[PATCH 1/2] ns16550: reject IRQ above nr_irqs

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

Intel LPSS has INTERRUPT_LINE set to 0xff by default, that can't
possibly work. While a proper IRQ configuration may be useful,
validating value retrieved from the hardware is still necessary. If it
fails, use the device in poll mode.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
---
 xen/drivers/char/ns16550.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index e5b4a9085516..2d7c8c11bc69 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -1221,6 +1221,9 @@ pci_uart_config(struct ns16550 *uart, bool_t skip_amt, unsigned int idx)
                             pci_conf_read8(PCI_SBDF(0, b, d, f),
                                            PCI_INTERRUPT_LINE) : 0;
 
+                if (uart->irq >= nr_irqs)
+                    uart->irq = 0;
+
                 return 0;
             }
         }
-- 
2.31.1