From a0c167a18470831e359f0538c3cf67907808f13e Mon Sep 17 00:00:00 2001
From: Mohammed Gamal <mgamal@redhat.com>
Date: Wed, 29 Nov 2017 13:33:13 +0100
Subject: [PATCH] x86_iommu: check if machine has PCI bus

Starting qemu with
qemu-system-x86_64 -S -M isapc -device {amd|intel}-iommu
leads to a segfault. The code assume PCI bus is present and
tries to access the bus structure without checking.

Since Intel VT-d and AMDVI should only work with PCI, add a
check for PCI bus and return error if not present.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 hw/i386/x86-iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c
index 51de519ec3..8a01a2dd25 100644
--- a/hw/i386/x86-iommu.c
+++ b/hw/i386/x86-iommu.c
@@ -88,7 +88,7 @@ static void x86_iommu_realize(DeviceState *dev, Error **errp)
         PC_MACHINE(object_dynamic_cast(OBJECT(ms), TYPE_PC_MACHINE));
     QLIST_INIT(&x86_iommu->iec_notifiers);
 
-    if (!pcms) {
+    if (!pcms || !pcms->bus) {
         error_setg(errp, "Machine-type '%s' not supported by IOMMU",
                    mc->name);
         return;