+static int qi_check_fault(struct intel_iommu *iommu, int index)
+{
+ u32 fault;
+ int head;
+ struct q_inval *qi = iommu->qi;
+ int wait_index = (index + 1) % QI_LENGTH;
+
+ fault = readl(iommu->reg + DMAR_FSTS_REG);
+
+ /*
+ * If IQE happens, the head points to the descriptor associated
+ * with the error. No new descriptors are fetched until the IQE
+ * is cleared.
+ */
+ if (fault & DMA_FSTS_IQE) {
+ head = readl(iommu->reg + DMAR_IQH_REG);
+ if ((head >> 4) == index) {
+ memcpy(&qi->desc[index], &qi->desc[wait_index],
+ sizeof(struct qi_desc));
+ __iommu_flush_cache(iommu, &qi->desc[index],
+ sizeof(struct qi_desc));
+ writel(DMA_FSTS_IQE, iommu->reg + DMAR_FSTS_REG);
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+