_present_mask. Move __cpu_primary_thread_mask into common code to prevent build issues. Let cpu_mark_primary_thread() configure the mask even for UP kernels, alongside other masks. Then, topology_is_primary_thread() can consistently reference it. Signed-off-by: Chang S. Bae Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tony Luck Link: https://lore.kernel.org/r/20250320234104.8288-1-chang.seok.bae@intel.com --- arch/x86/kernel/smpboot.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/x86/kernel/smpboot.c') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index eb289abece23..6b43417bf270 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -103,9 +103,6 @@ EXPORT_PER_CPU_SYMBOL(cpu_core_map); DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_die_map); EXPORT_PER_CPU_SYMBOL(cpu_die_map); -/* CPUs which are the primary SMT threads */ -struct cpumask __cpu_primary_thread_mask __read_mostly; - /* Representing CPUs for which sibling maps can be computed */ static cpumask_var_t cpu_sibling_setup_mask; -- cgit