[PATCH 4/7] iommu/amd: Add locking to per-domain flush-queue

[Joerg Roedel]

From: Joerg Roedel <jroe...@suse.de>

With locking we can safely access the flush-queues of other
cpus.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 drivers/iommu/amd_iommu.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 6a5c858..9aa2735 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -144,6 +144,7 @@ struct flush_queue_entry {
 struct flush_queue {
        struct flush_queue_entry *entries;
        unsigned head, tail;
+       spinlock_t lock;
 };
 
 /*
@@ -1773,6 +1774,8 @@ static int dma_ops_domain_alloc_flush_queue(struct 
dma_ops_domain *dom)
                        dma_ops_domain_free_flush_queue(dom);
                        return -ENOMEM;
                }
+
+               spin_lock_init(&queue->lock);
        }
 
        return 0;
@@ -1780,6 +1783,8 @@ static int dma_ops_domain_alloc_flush_queue(struct 
dma_ops_domain *dom)
 
 static inline bool queue_ring_full(struct flush_queue *queue)
 {
+       assert_spin_locked(&queue->lock);
+
        return (((queue->tail + 1) % FLUSH_QUEUE_SIZE) == queue->head);
 }
 
@@ -1791,6 +1796,8 @@ static void queue_release(struct dma_ops_domain *dom,
 {
        unsigned i;
 
+       assert_spin_locked(&queue->lock);
+
        queue_ring_for_each(i, queue)
                free_iova_fast(&dom->iovad,
                               queue->entries[i].iova_pfn,
@@ -1803,6 +1810,7 @@ static inline unsigned queue_ring_add(struct flush_queue 
*queue)
 {
        unsigned idx = queue->tail;
 
+       assert_spin_locked(&queue->lock);
        queue->tail = (idx + 1) % FLUSH_QUEUE_SIZE;
 
        return idx;
@@ -1812,12 +1820,14 @@ static void queue_add(struct dma_ops_domain *dom,
                      unsigned long address, unsigned long pages)
 {
        struct flush_queue *queue;
+       unsigned long flags;
        int idx;
 
        pages     = __roundup_pow_of_two(pages);
        address >>= PAGE_SHIFT;
 
        queue = get_cpu_ptr(dom->flush_queue);
+       spin_lock_irqsave(&queue->lock, flags);
 
        if (queue_ring_full(queue)) {
                domain_flush_tlb(&dom->domain);
@@ -1830,6 +1840,7 @@ static void queue_add(struct dma_ops_domain *dom,
        queue->entries[idx].iova_pfn = address;
        queue->entries[idx].pages    = pages;
 
+       spin_unlock_irqrestore(&queue->lock, flags);
        put_cpu_ptr(dom->flush_queue);
 }
 
-- 
2.7.4