x86, ACPI, irq: Fix possible eror in GSI to IRQ mapping for legacy IRQ

A default identity mapping between GSI and IRQ is built for legacy IRQs.
So when overriding the default identity mapping for legacy IRQs,
we should also invalidate isa_irq_to_gsi[gsi] when setting
isa_irq_to_gsi[irq] = gsi.  Otherwise there may be two entries with the
same GSI in the isa_irq_to_gsi array, and acpi_isa_irq_to_gsi() may give
wrong result.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Link: http://lkml.kernel.org/r/1402302011-23642-10-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 298f79616f1c..f3bafcd32b98 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -366,6 +366,13 @@ static void __init mp_override_legacy_irq(u8 bus_irq, u8 polarity, u8 trigger,
 
         mp_save_irq(&mp_irq);
 
+        /*
+         * Reset default identity mapping if gsi is also an legacy IRQ,
+         * otherwise there will be more than one entry with the same GSI
+         * and acpi_isa_irq_to_gsi() may give wrong result.
+         */
+        if (gsi < NR_IRQS_LEGACY && isa_irq_to_gsi[gsi] == gsi)
+                isa_irq_to_gsi[gsi] = ACPI_INVALID_GSI;
         isa_irq_to_gsi[bus_irq] = gsi;
 }
 
@@ -621,7 +628,8 @@ EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
 
 int acpi_isa_irq_to_gsi(unsigned isa_irq, u32 *gsi)
 {
-        if (isa_irq < NR_IRQS_LEGACY) {
+        if (isa_irq < NR_IRQS_LEGACY &&
+            isa_irq_to_gsi[isa_irq] != ACPI_INVALID_GSI) {
                 *gsi = isa_irq_to_gsi[isa_irq];
                 return 0;
         }