x86/apic: Move safe wait_icr_idle() next to apic_mem_wait_icr_idle()

Move it next to apic_mem_wait_icr_idle(), rename it so that it's clear what
it does and rewrite it in readable form.
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)

arch/x86/include/asm/apic.h

@@ -98,7 +98,6 @@ static inline u32 native_apic_mem_read(u32 reg)
 	return *((volatile u32 *)(APIC_BASE + reg));
 }
 
-extern u32 native_safe_apic_wait_icr_idle(void);
 extern void native_apic_icr_write(u32 low, u32 id);
 extern u64 native_apic_icr_read(void);
 

arch/x86/kernel/apic/apic.c

@@ -240,23 +240,6 @@ static void __init apic_disable(void)
 	apic = &apic_noop;
 }
 
-u32 native_safe_apic_wait_icr_idle(void)
-{
-	u32 send_status;
-	int timeout;
-
-	timeout = 0;
-	do {
-		send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
-		if (!send_status)
-			break;
-		inc_irq_stat(icr_read_retry_count);
-		udelay(100);
-	} while (timeout++ < 1000);
-
-	return send_status;
-}
-
 void native_apic_icr_write(u32 low, u32 id)
 {
 	unsigned long flags;

arch/x86/kernel/apic/apic_flat_64.c

@@ -112,7 +112,7 @@ static struct apic apic_flat __ro_after_init = {
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= apic_mem_wait_icr_idle,
-	.safe_wait_icr_idle		= native_safe_apic_wait_icr_idle,
+	.safe_wait_icr_idle		= apic_mem_wait_icr_idle_timeout,
 };
 
 /*
@@ -188,7 +188,7 @@ static struct apic apic_physflat __ro_after_init = {
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= apic_mem_wait_icr_idle,
-	.safe_wait_icr_idle		= native_safe_apic_wait_icr_idle,
+	.safe_wait_icr_idle		= apic_mem_wait_icr_idle_timeout,
 };
 
 /*

arch/x86/kernel/apic/bigsmp_32.c

@@ -109,7 +109,7 @@ static struct apic apic_bigsmp __ro_after_init = {
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= apic_mem_wait_icr_idle,
-	.safe_wait_icr_idle		= native_safe_apic_wait_icr_idle,
+	.safe_wait_icr_idle		= apic_mem_wait_icr_idle_timeout,
 };
 
 bool __init apic_bigsmp_possible(bool cmdline_override)

arch/x86/kernel/apic/ipi.c

 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/cpumask.h>
+#include <linux/delay.h>
 #include <linux/smp.h>
+
 #include <asm/io_apic.h>
 
 #include "local.h"
@@ -102,6 +104,19 @@ static inline int __prepare_ICR2(unsigned int mask)
 	return SET_XAPIC_DEST_FIELD(mask);
 }
 
+u32 apic_mem_wait_icr_idle_timeout(void)
+{
+	int cnt;
+
+	for (cnt = 0; cnt < 1000; cnt++) {
+		if (!(apic_read(APIC_ICR) & APIC_ICR_BUSY))
+			return 0;
+		inc_irq_stat(icr_read_retry_count);
+		udelay(100);
+	}
+	return APIC_ICR_BUSY;
+}
+
 void apic_mem_wait_icr_idle(void)
 {
 	while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY)
@@ -135,7 +150,7 @@ static void __default_send_IPI_shortcut(unsigned int shortcut, int vector)
 	 * to stop the others before launching the kdump kernel.
 	 */
 	if (unlikely(vector == NMI_VECTOR))
-		safe_apic_wait_icr_idle();
+		apic_mem_wait_icr_idle_timeout();
 	else
 		apic_mem_wait_icr_idle();
 
@@ -152,7 +167,7 @@ void __default_send_IPI_dest_field(unsigned int dest_mask, int vector,
 {
 	/* See comment in __default_send_IPI_shortcut() */
 	if (unlikely(vector == NMI_VECTOR))
-		safe_apic_wait_icr_idle();
+		apic_mem_wait_icr_idle_timeout();
 	else
 		apic_mem_wait_icr_idle();
 

arch/x86/kernel/apic/local.h

@@ -45,6 +45,7 @@ static inline unsigned int __prepare_ICR(unsigned int shortcut, int vector,
 void default_init_apic_ldr(void);
 
 void apic_mem_wait_icr_idle(void);
+u32 apic_mem_wait_icr_idle_timeout(void);
 
 /*
  * This is used to send an IPI with no shorthand notation (the destination is

arch/x86/kernel/apic/probe_32.c

@@ -65,7 +65,7 @@ static struct apic apic_default __ro_after_init = {
 	.icr_read			= native_apic_icr_read,
 	.icr_write			= native_apic_icr_write,
 	.wait_icr_idle			= apic_mem_wait_icr_idle,
-	.safe_wait_icr_idle		= native_safe_apic_wait_icr_idle,
+	.safe_wait_icr_idle		= apic_mem_wait_icr_idle_timeout,
 };
 
 apic_driver(apic_default);