x86/cpu/topology: Use a data structure for topology info

Put the processor accounting into a data structure, which will gain more
topology related information in the next steps, and sanitize the accounting.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20240213210252.111451909@linutronix.de

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 8b42918b7b582b9ff31ec5b91e626d1581dfe439..815e3eeed41593d4691738f6d17d5a602d16a758 100644 (file)
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -22,6 +22,18 @@ DECLARE_BITMAP(phys_cpu_present_map, MAX_LOCAL_APIC) __read_mostly;
 /* Used for CPU number allocation and parallel CPU bringup */
 u32 cpuid_to_apicid[] __read_mostly = { [0 ... NR_CPUS - 1] = BAD_APICID, };
 
+/*
+ * Keep track of assigned, disabled and rejected CPUs. Present assigned
+ * with 1 as CPU #0 is reserved for the boot CPU.
+ */
+static struct {
+       unsigned int            nr_assigned_cpus;
+       unsigned int            nr_disabled_cpus;
+       unsigned int            nr_rejected_cpus;
+} topo_info __read_mostly = {
+       .nr_assigned_cpus       = 1,
+};
+
 /*
  * Processor to be disabled specified by kernel parameter
  * disable_cpu_apicid=<int>, mostly used for the kdump 2nd kernel to
@@ -29,19 +41,6 @@ u32 cpuid_to_apicid[] __read_mostly = { [0 ... NR_CPUS - 1] = BAD_APICID, };
  */
 static u32 disabled_cpu_apicid __ro_after_init = BAD_APICID;
 
-static unsigned int num_processors;
-static unsigned int disabled_cpus;
-
-/*
- * The number of allocated logical CPU IDs. Since logical CPU IDs are allocated
- * contiguously, it equals to current allocated max logical CPU ID plus 1.
- * All allocated CPU IDs should be in the [0, nr_logical_cpuids) range,
- * so the maximum of nr_logical_cpuids is nr_cpu_ids.
- *
- * NOTE: Reserve 0 for BSP.
- */
-static int nr_logical_cpuids = 1;
-
 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 {
        return phys_id == (u64)cpuid_to_apicid[cpu];
@@ -75,7 +74,7 @@ static int __init smp_init_primary_thread_mask(void)
                return 0;
        }
 
-       for (cpu = 0; cpu < nr_logical_cpuids; cpu++)
+       for (cpu = 0; cpu < topo_info.nr_assigned_cpus; cpu++)
                cpu_mark_primary_thread(cpu, cpuid_to_apicid[cpu]);
        return 0;
 }
@@ -89,7 +88,7 @@ static int topo_lookup_cpuid(u32 apic_id)
        int i;
 
        /* CPU# to APICID mapping is persistent once it is established */
-       for (i = 0; i < nr_logical_cpuids; i++) {
+       for (i = 0; i < topo_info.nr_assigned_cpus; i++) {
                if (cpuid_to_apicid[i] == apic_id)
                        return i;
        }
@@ -107,22 +106,21 @@ static int allocate_logical_cpuid(u32 apic_id)
        if (cpu >= 0)
                return cpu;
 
-       cpuid_to_apicid[nr_logical_cpuids] = apic_id;
-       return nr_logical_cpuids++;
+       return topo_info.nr_assigned_cpus++;
 }
 
-static void cpu_update_apic(int cpu, u32 apicid)
+static void cpu_update_apic(unsigned int cpu, u32 apic_id)
 {
 #if defined(CONFIG_SMP) || defined(CONFIG_X86_64)
-       early_per_cpu(x86_cpu_to_apicid, cpu) = apicid;
+       early_per_cpu(x86_cpu_to_apicid, cpu) = apic_id;
 #endif
+       cpuid_to_apicid[cpu] = apic_id;
        set_cpu_possible(cpu, true);
-       set_bit(apicid, phys_cpu_present_map);
+       set_bit(apic_id, phys_cpu_present_map);
        set_cpu_present(cpu, true);
-       num_processors++;
 
        if (system_state != SYSTEM_BOOTING)
-               cpu_mark_primary_thread(cpu, apicid);
+               cpu_mark_primary_thread(cpu, apic_id);
 }
 
 static int generic_processor_info(int apicid)
@@ -137,18 +135,18 @@ static int generic_processor_info(int apicid)
                return 0;
 
        if (disabled_cpu_apicid == apicid) {
-               int thiscpu = num_processors + disabled_cpus;
+               int thiscpu = topo_info.nr_assigned_cpus + topo_info.nr_disabled_cpus;
 
                pr_warn("APIC: Disabling requested cpu. Processor %d/0x%x ignored.\n",
                        thiscpu, apicid);
 
-               disabled_cpus++;
+               topo_info.nr_rejected_cpus++;
                return -ENODEV;
        }
 
-       if (num_processors >= nr_cpu_ids) {
+       if (topo_info.nr_assigned_cpus >= nr_cpu_ids) {
                pr_warn_once("APIC: CPU limit of %d reached. Ignoring further CPUs\n", nr_cpu_ids);
-               disabled_cpus++;
+               topo_info.nr_rejected_cpus++;
                return -ENOSPC;
        }
 
@@ -178,14 +176,16 @@ static int __initdata setup_possible_cpus = -1;
  */
 __init void prefill_possible_map(void)
 {
+       unsigned int num_processors = topo_info.nr_assigned_cpus;
+       unsigned int disabled_cpus = topo_info.nr_disabled_cpus;
        int i, possible;
 
        i = setup_max_cpus ?: 1;
        if (setup_possible_cpus == -1) {
-               possible = num_processors;
+               possible = topo_info.nr_assigned_cpus;
 #ifdef CONFIG_HOTPLUG_CPU
                if (setup_max_cpus)
-                       possible += disabled_cpus;
+                       possible += num_processors;
 #else
                if (possible > i)
                        possible = i;
@@ -238,7 +238,7 @@ void __init topology_register_apic(u32 apic_id, u32 acpi_id, bool present)
        }
 
        if (!present) {
-               disabled_cpus++;
+               topo_info.nr_disabled_cpus++;
                return;
        }
 
@@ -295,7 +295,6 @@ void topology_hotunplug_apic(unsigned int cpu)
        per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
        clear_bit(apic_id, phys_cpu_present_map);
        set_cpu_present(cpu, false);
-       num_processors--;
 }
 #endif