From c37a01779b3954d9c8f9ac4f663a03c11f69fded Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Wed, 15 Feb 2017 16:42:21 +0200
Subject: 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 b0119e870837 ("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: b0119e870837 ("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>
---
drivers/iommu/dmar.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index d9c0decfc91a..36e3f430d265 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -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) {
--
cgit