x86, dmar: check if it's initialized before disable queue invalidation

If queue invalidation is disabled after it's already initialized,
dmar_enable_qi won't re-enable it due to iommu->qi is allocated.
It may result in system hang when use queue invalidation. Add this
check to avoid this case.

Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index ef25caade54b..472be1c3fff0 100644
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -524,6 +524,13 @@ int __init enable_intr_remapping(int eim)
                 struct intel_iommu *iommu = drhd->iommu;
 
                 /*
+                 * If the queued invalidation is already initialized,
+                 * shouldn't disable it.
+                 */
+                if (iommu->qi)
+                        continue;
+
+                /*
                  * Clear previous faults.
                  */
                 dmar_fault(-1, iommu);