[patch 33/53] x86/cpu/topology: Use a data structure for topology info

Thomas Gleixner
2023-08-07T13:54:48Z

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>
---
arch/x86/kernel/cpu/topology.c | 59 ++++++++++++++++++++---------------------
1 file changed, 29 insertions(+), 30 deletions(-)

--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -23,25 +23,24 @@ DECLARE_BITMAP(phys_cpu_present_map, MAX
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.
+ */
+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
* avoid undefined behaviour caused by sending INIT from AP to BSP.
*/
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_threa
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 ap
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 ap
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_cpu
*/
__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 a
}

if (!present) {
- disabled_cpus++;
+ topo_info.nr_disabled_cpus++;
return;
}

@@ -295,7 +295,6 @@ void topology_hotunplug_apic(unsigned in
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