1 files changed, 11 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/mpparse.c b/arch/x86_64/kernel/mpparse.c
index b17cf3eba359..083da7e606b1 100644
--- a/arch/x86_64/kernel/mpparse.c
+++ b/arch/x86_64/kernel/mpparse.c
@@ -968,7 +968,17 @@ int mp_register_gsi(u32 gsi, int triggering, int polarity)
                  */
                 int irq = gsi;
                 if (gsi < MAX_GSI_NUM) {
-                        if (gsi > 15)
+                        /*
+                         * Retain the VIA chipset work-around (gsi > 15), but
+                         * avoid a problem where the 8254 timer (IRQ0) is setup
+                         * via an override (so it's not on pin 0 of the ioapic),
+                         * and at the same time, the pin 0 interrupt is a PCI
+                         * type.  The gsi > 15 test could cause these two pins
+                         * to be shared as IRQ0, and they are not shareable.
+                         * So test for this condition, and if necessary, avoid
+                         * the pin collision.
+                         */
+                        if (gsi > 15 || (gsi == 0 && !timer_uses_ioapic_pin_0))
                                 gsi = pci_irq++;
                         /*
                          * Don't assign IRQ used by ACPI SCI