[PATCH] x86/IRQ: bump max number of guests for a shared IRQ to 31

[Igor Druzhinin <igor.druzhinin@citrix.com>]

Current limit of 7 is too restrictive for modern systems where one GSI
could be shared by potentially many PCI INTx sources where each of them
corresponds to a device passed through to its own guest. Some systems do not
apply due dilligence in swizzling INTx links in case e.g. INTA is declared as
interrupt pin for the majority of PCI devices behind a single router,
resulting in overuse of a GSI.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
---

If people think that would make sense - I can rework the array to a list of
domain pointers to avoid the limit.

---
 xen/arch/x86/irq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 8d1f9a9..194f660 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1028,7 +1028,7 @@ int __init setup_irq(unsigned int irq, unsigned int irqflags,
  * HANDLING OF GUEST-BOUND PHYSICAL IRQS
  */
 
-#define IRQ_MAX_GUESTS 7
+#define IRQ_MAX_GUESTS 31
 typedef struct {
     u8 nr_guests;
     u8 in_flight;
-- 
2.7.4