diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c index 18a9f05df4079..b3bcd6dec93e7 100644 --- a/drivers/iommu/intel/svm.c +++ b/drivers/iommu/intel/svm.c @@ -1079,8 +1079,17 @@ static irqreturn_t prq_event_thread(int irq, void *d) * Clear the page request overflow bit and wake up all threads that * are waiting for the completion of this handling. */ - if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) - writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG); + if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) { + pr_info_ratelimited("IOMMU: %s: PRQ overflow detected\n", + iommu->name); + head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK; + tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & PRQ_RING_MASK; + if (head == tail) { + writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG); + pr_info_ratelimited("IOMMU: %s: PRQ overflow cleared", + iommu->name); + } + } if (!completion_done(&iommu->prq_complete)) complete(&iommu->prq_complete);