Comment 24 for bug 1838575

Reference:
this is the call from qemu that I think we see above (on x86) is at [1].
If this time the assumption is correct the kernel place would be at vfio_iommu_type1_ioctl.

For debugging:
$ gdb qemu/x86_64-softmmu/qemu-system-x86_64
(gdb) catch syscall 16
(gdb) run -m 131072 -smp 1 -no-user-config -device vfio-pci,host=21:00.1,id=hostdev0,bus=pci.0,addr=0x7
(gdb) continue 22
# Now we are "in front" of the bad call.

https://git.qemu.org/?p=qemu.git;a=blob;f=hw/vfio/common.c;h=3e03c495d868f154b26a33c0c2d870273a0b4198;hb=HEAD#l480