[PATCH] x86_64: Memorize location of i8259 for reboots.

Currently we attempt to restore virtual wire mode on reboot, which only
works if we can figure out where the i8259 is connected. This is very
useful when we are kexec another kernel and likely helpful to an peculiar
BIOS that make assumptions about how the system is setup.

Since the acpi MADT table does not provide the location where the i8259 is
connected we have to look at the hardware to figure it out.

Most systems have the i8259 connected the local apic of the cpu so won't be
affected but people running Opteron and some serverworks chipsets should be
able to use kexec now.

In addition this patch removes the hard coded assumption that the io_apic
that delivers isa interrups is always known to the kernel as io_apic 0.
There does not appear to be anything to guarantee that assumption is true.

And From: Vivek Goyal <[e-mail]>

A minor fix to the patch which remembers the location of where i8259 is
connected. Now counter i has been replaced by apic. counter i is having
some junk value which was leading to non-detection of i8259 connected to
IOAPIC.

Signed-off-by: Eric W. Biederman <[e-mail]>
Signed-off-by: Vivek Goyal <[e-mail]>
Signed-off-by: Andi Kleen <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/i386/kernel/io_apic.c

···
 	for(apic = 0; apic < nr_ioapics; apic++) {
 		int pin;
 		/* See if any of the pins is in ExtINT mode */
-		for(pin = 0; pin < nr_ioapic_registers[i]; pin++) {
+		for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
 			struct IO_APIC_route_entry entry;
 			spin_lock_irqsave(&ioapic_lock, flags);
 			*(((int *)&entry) + 0) = io_apic_read(apic, 0x10 + 2 * pin);

arch/x86_64/kernel/io_apic.c

···
 
 int disable_timer_pin_1 __initdata;
 
+/* Where if anywhere is the i8259 connect in external int mode */
+static struct { int pin, apic; } ioapic_i8259 = { -1, -1 };
+
 static DEFINE_SPINLOCK(ioapic_lock);
 
 /*
···
 /*
  * Find the pin to which IRQ[irq] (ISA) is connected
  */
-static int find_isa_irq_pin(int irq, int type)
+static int __init find_isa_irq_pin(int irq, int type)
 {
 	int i;
 
···
 
 			return mp_irqs[i].mpc_dstirq;
 	}
+	return -1;
+}
+
+static int __init find_isa_irq_apic(int irq, int type)
+{
+	int i;
+
+	for (i = 0; i < mp_irq_entries; i++) {
+		int lbus = mp_irqs[i].mpc_srcbus;
+
+		if ((mp_bus_id_to_type[lbus] == MP_BUS_ISA ||
+		     mp_bus_id_to_type[lbus] == MP_BUS_EISA ||
+		     mp_bus_id_to_type[lbus] == MP_BUS_MCA) &&
+		    (mp_irqs[i].mpc_irqtype == type) &&
+		    (mp_irqs[i].mpc_srcbusirq == irq))
+			break;
+	}
+	if (i < mp_irq_entries) {
+		int apic;
+		for(apic = 0; apic < nr_ioapics; apic++) {
+			if (mp_ioapics[apic].mpc_apicid == mp_irqs[i].mpc_dstapic)
+				return apic;
+		}
+	}
+
 	return -1;
 }
 
···
  * Set up the 8259A-master output pin as broadcast to all
  * CPUs.
  */
-static void __init setup_ExtINT_IRQ0_pin(unsigned int pin, int vector)
+static void __init setup_ExtINT_IRQ0_pin(unsigned int apic, unsigned int pin, int vector)
 {
 	struct IO_APIC_route_entry entry;
 	unsigned long flags;
···
 	 * Add it to the IO-APIC irq-routing table:
 	 */
 	spin_lock_irqsave(&ioapic_lock, flags);
-	io_apic_write(0, 0x11+2*pin, *(((int *)&entry)+1));
-	io_apic_write(0, 0x10+2*pin, *(((int *)&entry)+0));
+	io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
+	io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
 	spin_unlock_irqrestore(&ioapic_lock, flags);
 
 	enable_8259A_irq(0);
···
 static void __init enable_IO_APIC(void)
 {
 	union IO_APIC_reg_01 reg_01;
-	int i;
+	int i8259_apic, i8259_pin;
+	int i, apic;
 	unsigned long flags;
 
 	for (i = 0; i < PIN_MAP_SIZE; i++) {
···
 	/*
 	 * The number of IO-APIC IRQ registers (== #pins):
 	 */
-	for (i = 0; i < nr_ioapics; i++) {
+	for (apic = 0; apic < nr_ioapics; apic++) {
 		spin_lock_irqsave(&ioapic_lock, flags);
-		reg_01.raw = io_apic_read(i, 1);
+		reg_01.raw = io_apic_read(apic, 1);
 		spin_unlock_irqrestore(&ioapic_lock, flags);
-		nr_ioapic_registers[i] = reg_01.bits.entries+1;
+		nr_ioapic_registers[apic] = reg_01.bits.entries+1;
+	}
+	for(apic = 0; apic < nr_ioapics; apic++) {
+		int pin;
+		/* See if any of the pins is in ExtINT mode */
+		for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
+			struct IO_APIC_route_entry entry;
+			spin_lock_irqsave(&ioapic_lock, flags);
+			*(((int *)&entry) + 0) = io_apic_read(apic, 0x10 + 2 * pin);
+			*(((int *)&entry) + 1) = io_apic_read(apic, 0x11 + 2 * pin);
+			spin_unlock_irqrestore(&ioapic_lock, flags);
+
+
+			/* If the interrupt line is enabled and in ExtInt mode
+			 * I have found the pin where the i8259 is connected.
+			 */
+			if ((entry.mask == 0) && (entry.delivery_mode == dest_ExtINT)) {
+				ioapic_i8259.apic = apic;
+				ioapic_i8259.pin  = pin;
+				goto found_i8259;
+			}
+		}
+	}
+ found_i8259:
+	/* Look to see what if the MP table has reported the ExtINT */
+	i8259_pin  = find_isa_irq_pin(0, mp_ExtINT);
+	i8259_apic = find_isa_irq_apic(0, mp_ExtINT);
+	/* Trust the MP table if nothing is setup in the hardware */
+	if ((ioapic_i8259.pin == -1) && (i8259_pin >= 0)) {
+		printk(KERN_WARNING "ExtINT not setup in hardware but reported by MP table\n");
+		ioapic_i8259.pin  = i8259_pin;
+		ioapic_i8259.apic = i8259_apic;
+	}
+	/* Complain if the MP table and the hardware disagree */
+	if (((ioapic_i8259.apic != i8259_apic) || (ioapic_i8259.pin != i8259_pin)) &&
+		(i8259_pin >= 0) && (ioapic_i8259.pin >= 0))
+	{
+		printk(KERN_WARNING "ExtINT in hardware and MP table differ\n");
 	}
 
 	/*
···
  */
 void disable_IO_APIC(void)
 {
-	int pin;
 	/*
 	 * Clear the IO-APIC before rebooting:
 	 */
···
 	 * Put that IOAPIC in virtual wire mode
 	 * so legacy interrupts can be delivered.
 	 */
-	pin = find_isa_irq_pin(0, mp_ExtINT);
-	if (pin != -1) {
+	if (ioapic_i8259.pin != -1) {
 		struct IO_APIC_route_entry entry;
 		unsigned long flags;
 
···
 		entry.polarity        = 0; /* High */
 		entry.delivery_status = 0;
 		entry.dest_mode       = 0; /* Physical */
-		entry.delivery_mode   = 7; /* ExtInt */
+		entry.delivery_mode   = dest_ExtINT; /* ExtInt */
 		entry.vector          = 0;
 		entry.dest.physical.physical_dest = 0;
-
 
 		/*
 		 * Add it to the IO-APIC irq-routing table:
 		 */
 		spin_lock_irqsave(&ioapic_lock, flags);
-		io_apic_write(0, 0x11+2*pin, *(((int *)&entry)+1));
-		io_apic_write(0, 0x10+2*pin, *(((int *)&entry)+0));
+		io_apic_write(ioapic_i8259.apic, 0x11+2*ioapic_i8259.pin,
+			*(((int *)&entry)+1));
+		io_apic_write(ioapic_i8259.apic, 0x10+2*ioapic_i8259.pin,
+			*(((int *)&entry)+0));
 		spin_unlock_irqrestore(&ioapic_lock, flags);
 	}
 
-	disconnect_bsp_APIC(pin != -1);
+	disconnect_bsp_APIC(ioapic_i8259.pin != -1);
 }
 
 /*
···
  */
 static inline void unlock_ExtINT_logic(void)
 {
-	int pin, i;
+	int apic, pin, i;
 	struct IO_APIC_route_entry entry0, entry1;
 	unsigned char save_control, save_freq_select;
 	unsigned long flags;
 
-	pin = find_isa_irq_pin(8, mp_INT);
+	pin  = find_isa_irq_pin(8, mp_INT);
+	apic = find_isa_irq_apic(8, mp_INT);
 	if (pin == -1)
 		return;
 
 	spin_lock_irqsave(&ioapic_lock, flags);
-	*(((int *)&entry0) + 1) = io_apic_read(0, 0x11 + 2 * pin);
-	*(((int *)&entry0) + 0) = io_apic_read(0, 0x10 + 2 * pin);
+	*(((int *)&entry0) + 1) = io_apic_read(apic, 0x11 + 2 * pin);
+	*(((int *)&entry0) + 0) = io_apic_read(apic, 0x10 + 2 * pin);
 	spin_unlock_irqrestore(&ioapic_lock, flags);
-	clear_IO_APIC_pin(0, pin);
+	clear_IO_APIC_pin(apic, pin);
 
 	memset(&entry1, 0, sizeof(entry1));
 
···
 	entry1.vector = 0;
 
 	spin_lock_irqsave(&ioapic_lock, flags);
-	io_apic_write(0, 0x11 + 2 * pin, *(((int *)&entry1) + 1));
-	io_apic_write(0, 0x10 + 2 * pin, *(((int *)&entry1) + 0));
+	io_apic_write(apic, 0x11 + 2 * pin, *(((int *)&entry1) + 1));
+	io_apic_write(apic, 0x10 + 2 * pin, *(((int *)&entry1) + 0));
 	spin_unlock_irqrestore(&ioapic_lock, flags);
 
 	save_control = CMOS_READ(RTC_CONTROL);
···
 
 	CMOS_WRITE(save_control, RTC_CONTROL);
 	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
-	clear_IO_APIC_pin(0, pin);
+	clear_IO_APIC_pin(apic, pin);
 
 	spin_lock_irqsave(&ioapic_lock, flags);
-	io_apic_write(0, 0x11 + 2 * pin, *(((int *)&entry0) + 1));
-	io_apic_write(0, 0x10 + 2 * pin, *(((int *)&entry0) + 0));
+	io_apic_write(apic, 0x11 + 2 * pin, *(((int *)&entry0) + 1));
+	io_apic_write(apic, 0x10 + 2 * pin, *(((int *)&entry0) + 0));
 	spin_unlock_irqrestore(&ioapic_lock, flags);
 }
 
···
  */
 static inline void check_timer(void)
 {
-	int pin1, pin2;
+	int apic1, pin1, apic2, pin2;
 	int vector;
 
 	/*
···
 	init_8259A(1);
 	enable_8259A_irq(0);
 
-	pin1 = find_isa_irq_pin(0, mp_INT);
-	pin2 = find_isa_irq_pin(0, mp_ExtINT);
+	pin1  = find_isa_irq_pin(0, mp_INT);
+	apic1 = find_isa_irq_apic(0, mp_INT);
+	pin2  = ioapic_i8259.pin;
+	apic2 = ioapic_i8259.apic;
 
-	apic_printk(APIC_VERBOSE,KERN_INFO "..TIMER: vector=0x%02X pin1=%d pin2=%d\n", vector, pin1, pin2);
+	apic_printk(APIC_VERBOSE,KERN_INFO "..TIMER: vector=0x%02X apic1=%d pin1=%d apic2=%d pin2=%d\n",
+		vector, apic1, pin1, apic2, pin2);
 
 	if (pin1 != -1) {
 		/*
···
 				clear_IO_APIC_pin(0, pin1);
 			return;
 		}
-		clear_IO_APIC_pin(0, pin1);
-		apic_printk(APIC_QUIET,KERN_ERR "..MP-BIOS bug: 8254 timer not connected to IO-APIC\n");
+		clear_IO_APIC_pin(apic1, pin1);
+		apic_printk(APIC_QUIET,KERN_ERR "..MP-BIOS bug: 8254 timer not "
+				"connected to IO-APIC\n");
 	}
 
-	apic_printk(APIC_VERBOSE,KERN_INFO "...trying to set up timer (IRQ0) through the 8259A ... ");
+	apic_printk(APIC_VERBOSE,KERN_INFO "...trying to set up timer (IRQ0) "
+				"through the 8259A ... ");
 	if (pin2 != -1) {
-		apic_printk(APIC_VERBOSE,"\n..... (found pin %d) ...", pin2);
+		apic_printk(APIC_VERBOSE,"\n..... (found apic %d pin %d) ...",
+			apic2, pin2);
 		/*
 		 * legacy devices should be connected to IO APIC #0
 		 */
-		setup_ExtINT_IRQ0_pin(pin2, vector);
+		setup_ExtINT_IRQ0_pin(apic2, pin2, vector);
 		if (timer_irq_works()) {
 			printk("works.\n");
 			nmi_watchdog_default();
···
 		/*
 		 * Cleanup, just in case ...
 		 */
-		clear_IO_APIC_pin(0, pin2);
+		clear_IO_APIC_pin(apic2, pin2);
 	}
 	printk(" failed.\n");