1 files changed, 44 insertions, 0 deletions

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 1d8b37747bf0..bedc9f945836 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -34,6 +34,9 @@
 #include <linux/scatterlist.h>
 #include <linux/mem_encrypt.h>
 #include <linux/set_memory.h>
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
 
 #include <asm/io.h>
 #include <asm/dma.h>
@@ -73,6 +76,11 @@ phys_addr_t io_tlb_start, io_tlb_end;
 static unsigned long io_tlb_nslabs;
 
 /*
+ * The number of used IO TLB block
+ */
+static unsigned long io_tlb_used;
+
+/*
  * This is a free list describing the number of free entries available from
  * each index
  */
@@ -524,6 +532,7 @@ not_found:
                 dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size);
         return DMA_MAPPING_ERROR;
 found:
+        io_tlb_used += nslots;
         spin_unlock_irqrestore(&io_tlb_lock, flags);
 
         /*
@@ -584,6 +593,8 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
                  */
                 for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
                         io_tlb_list[i] = ++count;
+
+                io_tlb_used -= nslots;
         }
         spin_unlock_irqrestore(&io_tlb_lock, flags);
 }
@@ -662,3 +673,36 @@ swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
         return __phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
 }
+
+#ifdef CONFIG_DEBUG_FS
+
+static int __init swiotlb_create_debugfs(void)
+{
+        static struct dentry *d_swiotlb_usage;
+        struct dentry *ent;
+
+        d_swiotlb_usage = debugfs_create_dir("swiotlb", NULL);
+
+        if (!d_swiotlb_usage)
+                return -ENOMEM;
+
+        ent = debugfs_create_ulong("io_tlb_nslabs", 0400,
+                                   d_swiotlb_usage, &io_tlb_nslabs);
+        if (!ent)
+                goto fail;
+
+        ent = debugfs_create_ulong("io_tlb_used", 0400,
+                                   d_swiotlb_usage, &io_tlb_used);
+        if (!ent)
+                goto fail;
+
+        return 0;
+
+fail:
+        debugfs_remove_recursive(d_swiotlb_usage);
+        return -ENOMEM;
+}
+
+late_initcall(swiotlb_create_debugfs);
+
+#endif