On 14.09.2017 22:18, Mohammed Gamal wrote: > Starting the following command line causes a segfault > qemu-system-x86_64 -S -machine isapc,accel=kvm -device amd-iommu > > This is due to the fact that the machine type 'isapc' doesn't have > a PCI bus, while amd_iommu doesn't check if the machine has PCI support > and subsequently does a null-pointer access. AMD 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 <mga...@redhat.com> > --- > hw/i386/amd_iommu.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c > index 334938a..9a667b7 100644 > --- a/hw/i386/amd_iommu.c > +++ b/hw/i386/amd_iommu.c > @@ -1153,6 +1153,13 @@ static void amdvi_realize(DeviceState *dev, Error > **err) > } > > bus = pcms->bus; > + > + if (!bus) { > + error_setg(err, "Machine-type '%s' does not support PCI", > + mc->name); > + return; > + } > + > s->iotlb = g_hash_table_new_full(amdvi_uint64_hash, > amdvi_uint64_equal, g_free, g_free); > >
Patch looks fine to me, but I think it would also be sufficient to change the check at the beginning of the function to test "if (!pcms || !pcms->bus)" instead of just "if (!pcms)" ... the error message "Machine-type 'xxx' not supported by amd-iommu" is also adequate if there is no PCI bus available on the system. Thomas