[PATCH] x86/apic: Fix xen failure caused by commit b81975eade8c

[Jiang Liu]

Commit b81975eade8c "x86, irq: Clean up irqdomain transition code"
breaks Xen because xen_smp_prepare_cpus() doesn't call setup_IO_APIC()
so mp_map_pin_to_irq() fails at the very beginning.

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/hw_irq.h        |    2 +-
 arch/x86/include/asm/smpboot_hooks.h |    6 +++---
 arch/x86/kernel/apic/apic.c          |    6 +++---
 arch/x86/kernel/apic/io_apic.c       |   32 +++++++++++++++-----------------
 arch/x86/xen/smp.c                   |    3 +++
 5 files changed, 25 insertions(+), 24 deletions(-)

diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index 4615906d83df..0c6530dfd817 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -98,7 +98,7 @@ extern void trace_call_function_single_interrupt(void);
 #define IO_APIC_IRQ(x) (((x) >= NR_IRQS_LEGACY) || ((1<<(x)) & io_apic_irqs))
 extern unsigned long io_apic_irqs;
 
-extern void setup_IO_APIC(void);
+extern void setup_IO_APIC(bool xen_smp);
 extern void disable_IO_APIC(void);
 
 struct io_apic_irq_attr {
diff --git a/arch/x86/include/asm/smpboot_hooks.h b/arch/x86/include/asm/smpboot_hooks.h
index 0da7409f0bec..76e5731b03cb 100644
--- a/arch/x86/include/asm/smpboot_hooks.h
+++ b/arch/x86/include/asm/smpboot_hooks.h
@@ -52,9 +52,9 @@ static inline void __init smpboot_setup_io_apic(void)
 	 * Here we can be sure that there is an IO-APIC in the system. Let's
 	 * go and set it up:
 	 */
-	if (!skip_ioapic_setup && nr_ioapics)
-		setup_IO_APIC();
-	else {
+	if (!skip_ioapic_setup && nr_ioapics) {
+		setup_IO_APIC(false);
+	} else {
 		nr_ioapics = 0;
 	}
 #endif
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ba6cc041edb1..33ba1f97abea 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1912,9 +1912,9 @@ int __init APIC_init_uniprocessor(void)
 	bsp_end_local_APIC_setup();
 
 #ifdef CONFIG_X86_IO_APIC
-	if (smp_found_config && !skip_ioapic_setup && nr_ioapics)
-		setup_IO_APIC();
-	else {
+	if (smp_found_config && !skip_ioapic_setup && nr_ioapics) {
+		setup_IO_APIC(false);
+	} else {
 		nr_ioapics = 0;
 	}
 #endif
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index a6745e756729..5879ac58c3b6 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2965,31 +2965,29 @@ static int mp_irqdomain_create(int ioapic)
 	return 0;
 }
 
-void __init setup_IO_APIC(void)
+void __init setup_IO_APIC(bool xen_smp)
 {
 	int ioapic;
 
-	/*
-	 * calling enable_IO_APIC() is moved to setup_local_APIC for BP
-	 */
-	io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
+	if (!xen_smp) {
+		apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
+		io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
+
+		/* Set up IO-APIC IRQ routing. */
+		x86_init.mpparse.setup_ioapic_ids();
+		sync_Arb_IDs();
+	}
 
-	apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
 	for_each_ioapic(ioapic)
 		BUG_ON(mp_irqdomain_create(ioapic));
-
-	/*
-         * Set up IO-APIC IRQ routing.
-         */
-	x86_init.mpparse.setup_ioapic_ids();
-
-	sync_Arb_IDs();
 	setup_IO_APIC_irqs();
-	init_IO_APIC_traps();
-	if (nr_legacy_irqs())
-		check_timer();
-
 	ioapic_initialized = 1;
+
+	if (!xen_smp) {
+		init_IO_APIC_traps();
+		if (nr_legacy_irqs())
+			check_timer();
+	}
 }
 
 /*
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 4c071aeb8417..7eb0283901fa 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -326,7 +326,10 @@ static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
 
 		xen_raw_printk(m);
 		panic(m);
+	} else {
+		setup_IO_APIC(true);
 	}
+
 	xen_init_lock_cpu(0);
 
 	smp_store_boot_cpu_info();
-- 
1.7.10.4


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