[Qemu-devel] [PATCH] intel_iommu: Return error on machines with no PCI

[Mohammed Gamal <mgamal@redhat.com>]

Starting the following command line causes a segfault
qemu-system-x86_64 -S -machine isapc,accel=kvm -device intel-iommu

This is due to the fact that the machine type 'isapc' doesn't have
a PCI bus, while intel_iommu doesn't check if the machine has PCI support
and subsequently does a null-pointer access. Intel IOMMU shouldn't even work
if the target machine doesn't have PCI.

Add a check for PCI on the given machine type and return an error if PCI
is not supported.

Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
---
 hw/i386/intel_iommu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 3a5bb0b..fab0b4b 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3041,6 +3041,13 @@ static void vtd_realize(DeviceState *dev, Error **errp)
     }
 
     bus = pcms->bus;
+
+    if (!bus) {
+        error_setg(errp, "Machine-type '%s' does not support PCI",
+                   mc->name);
+        return;
+    }
+
     x86_iommu->type = TYPE_INTEL;
 
     if (!vtd_decide_config(s, errp)) {
-- 
1.8.3.1