[PATCHv4 2/2] iommu/vt-d: Limit number of faults to clear in irq handler

Dmitry Safonov
2018-03-31T00:33:20Z

Theoretically, on some machines faults might be generated faster than
they're cleared by CPU. Let's limit the cleaning-loop by number of hw
fault registers.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
drivers/iommu/dmar.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 6c4ea32ee6a9..cf1105111209 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1615,7 +1615,7 @@ static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
irqreturn_t dmar_fault(int irq, void *dev_id)
{
struct intel_iommu *iommu = dev_id;
- int reg, fault_index;
+ int reg, fault_index, i;
u32 fault_status;
unsigned long flag;
static DEFINE_RATELIMIT_STATE(rs,
@@ -1633,7 +1633,7 @@ irqreturn_t dmar_fault(int irq, void *dev_id)

fault_index = dma_fsts_fault_record_index(fault_status);
reg = cap_fault_reg_offset(iommu->cap);
- while (1) {
+ for (i = 0; i < cap_num_fault_regs(iommu->cap); i++) {
/* Disable printing, simply clear the fault when ratelimited */
bool ratelimited = !__ratelimit(&rs);
u8 fault_reason;
--
2.13.6