x86/apic: Simplify X2APIC ID validation

Currently, x2apic_max_apicid==0 means that there is no max APIC id limit.
But, this means that 0 needs to be special-cased.

Designate UINT_MAX to mean unlimited so that a plain old less than or equal
compare works and there is no special-casing.  Replace the 0 initialization
with UINT_MAX.

[ dhansen: muck with changelog ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)

diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index d6495acaf6afc354e2a2bdb046749d5f30e4bef5..d292ec311c19258e37b834d3748aace8095bcac3 100644 (file)
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -8,7 +8,7 @@
 int x2apic_phys;
 
 static struct apic apic_x2apic_phys;
-static u32 x2apic_max_apicid __ro_after_init;
+static u32 x2apic_max_apicid __ro_after_init = UINT_MAX;
 
 void __init x2apic_set_max_apicid(u32 apicid)
 {
@@ -125,10 +125,7 @@ static int x2apic_phys_probe(void)
 /* Common x2apic functions, also used by x2apic_cluster */
 int x2apic_apic_id_valid(u32 apicid)
 {
-       if (x2apic_max_apicid && apicid > x2apic_max_apicid)
-               return 0;
-
-       return 1;
+       return apicid <= x2apic_max_apicid;
 }
 
 unsigned int x2apic_get_apic_id(unsigned long id)