powerpc/pci: Fix regression in powerpc MSI-X

Patch f598282f5145036312d90875d0ed5c14b49fd8a7 exposed a problem in
powerpc MSI-X functionality, making network interfaces such as ixgbe
and cxgb3 stop to work when MSI-X is enabled. RX interrupts were not
being generated.

The problem was caused because MSI irq was not being effectively
unmasked after device initialization.

Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/xics.c b/arch/powerpc/platforms/pseries/xics.c
index 419f8a637ffe..b9bf0eedccf2 100644
--- a/arch/powerpc/platforms/pseries/xics.c
+++ b/arch/powerpc/platforms/pseries/xics.c
@@ -18,6 +18,7 @@
 #include <linux/init.h>
 #include <linux/radix-tree.h>
 #include <linux/cpu.h>
+#include <linux/msi.h>
 #include <linux/of.h>
 
 #include <asm/firmware.h>
@@ -219,6 +220,14 @@ static void xics_unmask_irq(unsigned int virq)
 
 static unsigned int xics_startup(unsigned int virq)
 {
+        /*
+         * The generic MSI code returns with the interrupt disabled on the
+         * card, using the MSI mask bits. Firmware doesn't appear to unmask
+         * at that level, so we do it here by hand.
+         */
+        if (irq_to_desc(virq)->msi_desc)
+                unmask_msi_irq(virq);
+
         /* unmask it */
         xics_unmask_irq(virq);
         return 0;