1 files changed, 55 insertions, 15 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index d313039e2fdf..3fbe6af7ad71 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -790,14 +790,41 @@ end:
 }
 
 /*
+ * Enable queued invalidation.
+ */
+static void __dmar_enable_qi(struct intel_iommu *iommu)
+{
+        u32 cmd, sts;
+        unsigned long flags;
+        struct q_inval *qi = iommu->qi;
+
+        qi->free_head = qi->free_tail = 0;
+        qi->free_cnt = QI_LENGTH;
+
+        spin_lock_irqsave(&iommu->register_lock, flags);
+
+        /* write zero to the tail reg */
+        writel(0, iommu->reg + DMAR_IQT_REG);
+
+        dmar_writeq(iommu->reg + DMAR_IQA_REG, virt_to_phys(qi->desc));
+
+        cmd = iommu->gcmd | DMA_GCMD_QIE;
+        iommu->gcmd |= DMA_GCMD_QIE;
+        writel(cmd, iommu->reg + DMAR_GCMD_REG);
+
+        /* Make sure hardware complete it */
+        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG, readl, (sts & DMA_GSTS_QIES), sts);
+
+        spin_unlock_irqrestore(&iommu->register_lock, flags);
+}
+
+/*
  * Enable Queued Invalidation interface. This is a must to support
  * interrupt-remapping. Also used by DMA-remapping, which replaces
  * register based IOTLB invalidation.
  */
 int dmar_enable_qi(struct intel_iommu *iommu)
 {
-        u32 cmd, sts;
-        unsigned long flags;
         struct q_inval *qi;
 
         if (!ecap_qis(iommu->ecap))
@@ -835,19 +862,7 @@ int dmar_enable_qi(struct intel_iommu *iommu)
 
         spin_lock_init(&qi->q_lock);
 
-        spin_lock_irqsave(&iommu->register_lock, flags);
-        /* write zero to the tail reg */
-        writel(0, iommu->reg + DMAR_IQT_REG);
-
-        dmar_writeq(iommu->reg + DMAR_IQA_REG, virt_to_phys(qi->desc));
-
-        cmd = iommu->gcmd | DMA_GCMD_QIE;
-        iommu->gcmd |= DMA_GCMD_QIE;
-        writel(cmd, iommu->reg + DMAR_GCMD_REG);
-
-        /* Make sure hardware complete it */
-        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG, readl, (sts & DMA_GSTS_QIES), sts);
-        spin_unlock_irqrestore(&iommu->register_lock, flags);
+        __dmar_enable_qi(iommu);
 
         return 0;
 }
@@ -1102,3 +1117,28 @@ int __init enable_drhd_fault_handling(void)
 
         return 0;
 }
+
+/*
+ * Re-enable Queued Invalidation interface.
+ */
+int dmar_reenable_qi(struct intel_iommu *iommu)
+{
+        if (!ecap_qis(iommu->ecap))
+                return -ENOENT;
+
+        if (!iommu->qi)
+                return -ENOENT;
+
+        /*
+         * First disable queued invalidation.
+         */
+        dmar_disable_qi(iommu);
+        /*
+         * Then enable queued invalidation again. Since there is no pending
+         * invalidation requests now, it's safe to re-enable queued
+         * invalidation.
+         */
+        __dmar_enable_qi(iommu);
+
+        return 0;
+}