[tip: x86/apic] x86/cpu/topology: Reject unknown APIC IDs on ACPI hotplug

["tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>]

The following commit has been merged into the x86/apic branch of tip:

Commit-ID:     7cdcdab1a660bbe9f98bf1591c048ce7ccee59e0
Gitweb:        https://git.kernel.org/tip/7cdcdab1a660bbe9f98bf1591c048ce7ccee59e0
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Tue, 13 Feb 2024 22:05:57 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 15 Feb 2024 22:07:43 +01:00

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



---
 arch/x86/kernel/cpu/topology.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index c671206..a6d045b 100644
--- 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)