x86/lguest: Do not setup unused irq vectors

No point in assigning the interrupt vectors if there is no interrupt
chip installed. Move it to lguest_setup_irq() and call it from
lguest_enable_irq.

[ rusty: Typo fix and error handling ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Link: http://lkml.kernel.org/r/1438662776-4823-2-git-send-email-rusty@rustcorp.com.au
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 13 insertions, 9 deletions

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index d933a11ceba6..2165f45befff 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -850,21 +850,29 @@ static int lguest_setup_irq(unsigned int irq)
         if (err < 0 && err != -EEXIST)
                 return err;
 
+        /*
+         * Tell the Linux infrastructure that the interrupt is
+         * controlled by our level-based lguest interrupt controller.
+         */
         irq_set_chip_and_handler_name(irq, &lguest_irq_controller,
                                       handle_level_irq, "level");
+
+        /* Some systems map "vectors" to interrupts weirdly.  Not us! */
+        __this_cpu_write(vector_irq[FIRST_EXTERNAL_VECTOR + irq], irq);
         return 0;
 }
 
 static int lguest_enable_irq(struct pci_dev *dev)
 {
+        int err;
         u8 line = 0;
 
         /* We literally use the PCI interrupt line as the irq number. */
         pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &line);
-        irq_set_chip_and_handler_name(line, &lguest_irq_controller,
-                                      handle_level_irq, "level");
-        dev->irq = line;
-        return 0;
+        err = lguest_setup_irq(line);
+        if (!err)
+                dev->irq = line;
+        return err;
 }
 
 /* We don't do hotplug PCI, so this shouldn't be called. */
@@ -875,17 +883,13 @@ static void lguest_disable_irq(struct pci_dev *dev)
 
 /*
  * This sets up the Interrupt Descriptor Table (IDT) entry for each hardware
- * interrupt (except 128, which is used for system calls), and then tells the
- * Linux infrastructure that each interrupt is controlled by our level-based
- * lguest interrupt controller.
+ * interrupt (except 128, which is used for system calls).
  */
 static void __init lguest_init_IRQ(void)
 {
         unsigned int i;
 
         for (i = FIRST_EXTERNAL_VECTOR; i < FIRST_SYSTEM_VECTOR; i++) {
-                /* Some systems map "vectors" to interrupts weirdly.  Not us! */
-                __this_cpu_write(vector_irq[i], i - FIRST_EXTERNAL_VECTOR);
                 if (i != IA32_SYSCALL_VECTOR)
                         set_intr_gate(i, irq_entries_start +
                                         8 * (i - FIRST_EXTERNAL_VECTOR));