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>

3 files changed, 47 insertions, 4 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 932e5e3930fc..f1805002e436 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -982,7 +982,7 @@ static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
 }
 
 #define PRIMARY_FAULT_REG_LEN (16)
-static irqreturn_t dmar_fault(int irq, void *dev_id)
+irqreturn_t dmar_fault(int irq, void *dev_id)
 {
         struct intel_iommu *iommu = dev_id;
         int reg, fault_index;
@@ -1074,9 +1074,6 @@ int dmar_set_interrupt(struct intel_iommu *iommu)
                 return 0;
         }
 
-        /* Force fault register is cleared */
-        dmar_fault(irq, iommu);
-
         ret = request_irq(irq, dmar_fault, 0, iommu->name, iommu);
         if (ret)
                 printk(KERN_ERR "IOMMU: can't request irq\n");
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
diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index 0d202d73a1ac..a84686b2478b 100644
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -499,6 +499,23 @@ int __init enable_intr_remapping(int eim)
         struct dmar_drhd_unit *drhd;
         int setup = 0;
 
+        for_each_drhd_unit(drhd) {
+                struct intel_iommu *iommu = drhd->iommu;
+
+                /*
+                 * Clear previous faults.
+                 */
+                dmar_fault(-1, iommu);
+
+                /*
+                 * Disable intr remapping and queued invalidation, if already
+                 * enabled prior to OS handover.
+                 */
+                disable_intr_remapping(iommu);
+
+                dmar_disable_qi(iommu);
+        }
+
         /*
          * check for the Interrupt-remapping support
          */