[PATCH 1/3] iommu/vt-d: Add rate limited information when PRQ overflows

[Lu Baolu]

So that the uses could get chances to know what happened.

Suggested-by: Ashok Raj <ashok....@intel.com>
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/iommu/intel/svm.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 033b25886e57..f49fe715477b 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -895,6 +895,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
        struct intel_iommu *iommu = d;
        struct intel_svm *svm = NULL;
        int head, tail, handled = 0;
+       struct page_req_dsc *req;
 
        /* Clear PPR bit before reading head/tail registers, to
         * ensure that we get a new interrupt if needed. */
@@ -904,7 +905,6 @@ static irqreturn_t prq_event_thread(int irq, void *d)
        head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK;
        while (head != tail) {
                struct vm_area_struct *vma;
-               struct page_req_dsc *req;
                struct qi_desc resp;
                int result;
                vm_fault_t ret;
@@ -1042,8 +1042,14 @@ 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)
+       if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) {
+               head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK;
+               req = &iommu->prq[head / sizeof(*req)];
+               pr_warn_ratelimited("IOMMU: %s: Page request overflow: HEAD: 
%08llx %08llx",
+                                   iommu->name, ((unsigned long long *)req)[0],
+                                   ((unsigned long long *)req)[1]);
                writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG);
+       }
 
        if (!completion_done(&iommu->prq_complete))
                complete(&iommu->prq_complete);
-- 
2.25.1