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iommu/vt-d: Fix crash on boot when DMAR is disabled 

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>
This commit is contained in:
Andy Shevchenko 2017-02-15 16:42:21 +02:00 committed by Joerg Roedel
parent ebb4949eb3
commit c37a01779b
1 changed files with 4 additions and 2 deletions
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6
drivers/iommu/dmar.c
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@ -1108,8 +1108,10 @@ error:
static void free_iommu(struct intel_iommu *iommu)
{
iommu_device_sysfs_remove(&iommu->iommu);
iommu_device_unregister(&iommu->iommu);
if (intel_iommu_enabled) {
iommu_device_unregister(&iommu->iommu);
iommu_device_sysfs_remove(&iommu->iommu);
}
if (iommu->irq) {
if (iommu->pr_irq) {