1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 23a119e6485e..bd2c01674f5e 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -457,6 +457,31 @@ void __init detect_intel_iommu(void)
 
 #ifdef CONFIG_DMAR
         {
+                struct acpi_table_dmar *dmar;
+                /*
+                 * for now we will disable dma-remapping when interrupt
+                 * remapping is enabled.
+                 * When support for queued invalidation for IOTLB invalidation
+                 * is added, we will not need this any more.
+                 */
+                dmar = (struct acpi_table_dmar *) dmar_tbl;
+                if (ret && cpu_has_x2apic && dmar->flags & 0x1) {
+                        printk(KERN_INFO
+                               "Queued invalidation will be enabled to support "
+                               "x2apic and Intr-remapping.\n");
+                        printk(KERN_INFO
+                               "Disabling IOMMU detection, because of missing "
+                               "queued invalidation support for IOTLB "
+                               "invalidation\n");
+                        printk(KERN_INFO
+                               "Use \"nox2apic\", if you want to use Intel "
+                               " IOMMU for DMA-remapping and don't care about "
+                               " x2apic support\n");
+
+                        dmar_disabled = 1;
+                        return;
+                }
+
                 if (ret && !no_iommu && !iommu_detected && !swiotlb &&
                     !dmar_disabled)
                         iommu_detected = 1;