Commit 4aa095ea authored Jun 11, 2019 by Florian Fainelli Committed by Konrad Rzeszutek Wilk Jun 11, 2019

swiotlb: Return consistent SWIOTLB segments/nr_tbl

With a specifically contrived memory layout where there is no physical
memory available to the kernel below the 4GB boundary, we will fail to
perform the initial swiotlb_init() call and set no_iotlb_memory to true.

There are drivers out there that call into swiotlb_nr_tbl() to determine
whether they can use the SWIOTLB. With the right DMA_BIT_MASK() value
for these drivers (say 64-bit), they won't ever need to hit
swiotlb_tbl_map_single() so this can go unoticed and we would be
possibly lying about those drivers.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

parent 0bfaffbf

kernel/dma/swiotlb.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -128,15 +128,17 @@ setup_io_tlb_npages(char *str)
		}
		early_param("swiotlb", setup_io_tlb_npages);

		static bool no_iotlb_memory;

		unsigned long swiotlb_nr_tbl(void)
		{
		return io_tlb_nslabs;
		return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs;
		}
		EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);

		unsigned int swiotlb_max_segment(void)
		{
		return max_segment;
		return unlikely(no_iotlb_memory) ? 0 : max_segment;
		}
		EXPORT_SYMBOL_GPL(swiotlb_max_segment);

		@@ -159,8 +161,6 @@ unsigned long swiotlb_size_or_default(void)
		return size ? size : (IO_TLB_DEFAULT_SIZE);
		}

		static bool no_iotlb_memory;

		void swiotlb_print_info(void)
		{
		unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;