return -ENOMEM;
 
        iommu->seq_id = iommu_allocated++;
+       sprintf (iommu->name, "dmar%d", iommu->seq_id);
 
        iommu->reg = ioremap(drhd->reg_base_addr, VTD_PAGE_SIZE);
        if (!iommu->reg) {
 
 /* iommu interrupt handling. Most stuff are MSI-like. */
 
-static const char *fault_reason_strings[] =
+enum faulttype {
+       DMA_REMAP,
+       INTR_REMAP,
+       UNKNOWN,
+};
+
+static const char *dma_remap_fault_reasons[] =
 {
        "Software",
        "Present bit in root entry is clear",
        "non-zero reserved fields in CTP",
        "non-zero reserved fields in PTE",
 };
+
+static const char *intr_remap_fault_reasons[] =
+{
+       "Detected reserved fields in the decoded interrupt-remapped request",
+       "Interrupt index exceeded the interrupt-remapping table size",
+       "Present field in the IRTE entry is clear",
+       "Error accessing interrupt-remapping table pointed by IRTA_REG",
+       "Detected reserved fields in the IRTE entry",
+       "Blocked a compatibility format interrupt request",
+       "Blocked an interrupt request due to source-id verification failure",
+};
+
 #define MAX_FAULT_REASON_IDX   (ARRAY_SIZE(fault_reason_strings) - 1)
 
-const char *dmar_get_fault_reason(u8 fault_reason)
+const char *dmar_get_fault_reason(u8 fault_reason, int *fault_type)
 {
-       if (fault_reason > MAX_FAULT_REASON_IDX)
+       if (fault_reason >= 0x20 && (fault_reason <= 0x20 +
+                                    ARRAY_SIZE(intr_remap_fault_reasons))) {
+               *fault_type = INTR_REMAP;
+               return intr_remap_fault_reasons[fault_reason - 0x20];
+       } else if (fault_reason < ARRAY_SIZE(dma_remap_fault_reasons)) {
+               *fault_type = DMA_REMAP;
+               return dma_remap_fault_reasons[fault_reason];
+       } else {
+               *fault_type = UNKNOWN;
                return "Unknown";
-       else
-               return fault_reason_strings[fault_reason];
+       }
 }
 
 void dmar_msi_unmask(unsigned int irq)
                u8 fault_reason, u16 source_id, unsigned long long addr)
 {
        const char *reason;
+       int fault_type;
 
-       reason = dmar_get_fault_reason(fault_reason);
+       reason = dmar_get_fault_reason(fault_reason, &fault_type);
 
-       printk(KERN_ERR
-               "DMAR:[%s] Request device [%02x:%02x.%d] "
-               "fault addr %llx \n"
-               "DMAR:[fault reason %02d] %s\n",
-               (type ? "DMA Read" : "DMA Write"),
-               (source_id >> 8), PCI_SLOT(source_id & 0xFF),
-               PCI_FUNC(source_id & 0xFF), addr, fault_reason, reason);
+       if (fault_type == INTR_REMAP)
+               printk(KERN_ERR "INTR-REMAP: Request device [[%02x:%02x.%d] "
+                      "fault index %llx\n"
+                       "INTR-REMAP:[fault reason %02d] %s\n",
+                       (source_id >> 8), PCI_SLOT(source_id & 0xFF),
+                       PCI_FUNC(source_id & 0xFF), addr >> 48,
+                       fault_reason, reason);
+       else
+               printk(KERN_ERR
+                      "DMAR:[%s] Request device [%02x:%02x.%d] "
+                      "fault addr %llx \n"
+                      "DMAR:[fault reason %02d] %s\n",
+                      (type ? "DMA Read" : "DMA Write"),
+                      (source_id >> 8), PCI_SLOT(source_id & 0xFF),
+                      PCI_FUNC(source_id & 0xFF), addr, fault_reason, reason);
        return 0;
 }
 
 
        spin_lock_irqsave(&iommu->register_lock, flag);
        fault_status = readl(iommu->reg + DMAR_FSTS_REG);
+       if (fault_status)
+               printk(KERN_ERR "DRHD: handling fault status reg %x\n",
+                      fault_status);
 
        /* TBD: ignore advanced fault log currently */
        if (!(fault_status & DMA_FSTS_PPF))
-               goto clear_overflow;
+               goto clear_rest;
 
        fault_index = dma_fsts_fault_record_index(fault_status);
        reg = cap_fault_reg_offset(iommu->cap);
                        fault_index = 0;
                spin_lock_irqsave(&iommu->register_lock, flag);
        }
-clear_overflow:
-       /* clear primary fault overflow */
+clear_rest:
+       /* clear all the other faults */
        fault_status = readl(iommu->reg + DMAR_FSTS_REG);
-       if (fault_status & DMA_FSTS_PFO)
-               writel(DMA_FSTS_PFO, iommu->reg + DMAR_FSTS_REG);
+       writel(fault_status, iommu->reg + DMAR_FSTS_REG);
 
        spin_unlock_irqrestore(&iommu->register_lock, flag);
        return IRQ_HANDLED;
 {
        int irq, ret;
 
+       /*
+        * Check if the fault interrupt is already initialized.
+        */
+       if (iommu->irq)
+               return 0;
+
        irq = create_irq();
        if (!irq) {
                printk(KERN_ERR "IOMMU: no free vectors\n");
                printk(KERN_ERR "IOMMU: can't request irq\n");
        return ret;
 }
+
+int __init enable_drhd_fault_handling(void)
+{
+       struct dmar_drhd_unit *drhd;
+
+       /*
+        * Enable fault control interrupt.
+        */
+       for_each_drhd_unit(drhd) {
+               int ret;
+               struct intel_iommu *iommu = drhd->iommu;
+               ret = dmar_set_interrupt(iommu);
+
+               if (ret) {
+                       printk(KERN_ERR "DRHD %Lx: failed to enable fault, "
+                              " interrupt, ret %d\n",
+                              (unsigned long long)drhd->reg_base_addr, ret);
+                       return -1;
+               }
+       }
+
+       return 0;
+}