x86/apic: Provide cpu_primary_thread mask

Make the primary thread tracking CPU mask based in preparation for simpler
handling of parallel bootup.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205257.186599880@linutronix.de

arch/x86/include/asm/apic.h

@@ -506,10 +506,8 @@ extern int default_check_phys_apicid_present(int phys_apicid);
 #endif /* CONFIG_X86_LOCAL_APIC */
 
 #ifdef CONFIG_SMP
-bool apic_id_is_primary_thread(unsigned int id);
 void apic_smt_update(void);
 #else
-static inline bool apic_id_is_primary_thread(unsigned int id) { return false; }
 static inline void apic_smt_update(void) { }
 #endif
 

arch/x86/include/asm/topology.h

@@ -31,9 +31,9 @@
  * CONFIG_NUMA.
  */
 #include <linux/numa.h>
+#include <linux/cpumask.h>
 
 #ifdef CONFIG_NUMA
-#include <linux/cpumask.h>
 
 #include <asm/mpspec.h>
 #include <asm/percpu.h>
@@ -139,9 +139,20 @@ static inline int topology_max_smt_threads(void)
 int topology_update_package_map(unsigned int apicid, unsigned int cpu);
 int topology_update_die_map(unsigned int dieid, unsigned int cpu);
 int topology_phys_to_logical_pkg(unsigned int pkg);
-bool topology_is_primary_thread(unsigned int cpu);
 bool topology_smt_supported(void);
-#else
+
+extern struct cpumask __cpu_primary_thread_mask;
+#define cpu_primary_thread_mask ((const struct cpumask *)&__cpu_primary_thread_mask)
+
+/**
+ * topology_is_primary_thread - Check whether CPU is the primary SMT thread
+ * @cpu:	CPU to check
+ */
+static inline bool topology_is_primary_thread(unsigned int cpu)
+{
+	return cpumask_test_cpu(cpu, cpu_primary_thread_mask);
+}
+#else /* CONFIG_SMP */
 #define topology_max_packages()			(1)
 static inline int
 topology_update_package_map(unsigned int apicid, unsigned int cpu) { return 0; }
@@ -152,7 +163,7 @@ static inline int topology_max_die_per_package(void) { return 1; }
 static inline int topology_max_smt_threads(void) { return 1; }
 static inline bool topology_is_primary_thread(unsigned int cpu) { return true; }
 static inline bool topology_smt_supported(void) { return false; }
-#endif
+#endif /* !CONFIG_SMP */
 
 static inline void arch_fix_phys_package_id(int num, u32 slot)
 {

arch/x86/kernel/apic/apic.c

@@ -2386,20 +2386,16 @@ bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 }
 
 #ifdef CONFIG_SMP
-/**
- * apic_id_is_primary_thread - Check whether APIC ID belongs to a primary thread
- * @apicid: APIC ID to check
- */
-bool apic_id_is_primary_thread(unsigned int apicid)
+static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)
 {
-	u32 mask;
-
-	if (smp_num_siblings == 1)
-		return true;
 	/* Isolate the SMT bit(s) in the APICID and check for 0 */
-	mask = (1U << (fls(smp_num_siblings) - 1)) - 1;
-	return !(apicid & mask);
+	u32 mask = (1U << (fls(smp_num_siblings) - 1)) - 1;
+
+	if (smp_num_siblings == 1 || !(apicid & mask))
+		cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
 }
+#else
+static inline void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid) { }
 #endif
 
 /*
@@ -2544,6 +2540,8 @@ int generic_processor_info(int apicid, int version)
 	set_cpu_present(cpu, true);
 	num_processors++;
 
+	cpu_mark_primary_thread(cpu, apicid);
+
 	return cpu;
 }
 

arch/x86/kernel/smpboot.c

@@ -102,6 +102,9 @@ EXPORT_PER_CPU_SYMBOL(cpu_die_map);
 DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);
 EXPORT_PER_CPU_SYMBOL(cpu_info);
 
+/* 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;
 
@@ -276,15 +279,6 @@ static void notrace start_secondary(void *unused)
 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 }
 
-/**
- * topology_is_primary_thread - Check whether CPU is the primary SMT thread
- * @cpu:	CPU to check
- */
-bool topology_is_primary_thread(unsigned int cpu)
-{
-	return apic_id_is_primary_thread(per_cpu(x86_cpu_to_apicid, cpu));
-}
-
 /**
  * topology_smt_supported - Check whether SMT is supported by the CPUs
  */