x86/apic: Fix signedness bug in APIC ID validity checks

The APIC ID as parsed from ACPI MADT is validity checked with the
apic->apic_id_valid() callback, which depends on the selected APIC type.

For non X2APIC types APIC IDs >= 0xFF are invalid, but values > 0x7FFFFFFF
are detected as valid. This happens because the 'apicid' argument of the
apic_id_valid() callback is type 'int'. So the resulting comparison

apicid < 0xFF

evaluates to true for all unsigned int values > 0x7FFFFFFF which are handed
to default_apic_id_valid(). As a consequence, invalid APIC IDs in !X2APIC
mode are considered valid and accounted as possible CPUs.

Change the apicid argument type of the apic_id_valid() callback to u32 so
the evaluation is unsigned and returns the correct result.

[ tglx: Massaged changelog ]

Signed-off-by: Li RongQing <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: Dou Liyang <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Link: https://lkml.kernel.org/r/[e-mail]

arch/x86/include/asm/apic.h

···
 	/* Probe, setup and smpboot functions */
 	int	(*probe)(void);
 	int	(*acpi_madt_oem_check)(char *oem_id, char *oem_table_id);
-	int	(*apic_id_valid)(int apicid);
+	int	(*apic_id_valid)(u32 apicid);
 	int	(*apic_id_registered)(void);
 
 	bool	(*check_apicid_used)(physid_mask_t *map, int apicid);
···
 	return apic->get_apic_id(reg);
 }
 
-extern int default_apic_id_valid(int apicid);
+extern int default_apic_id_valid(u32 apicid);
 extern int default_acpi_madt_oem_check(char *, char *);
 extern void default_setup_apic_routing(void);
 

arch/x86/kernel/acpi/boot.c

···
 {
 	struct acpi_madt_local_x2apic *processor = NULL;
 #ifdef CONFIG_X86_X2APIC
-	int apic_id;
+	u32 apic_id;
 	u8 enabled;
 #endif
 
···
 	 * to not preallocating memory for all NR_CPUS
 	 * when we use CPU hotplug.
 	 */
-	if (!apic->apic_id_valid(apic_id) && enabled)
-		printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
-	else
-		acpi_register_lapic(apic_id, processor->uid, enabled);
+	if (!apic->apic_id_valid(apic_id)) {
+		if (enabled)
+			pr_warn(PREFIX "x2apic entry ignored\n");
+		return 0;
+	}
+
+	acpi_register_lapic(apic_id, processor->uid, enabled);
 #else
 	printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
 #endif

arch/x86/kernel/apic/apic_common.c

···
 	return physid_isset(phys_apicid, phys_cpu_present_map);
 }
 
-int default_apic_id_valid(int apicid)
+int default_apic_id_valid(u32 apicid)
 {
 	return (apicid < 255);
 }

arch/x86/kernel/apic/apic_numachip.c

···
 	return id << 24;
 }
 
-static int numachip_apic_id_valid(int apicid)
+static int numachip_apic_id_valid(u32 apicid)
 {
 	/* Trust what bootloader passes in MADT */
 	return 1;

arch/x86/kernel/apic/x2apic.h

···
 /* Common bits for X2APIC cluster/physical modes. */
 
-int x2apic_apic_id_valid(int apicid);
+int x2apic_apic_id_valid(u32 apicid);
 int x2apic_apic_id_registered(void);
 void __x2apic_send_IPI_dest(unsigned int apicid, int vector, unsigned int dest);
 unsigned int x2apic_get_apic_id(unsigned long id);

arch/x86/kernel/apic/x2apic_phys.c

···
 }
 
 /* Common x2apic functions, also used by x2apic_cluster */
-int x2apic_apic_id_valid(int apicid)
+int x2apic_apic_id_valid(u32 apicid)
 {
 	return 1;
 }

arch/x86/kernel/apic/x2apic_uv_x.c

···
 	uv_send_IPI_mask(cpu_online_mask, vector);
 }
 
-static int uv_apic_id_valid(int apicid)
+static int uv_apic_id_valid(u32 apicid)
 {
 	return 1;
 }

arch/x86/xen/apic.c

···
 	return xen_pv_domain();
 }
 
-static int xen_id_always_valid(int apicid)
+static int xen_id_always_valid(u32 apicid)
 {
 	return 1;
 }