[PATCH 3.16 006/305] iommu/vt-d: Ratelimit fault handler
From: Ben Hutchings <hidden>
Date: 2016-08-14 11:20:36
Also in:
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3.16.37-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Alex Williamson <redacted>
commit c43fce4eebae257ca413733690e2076757282093 upstream.
Fault rates can easily overwhelm the console and make the system
unresponsive. Ratelimit to allow an opportunity for maintenance.
Signed-off-by: Alex Williamson <redacted>
Fixes: 0ac2491f57af ('x86, dmar: move page fault handling code to dmar.c')
Signed-off-by: Joerg Roedel <redacted>
Signed-off-by: Ben Hutchings <redacted>
---
drivers/iommu/dmar.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c@@ -1482,10 +1482,17 @@ irqreturn_t dmar_fault(int irq, void *de int reg, fault_index; u32 fault_status; unsigned long flag; + bool ratelimited; + static DEFINE_RATELIMIT_STATE(rs, + DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + + /* Disable printing, simply clear the fault when ratelimited */ + ratelimited = !__ratelimit(&rs); raw_spin_lock_irqsave(&iommu->register_lock, flag); fault_status = readl(iommu->reg + DMAR_FSTS_REG); - if (fault_status) + if (fault_status && !ratelimited) pr_err("DRHD: handling fault status reg %x\n", fault_status); /* TBD: ignore advanced fault log currently */
@@ -1507,24 +1514,28 @@ irqreturn_t dmar_fault(int irq, void *de if (!(data & DMA_FRCD_F)) break; - fault_reason = dma_frcd_fault_reason(data); - type = dma_frcd_type(data); - - data = readl(iommu->reg + reg + - fault_index * PRIMARY_FAULT_REG_LEN + 8); - source_id = dma_frcd_source_id(data); + if (!ratelimited) { + fault_reason = dma_frcd_fault_reason(data); + type = dma_frcd_type(data); + + data = readl(iommu->reg + reg + + fault_index * PRIMARY_FAULT_REG_LEN + 8); + source_id = dma_frcd_source_id(data); + + guest_addr = dmar_readq(iommu->reg + reg + + fault_index * PRIMARY_FAULT_REG_LEN); + guest_addr = dma_frcd_page_addr(guest_addr); + } - guest_addr = dmar_readq(iommu->reg + reg + - fault_index * PRIMARY_FAULT_REG_LEN); - guest_addr = dma_frcd_page_addr(guest_addr); /* clear the fault */ writel(DMA_FRCD_F, iommu->reg + reg + fault_index * PRIMARY_FAULT_REG_LEN + 12); raw_spin_unlock_irqrestore(&iommu->register_lock, flag); - dmar_fault_do_one(iommu, type, fault_reason, - source_id, guest_addr); + if (!ratelimited) + dmar_fault_do_one(iommu, type, fault_reason, + source_id, guest_addr); fault_index++; if (fault_index >= cap_num_fault_regs(iommu->cap))