[PATCH 7/7] swiotlb: don't override the command line in swiotlb_adjust_size

[Christoph Hellwig]

When the user specified an explicit swiotlb size on the command line,
the achitecture code should not override it.

Fixes: 2cbc2776efe4 ("swiotlb: remove swiotlb_nr_tbl")
Reported-by: Tom Lendacky <thomas.lendacky at amd.com>
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 kernel/dma/swiotlb.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 87d06ddf4753f3..aef02a3825b494 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -106,7 +106,9 @@ void swiotlb_set_max_segment(unsigned int val)
 
 unsigned long swiotlb_size_or_default(void)
 {
-	return swiotlb_default_size;
+	if (swiotlb_default_size)
+		return swiotlb_default_size;
+	return IO_TLB_DEFAULT_SIZE;
 }
 
 void __init swiotlb_adjust_size(unsigned long size)
@@ -116,6 +118,8 @@ void __init swiotlb_adjust_size(unsigned long size)
 	 * architectures such as those supporting memory encryption to
 	 * adjust/expand SWIOTLB size for their use.
 	 */
+	if (swiotlb_default_size)
+		return;
 	swiotlb_default_size = ALIGN(size, IO_TLB_SEGSIZE << IO_TLB_SHIFT);
 	pr_info("SWIOTLB bounce buffer size adjusted to %luMB",
 		swiotlb_default_size >> 20);
-- 
2.30.1