iommu/vt-d: Don't disable IR when it was previously enabled

Keep it enabled in kdump kernel to guarantee interrupt
delivery.

Tested-by: ZhenHua Li <zhen-hual@hp.com>
Tested-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 14e10de4a548..47fcebf39e9e 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -742,9 +742,6 @@ static int __init intel_prepare_irq_remapping(void)
                         pr_info("%s does not support EIM\n", iommu->name);
                         eim = 0;
                 }
-
-                /* Disable IRQ remapping if it is already enabled */
-                iommu_disable_irq_remapping(iommu);
         }
 
         eim_mode = eim;
@@ -777,7 +774,8 @@ static int __init intel_enable_irq_remapping(void)
          * Setup Interrupt-remapping for all the DRHD's now.
          */
         for_each_iommu(iommu, drhd) {
-                iommu_enable_irq_remapping(iommu);
+                if (!ir_pre_enabled(iommu))
+                        iommu_enable_irq_remapping(iommu);
                 setup = true;
         }