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Message-ID: <20240118123649.513878058@linutronix.de>
From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org,
 Tom Lendacky <thomas.lendacky@amd.com>,
 Andrew Cooper <andrew.cooper3@citrix.com>,
 Arjan van de Ven <arjan@linux.intel.com>,
 Huang Rui <ray.huang@amd.com>,
 Juergen Gross <jgross@suse.com>,
 Dimitri Sivanich <dimitri.sivanich@hpe.com>,
 Sohil Mehta <sohil.mehta@intel.com>,
 K Prateek Nayak <kprateek.nayak@amd.com>,
 Kan Liang <kan.liang@linux.intel.com>,
 Zhang Rui <rui.zhang@intel.com>,
 "Paul E. McKenney" <paulmck@kernel.org>,
 Feng Tang <feng.tang@intel.com>,
 Andy Shevchenko <andy@infradead.org>,
 Michael Kelley <mhklinux@outlook.com>,
 "Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [patch v2 17/30] x86/cpu/topology: Reject unknown APIC IDs on ACPI
 hotplug
References: <20240118123127.055361964@linutronix.de>
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Date: Tue, 23 Jan 2024 14:11:17 +0100 (CET)

From: Thomas Gleixner <tglx@linutronix.de>

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>

---
 arch/x86/kernel/cpu/topology.c |    4 ++++
 1 file changed, 4 insertions(+)
---
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -266,6 +266,10 @@ int topology_hotplug_apic(u32 apic_id, u
 	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)