[patch 31/37] x86/apic: Provide cpu_primary_thread mask

Thomas Gleixner
2023-04-14T23:47:33Z

Make the primary thread tracking CPU mask based in preparation for simpler
handling of parallel bootup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/apic.h | 2 --
arch/x86/include/asm/topology.h | 19 +++++++++++++++----
arch/x86/kernel/apic/apic.c | 20 +++++++++-----------
arch/x86/kernel/smpboot.c | 12 +++---------
4 files changed, 27 insertions(+), 26 deletions(-)

--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -506,10 +506,8 @@ extern int default_check_phys_apicid_pre
#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

--- a/arch/x86/include/asm/topology.h
+++ b/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_threa
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_p
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)
{
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2387,20 +2387,16 @@ bool arch_match_cpu_phys_id(int cpu, u64
}

#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

/*
@@ -2545,6 +2541,8 @@ int generic_processor_info(int apicid, i
set_cpu_present(cpu, true);
num_processors++;

+ cpu_mark_primary_thread(cpu, apicid);
+
return cpu;
}

--- a/arch/x86/kernel/smpboot.c
+++ b/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;

@@ -294,15 +297,6 @@ static void notrace start_secondary(void
}

/**
- * 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
*/
bool topology_smt_supported(void)