From d98e19ccef10c5aadccc4ffe2925e4099ff9606a Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Sun, 30 Oct 2011 15:16:58 +0100
Subject: [PATCH] [S390] smp: external call vs. emergency signal

Use a sigp sense running to decide which signal processor order to use
for an ipi. If the target cpu is running use external call, if the target
cpu is not running use emergency signal.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/kernel/head31.S |  2 +-
 arch/s390/kernel/head64.S |  2 +-
 arch/s390/kernel/smp.c    | 12 +++++++++++-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kernel/head31.S b/arch/s390/kernel/head31.S
index f21954b44dc1..d3f1ab7d90ad 100644
--- a/arch/s390/kernel/head31.S
+++ b/arch/s390/kernel/head31.S
@@ -92,7 +92,7 @@ ENTRY(_stext)
 .LPG3:
 # check control registers
 	stctl	%c0,%c15,0(%r15)
-	oi	2(%r15),0x40		# enable sigp emergency signal
+	oi	2(%r15),0x60		# enable sigp emergency & external call
 	oi	0(%r15),0x10		# switch on low address protection
 	lctl	%c0,%c15,0(%r15)
 
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index ae5d492b069e..99348c0eaa41 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -90,7 +90,7 @@ ENTRY(_stext)
 .LPG3:
 # check control registers
 	stctg	%c0,%c15,0(%r15)
-	oi	6(%r15),0x40		# enable sigp emergency signal
+	oi	6(%r15),0x60		# enable sigp emergency & external call
 	oi	4(%r15),0x10		# switch on low address proctection
 	lctlg	%c0,%c15,0(%r15)
 
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 6c8a977af595..3bde5688ceb5 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -209,12 +209,19 @@ static void do_ext_call_interrupt(unsigned int ext_int_code,
  */
 static void smp_ext_bitcall(int cpu, int sig)
 {
+	int order;
+
 	/*
 	 * Set signaling bit in lowcore of target cpu and kick it
 	 */
 	set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
-	while (sigp(cpu, sigp_emergency_signal) == sigp_busy)
+	while (1) {
+		order = smp_vcpu_scheduled(cpu) ?
+			sigp_external_call : sigp_emergency_signal;
+		if (sigp(cpu, order) != sigp_busy)
+			break;
 		udelay(10);
+	}
 }
 
 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
@@ -754,6 +761,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	/* request the 0x1201 emergency signal external interrupt */
 	if (register_external_interrupt(0x1201, do_ext_call_interrupt) != 0)
 		panic("Couldn't request external interrupt 0x1201");
+	/* request the 0x1202 external call external interrupt */
+	if (register_external_interrupt(0x1202, do_ext_call_interrupt) != 0)
+		panic("Couldn't request external interrupt 0x1202");
 
 	/* Reallocate current lowcore, but keep its contents. */
 	lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);