x86/apic/x2apic: Implement IPI shorthands support

All callers of apic->send_IPI_all() and apic->send_IPI_allbutself() contain
the decision logic for shorthand invocation already and invoke
send_IPI_mask() if the prereqisites are not satisfied.

Implement shorthand support for x2apic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105221.134696837@linutronix.de

arch/x86/kernel/apic/local.h

@@ -23,6 +23,7 @@ unsigned int x2apic_get_apic_id(unsigned long id);
 u32 x2apic_set_apic_id(unsigned int id);
 int x2apic_phys_pkg_id(int initial_apicid, int index_msb);
 void x2apic_send_IPI_self(int vector);
+void __x2apic_send_IPI_shorthand(int vector, u32 which);
 
 /* IPI */
 

arch/x86/kernel/apic/x2apic_cluster.c

@@ -82,12 +82,12 @@ x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector)
 
 static void x2apic_send_IPI_allbutself(int vector)
 {
-	__x2apic_send_IPI_mask(cpu_online_mask, vector, APIC_DEST_ALLBUT);
+	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLBUT);
 }
 
 static void x2apic_send_IPI_all(int vector)
 {
-	__x2apic_send_IPI_mask(cpu_online_mask, vector, APIC_DEST_ALLINC);
+	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLINC);
 }
 
 static u32 x2apic_calc_apicid(unsigned int cpu)

arch/x86/kernel/apic/x2apic_phys.c

@@ -75,12 +75,12 @@ static void
 
 static void x2apic_send_IPI_allbutself(int vector)
 {
-	__x2apic_send_IPI_mask(cpu_online_mask, vector, APIC_DEST_ALLBUT);
+	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLBUT);
 }
 
 static void x2apic_send_IPI_all(int vector)
 {
-	__x2apic_send_IPI_mask(cpu_online_mask, vector, APIC_DEST_ALLINC);
+	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLINC);
 }
 
 static void init_x2apic_ldr(void)
@@ -112,6 +112,14 @@ void __x2apic_send_IPI_dest(unsigned int apicid, int vector, unsigned int dest)
 	native_x2apic_icr_write(cfg, apicid);
 }
 
+void __x2apic_send_IPI_shorthand(int vector, u32 which)
+{
+	unsigned long cfg = __prepare_ICR(which, vector, 0);
+
+	x2apic_wrmsr_fence();
+	native_x2apic_icr_write(cfg, 0);
+}
+
 unsigned int x2apic_get_apic_id(unsigned long id)
 {
 	return id;