intel-iommu: Disallow interrupt remapping if not all ioapics covered

Current kernel enable interrupt remapping only when all the vt-d unit support
interrupt remapping. So it is reasonable we should also disallow enabling
intr-remapping if there any io-apics that are not listed under vt-d units.
Otherwise we can run into issues.

Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 5 insertions, 3 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 3264b626725a..fba4f6891680 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -570,9 +570,6 @@ int __init dmar_table_init(void)
                 printk(KERN_INFO PREFIX "No ATSR found\n");
 #endif
 
-#ifdef CONFIG_INTR_REMAP
-        parse_ioapics_under_ir();
-#endif
         return 0;
 }
 
diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index 4f5b8712931f..ebfa47b79c5b 100644
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -626,6 +626,11 @@ int __init enable_intr_remapping(int eim)
         struct dmar_drhd_unit *drhd;
         int setup = 0;
 
+        if (parse_ioapics_under_ir() != 1) {
+                printk(KERN_INFO "Not enable interrupt remapping\n");
+                return -1;
+        }
+
         for_each_drhd_unit(drhd) {
                 struct intel_iommu *iommu = drhd->iommu;