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Subject[PATCH 5.0 126/238] swiotlb: Add is_swiotlb_active() function
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joerg Roedel <jroedel@suse.de>

commit 492366f7b4237257ef50ca9c431a6a0d50225aca upstream.

This function will be used from dma_direct code to determine
the maximum segment size of a dma mapping.

Cc: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/swiotlb.h | 6 ++++++
kernel/dma/swiotlb.c | 9 +++++++++
2 files changed, 15 insertions(+)

--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -77,6 +77,7 @@ bool swiotlb_map(struct device *dev, phy
void __init swiotlb_exit(void);
unsigned int swiotlb_max_segment(void);
size_t swiotlb_max_mapping_size(struct device *dev);
+bool is_swiotlb_active(void);
#else
#define swiotlb_force SWIOTLB_NO_FORCE
static inline bool is_swiotlb_buffer(phys_addr_t paddr)
@@ -100,6 +101,11 @@ static inline size_t swiotlb_max_mapping
{
return SIZE_MAX;
}
+
+static inline bool is_swiotlb_active(void)
+{
+ return false;
+}
#endif /* CONFIG_SWIOTLB */

extern void swiotlb_print_info(void);
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -667,3 +667,12 @@ size_t swiotlb_max_mapping_size(struct d
{
return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
}
+
+bool is_swiotlb_active(void)
+{
+ /*
+ * When SWIOTLB is initialized, even if io_tlb_start points to physical
+ * address zero, io_tlb_end surely doesn't.
+ */
+ return io_tlb_end != 0;
+}

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