By default CONFIG_INTEL_IOMMU_DEFAULT_ON is not set and thus
dmar_disabled variable is set.
Intel IOMMU driver based on above doesn't set intel_iommu_enabled
variable.
The commit b0119e8708 ("iommu: Introduce new 'struct iommu_device'")
mistakenly assumes it never happens and tries to unregister not ever
registered resources, which crashes the kernel at boot time:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: iommu_device_unregister+0x31/0x60
Make unregister procedure conditional in free_iommu().
Fixes: b0119e8708 ("iommu: Introduce new 'struct iommu_device'")
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
c37a01779b