1 files changed, 24 insertions, 2 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 3a0428e8435..c850de4c9a1 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -173,8 +173,30 @@ int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id)
         apic_id = map_mat_entry(handle, type, acpi_id);
         if (apic_id == -1)
                 apic_id = map_madt_entry(type, acpi_id);
-        if (apic_id == -1)
-                return apic_id;
+        if (apic_id == -1) {
+                /*
+                 * On UP processor, there is no _MAT or MADT table.
+                 * So above apic_id is always set to -1.
+                 *
+                 * BIOS may define multiple CPU handles even for UP processor.
+                 * For example,
+                 *
+                 * Scope (_PR)
+                 * {
+                 *     Processor (CPU0, 0x00, 0x00000410, 0x06) {}
+                 *     Processor (CPU1, 0x01, 0x00000410, 0x06) {}
+                 *     Processor (CPU2, 0x02, 0x00000410, 0x06) {}
+                 *     Processor (CPU3, 0x03, 0x00000410, 0x06) {}
+                 * }
+                 *
+                 * Ignores apic_id and always return 0 for CPU0's handle.
+                 * Return -1 for other CPU's handle.
+                 */
+                if (acpi_id == 0)
+                        return acpi_id;
+                else
+                        return apic_id;
+        }
 
 #ifdef CONFIG_SMP
         for_each_possible_cpu(i) {