[patch 31/53] x86/cpu/topology: Confine topology information

Thomas Gleixner
2023-08-07T13:54:41Z

Now that all external fiddling with num_processors and disabled_cpus is
gone, move the last user prefill_possible_map() into the topology code too
and remove the global visibility of these variables.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/smp.h | 3 -
arch/x86/kernel/apic/apic.c | 1
arch/x86/kernel/cpu/topology.c | 76 +++++++++++++++++++++++++++++++++++-
arch/x86/kernel/smpboot.c | 72 ----------------------------------
4 files changed, 74 insertions(+), 78 deletions(-)

--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -9,7 +9,6 @@
#include <asm/thread_info.h>

extern int smp_num_siblings;
-extern unsigned int num_processors;

DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);
DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_map);
@@ -178,8 +177,6 @@ static inline struct cpumask *cpu_llc_sh
}
#endif /* CONFIG_SMP */

-extern unsigned disabled_cpus;
-
#ifdef CONFIG_DEBUG_NMI_SELFTEST
extern void nmi_selftest(void);
#else
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2054,7 +2054,6 @@ void __init init_apic_mappings(void)
pr_info("APIC: disable apic facility\n");
apic_disable();
}
- num_processors = 1;
}
}

--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -29,8 +29,8 @@ u32 cpuid_to_apicid[] __read_mostly = {
*/
static u32 disabled_cpu_apicid __ro_after_init = BAD_APICID;

-unsigned int num_processors;
-unsigned disabled_cpus;
+static unsigned int num_processors;
+static unsigned int disabled_cpus;

/*
* The number of allocated logical CPU IDs. Since logical CPU IDs are allocated
@@ -169,6 +169,71 @@ static int generic_processor_info(int ap
return cpu;
}

+static int __initdata setup_possible_cpus = -1;
+
+/*
+ * cpu_possible_mask should be static, it cannot change as cpu's
+ * are onlined, or offlined. The reason is per-cpu data-structures
+ * are allocated by some modules at init time, and don't expect to
+ * do this dynamically on cpu arrival/departure.
+ * cpu_present_mask on the other hand can change dynamically.
+ * In case when cpu_hotplug is not compiled, then we resort to current
+ * behaviour, which is cpu_possible == cpu_present.
+ * - Ashok Raj
+ *
+ * Three ways to find out the number of additional hotplug CPUs:
+ * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
+ * - The user can overwrite it with possible_cpus=NUM
+ * - Otherwise don't reserve additional CPUs.
+ * We do this because additional CPUs waste a lot of memory.
+ * -AK
+ */
+__init void prefill_possible_map(void)
+{
+ int i, possible;
+
+ i = setup_max_cpus ?: 1;
+ if (setup_possible_cpus == -1) {
+ possible = num_processors;
+#ifdef CONFIG_HOTPLUG_CPU
+ if (setup_max_cpus)
+ possible += disabled_cpus;
+#else
+ if (possible > i)
+ possible = i;
+#endif
+ } else
+ possible = setup_possible_cpus;
+
+ total_cpus = max_t(int, possible, num_processors + disabled_cpus);
+
+ /* nr_cpu_ids could be reduced via nr_cpus= */
+ if (possible > nr_cpu_ids) {
+ pr_warn("%d Processors exceeds NR_CPUS limit of %u\n",
+ possible, nr_cpu_ids);
+ possible = nr_cpu_ids;
+ }
+
+#ifdef CONFIG_HOTPLUG_CPU
+ if (!setup_max_cpus)
+#endif
+ if (possible > i) {
+ pr_warn("%d Processors exceeds max_cpus limit of %u\n",
+ possible, setup_max_cpus);
+ possible = i;
+ }
+
+ set_nr_cpu_ids(possible);
+
+ pr_info("Allowing %d CPUs, %d hotplug CPUs\n",
+ possible, max_t(int, possible - num_processors, 0));
+
+ reset_cpu_possible_mask();
+
+ for (i = 0; i < possible; i++)
+ set_cpu_possible(i, true);
+}
+
/**
* topology_register_apic - Register an APIC in early topology maps
* @apic_id: The APIC ID to set up
@@ -246,6 +311,13 @@ void topology_hotunplug_apic(unsigned in
}
#endif

+static int __init _setup_possible_cpus(char *str)
+{
+ get_option(&str, &setup_possible_cpus);
+ return 0;
+}
+early_param("possible_cpus", _setup_possible_cpus);
+
static int __init apic_set_disabled_cpu_apicid(char *arg)
{
if (!arg || !get_option(&arg, &disabled_cpu_apicid))
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1327,78 +1327,6 @@ void __init native_smp_cpus_done(unsigne
cache_aps_init();
}

-static int __initdata setup_possible_cpus = -1;
-static int __init _setup_possible_cpus(char *str)
-{
- get_option(&str, &setup_possible_cpus);
- return 0;
-}
-early_param("possible_cpus", _setup_possible_cpus);
-
-
-/*
- * cpu_possible_mask should be static, it cannot change as cpu's
- * are onlined, or offlined. The reason is per-cpu data-structures
- * are allocated by some modules at init time, and don't expect to
- * do this dynamically on cpu arrival/departure.
- * cpu_present_mask on the other hand can change dynamically.
- * In case when cpu_hotplug is not compiled, then we resort to current
- * behaviour, which is cpu_possible == cpu_present.
- * - Ashok Raj
- *
- * Three ways to find out the number of additional hotplug CPUs:
- * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
- * - The user can overwrite it with possible_cpus=NUM
- * - Otherwise don't reserve additional CPUs.
- * We do this because additional CPUs waste a lot of memory.
- * -AK
- */
-__init void prefill_possible_map(void)
-{
- int i, possible;
-
- i = setup_max_cpus ?: 1;
- if (setup_possible_cpus == -1) {
- possible = num_processors;
-#ifdef CONFIG_HOTPLUG_CPU
- if (setup_max_cpus)
- possible += disabled_cpus;
-#else
- if (possible > i)
- possible = i;
-#endif
- } else
- possible = setup_possible_cpus;
-
- total_cpus = max_t(int, possible, num_processors + disabled_cpus);
-
- /* nr_cpu_ids could be reduced via nr_cpus= */
- if (possible > nr_cpu_ids) {
- pr_warn("%d Processors exceeds NR_CPUS limit of %u\n",
- possible, nr_cpu_ids);
- possible = nr_cpu_ids;
- }
-
-#ifdef CONFIG_HOTPLUG_CPU
- if (!setup_max_cpus)
-#endif
- if (possible > i) {
- pr_warn("%d Processors exceeds max_cpus limit of %u\n",
- possible, setup_max_cpus);
- possible = i;
- }
-
- set_nr_cpu_ids(possible);
-
- pr_info("Allowing %d CPUs, %d hotplug CPUs\n",
- possible, max_t(int, possible - num_processors, 0));
-
- reset_cpu_possible_mask();
-
- for (i = 0; i < possible; i++)
- set_cpu_possible(i, true);
-}
-
/* correctly size the local cpu masks */
void __init setup_cpu_local_masks(void)
{