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Subject[PATCH 14/20] iommu/amd: Implement timeout to flush unmap queues
Date
From: Joerg Roedel <jroedel@suse.de>

In case the queue doesn't fill up, we flush the TLB at least
10ms after the unmap happened to make sure that the TLB is
cleaned up.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/amd_iommu.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index a3e09cd..1bb003e 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -104,6 +104,9 @@ struct flush_queue {

DEFINE_PER_CPU(struct flush_queue, flush_queue);

+static atomic_t queue_timer_on;
+static struct timer_list queue_timer;
+
/*
* Domain for untranslated devices - only allocated
* if iommu=pt passed on kernel cmd line.
@@ -2159,6 +2162,24 @@ static void __queue_flush(struct flush_queue *queue)
queue->next = 0;
}

+void queue_flush_timeout(unsigned long unsused)
+{
+ int cpu;
+
+ atomic_set(&queue_timer_on, 0);
+
+ for_each_possible_cpu(cpu) {
+ struct flush_queue *queue;
+ unsigned long flags;
+
+ queue = per_cpu_ptr(&flush_queue, cpu);
+ spin_lock_irqsave(&queue->lock, flags);
+ if (queue->next > 0)
+ __queue_flush(queue);
+ spin_unlock_irqrestore(&queue->lock, flags);
+ }
+}
+
static void queue_add(struct dma_ops_domain *dma_dom,
unsigned long address, unsigned long pages)
{
@@ -2184,6 +2205,10 @@ static void queue_add(struct dma_ops_domain *dma_dom,
entry->dma_dom = dma_dom;

spin_unlock_irqrestore(&queue->lock, flags);
+
+ if (atomic_cmpxchg(&queue_timer_on, 0, 1) == 0)
+ mod_timer(&queue_timer, jiffies + msecs_to_jiffies(10));
+
put_cpu_ptr(&flush_queue);
}

@@ -2639,6 +2664,9 @@ out_put_iova:

int __init amd_iommu_init_dma_ops(void)
{
+ setup_timer(&queue_timer, queue_flush_timeout, 0);
+ atomic_set(&queue_timer_on, 0);
+
swiotlb = iommu_pass_through ? 1 : 0;
iommu_detected = 1;

--
1.9.1
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