@@ -1575,10 +1575,17 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
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 */
@@ -1600,24 +1607,28 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
if (!(data & DMA_FRCD_F))
break;
- fault_reason = dma_frcd_fault_reason(data);
- type = dma_frcd_type(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);
+ 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))
This is a note to let you know that I have just added a patch titled iommu/vt-d: Ratelimit fault handler to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 9c8203c76828d2e8c7c69edc175bb7278e983bae Mon Sep 17 00:00:00 2001 From: Alex Williamson <alex.williamson@redhat.com> Date: Thu, 17 Mar 2016 14:12:25 -0600 Subject: iommu/vt-d: Ratelimit fault handler 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 <alex.williamson@redhat.com> Fixes: 0ac2491f57af ('x86, dmar: move page fault handling code to dmar.c') Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/iommu/dmar.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) -- 2.7.4