1 files changed, 57 insertions, 3 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index a8c94bb6b528..2dc01c38ad8e 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2021,7 +2021,53 @@ void disconnect_bsp_APIC(int virt_wire_setup)
 	apic_write(APIC_LVT1, value);
 }
 
-static int __generic_processor_info(int apicid, int version, bool enabled)
+/*
+ * 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 ID should be in [0, nr_logical_cpuidi), so the maximum of
+ * nr_logical_cpuids is nr_cpu_ids.
+ *
+ * NOTE: Reserve 0 for BSP.
+ */
+static int nr_logical_cpuids = 1;
+
+/*
+ * Used to store mapping between logical CPU IDs and APIC IDs.
+ */
+static int cpuid_to_apicid[] = {
+	[0 ... NR_CPUS - 1] = -1,
+};
+
+/*
+ * Should use this API to allocate logical CPU IDs to keep nr_logical_cpuids
+ * and cpuid_to_apicid[] synchronized.
+ */
+static int allocate_logical_cpuid(int apicid)
+{
+	int i;
+
+	/*
+	 * cpuid <-> apicid mapping is persistent, so when a cpu is up,
+	 * check if the kernel has allocated a cpuid for it.
+	 */
+	for (i = 0; i < nr_logical_cpuids; i++) {
+		if (cpuid_to_apicid[i] == apicid)
+			return i;
+	}
+
+	/* Allocate a new cpuid. */
+	if (nr_logical_cpuids >= nr_cpu_ids) {
+		WARN_ONCE(1, "Only %d processors supported."
+			     "Processor %d/0x%x and the rest are ignored.\n",
+			     nr_cpu_ids - 1, nr_logical_cpuids, apicid);
+		return -1;
+	}
+
+	cpuid_to_apicid[nr_logical_cpuids] = apicid;
+	return nr_logical_cpuids++;
+}
+
+int __generic_processor_info(int apicid, int version, bool enabled)
 {
 	int cpu, max = nr_cpu_ids;
 	bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid,
@@ -2096,8 +2142,16 @@ static int __generic_processor_info(int apicid, int version, bool enabled)
 		 * for BSP.
 		 */
 		cpu = 0;
-	} else
-		cpu = cpumask_next_zero(-1, cpu_present_mask);
+
+		/* Logical cpuid 0 is reserved for BSP. */
+		cpuid_to_apicid[0] = apicid;
+	} else {
+		cpu = allocate_logical_cpuid(apicid);
+		if (cpu < 0) {
+			disabled_cpus++;
+			return -EINVAL;
+		}
+	}
 
 	/*
 	 * This can happen on physical hotplug. The sanity check at boot time