x86, dmar: start with sane state while enabling dma and interrupt-remapping

Impact: cleanup/sanitization

Start from a sane state while enabling dma and interrupt-remapping, by
clearing the previous recorded faults and disabling previously
enabled queued invalidation and interrupt-remapping.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 25fc1df486bb..ef167b8b047d 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -1855,11 +1855,40 @@ static int __init init_dmars(void)
                 }
         }
 
+        /*
+         * Start from the sane iommu hardware state.
+         */
         for_each_drhd_unit(drhd) {
                 if (drhd->ignored)
                         continue;
 
                 iommu = drhd->iommu;
+
+                /*
+                 * If the queued invalidation is already initialized by us
+                 * (for example, while enabling interrupt-remapping) then
+                 * we got the things already rolling from a sane state.
+                 */
+                if (iommu->qi)
+                        continue;
+
+                /*
+                 * Clear any previous faults.
+                 */
+                dmar_fault(-1, iommu);
+                /*
+                 * Disable queued invalidation if supported and already enabled
+                 * before OS handover.
+                 */
+                dmar_disable_qi(iommu);
+        }
+
+        for_each_drhd_unit(drhd) {
+                if (drhd->ignored)
+                        continue;
+
+                iommu = drhd->iommu;
+
                 if (dmar_enable_qi(iommu)) {
                         /*
                          * Queued Invalidate not enabled, use Register Based