From e1d78452d411c039a84eb32243a6f5ce45e4feae Mon Sep 17 00:00:00 2001
From: jdolecek <jdolecek@NetBSD.org>
Date: Wed, 17 Jun 2020 14:04:03 +0000
Subject: [PATCH] explicitly disable INTx interrupts to avoid interrupt storm
 triggered by unhandled adapter interrupts

fixes PR kern/46596 by Andreas Gustafsson, fix adopted from FreeBSD
---
 sys/dev/pci/vga_pci.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/sys/dev/pci/vga_pci.c b/sys/dev/pci/vga_pci.c
index a726270238c6..93e84b8fa72d 100644
--- a/sys/dev/pci/vga_pci.c
+++ b/sys/dev/pci/vga_pci.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: vga_pci.c,v 1.55 2016/07/07 06:55:41 msaitoh Exp $	*/
+/*	$NetBSD: vga_pci.c,v 1.56 2020/06/17 14:04:03 jdolecek Exp $	*/
 
 /*
  * Copyright (c) 1995, 1996 Carnegie-Mellon University.
@@ -28,7 +28,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vga_pci.c,v 1.55 2016/07/07 06:55:41 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vga_pci.c,v 1.56 2020/06/17 14:04:03 jdolecek Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -230,6 +230,16 @@ vga_pci_attach(device_t parent, device_t self, void *aux)
 			    "WARNING: strange BAR @ 0x%02x\n", reg);
 	}
 
+	/*
+	 * Disable INTx interrupts, there is no specific chipset driver for
+	 * this PCI device. Else unhandled display adapter interrupts
+	 * might freeze the CPU.
+	 */
+	pcireg_t cmd  = pci_conf_read(pa->pa_pc, pa->pa_tag,
+	    PCI_COMMAND_STATUS_REG);
+	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
+	    cmd | PCI_COMMAND_INTERRUPT_DISABLE);
+
 	/* XXX Expansion ROM? */
 
 	vga_common_attach(sc, pa->pa_iot, pa->pa_memt, WSDISPLAY_TYPE_PCIVGA,