On Thu, Sep 14, 2017 at 05:31:38PM -0300, Eduardo Habkost wrote: > On Thu, Sep 14, 2017 at 10:24:23PM +0200, Thomas Huth wrote: > > 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. > > I agree this would be much simpler.
Even, shall we move the pcms && bus check into x86_iommu_realize() directly? Then we will only need one single patch for Intel/AMD, and it's also a cleanup. Thanks, -- Peter Xu