x86/cpu/topology: Reject unknown APIC IDs on ACPI hotplug

The topology bitmaps track all possible APIC IDs which have been registered
during enumeration. As sizing and further topology information is going to
be derived from these bitmaps, reject attempts to hotplug an APIC ID which
was not registered during enumeration.

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/20240213210252.462231229@linutronix.de

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index c67120657e55628c48b59b6e8fc582e0a0857c7c..a6d045b15ebdc066e1fd26ae009dbaf921532ccd 100644 (file)
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -272,6 +272,10 @@ int topology_hotplug_apic(u32 apic_id, u32 acpi_id)
        if (apic_id >= MAX_LOCAL_APIC)
                return -EINVAL;
 
+       /* Reject if the APIC ID was not registered during enumeration. */
+       if (!test_bit(apic_id, apic_maps[TOPO_SMT_DOMAIN].map))
+               return -ENODEV;
+
        cpu = topo_lookup_cpuid(apic_id);
        if (cpu < 0) {
                if (topo_info.nr_assigned_cpus >= nr_cpu_ids)