iommu sg merging: swiotlb: respect the segment boundary limits
This patch makes swiotlb not allocate a memory area spanning LLD's segment
boundary.
is_span_boundary() judges whether a memory area spans LLD's segment boundary.
If map_single finds such a area, map_single tries to find the next available
memory area.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Greg KH <greg@kroah.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 1a8050a..4bb5a11 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -282,6 +282,15 @@
return (addr & ~mask) != 0;
}
+static inline unsigned int is_span_boundary(unsigned int index,
+ unsigned int nslots,
+ unsigned long offset_slots,
+ unsigned long max_slots)
+{
+ unsigned long offset = (offset_slots + index) & (max_slots - 1);
+ return offset + nslots > max_slots;
+}
+
/*
* Allocates bounce buffer and returns its kernel virtual address.
*/
@@ -292,6 +301,16 @@
char *dma_addr;
unsigned int nslots, stride, index, wrap;
int i;
+ unsigned long start_dma_addr;
+ unsigned long mask;
+ unsigned long offset_slots;
+ unsigned long max_slots;
+
+ mask = dma_get_seg_boundary(hwdev);
+ start_dma_addr = virt_to_bus(io_tlb_start) & mask;
+
+ offset_slots = ALIGN(start_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+ max_slots = ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
/*
* For mappings greater than a page, we limit the stride (and
@@ -311,10 +330,17 @@
*/
spin_lock_irqsave(&io_tlb_lock, flags);
{
- wrap = index = ALIGN(io_tlb_index, stride);
-
+ index = ALIGN(io_tlb_index, stride);
if (index >= io_tlb_nslabs)
- wrap = index = 0;
+ index = 0;
+
+ while (is_span_boundary(index, nslots, offset_slots,
+ max_slots)) {
+ index += stride;
+ if (index >= io_tlb_nslabs)
+ index = 0;
+ }
+ wrap = index;
do {
/*
@@ -341,9 +367,12 @@
goto found;
}
- index += stride;
- if (index >= io_tlb_nslabs)
- index = 0;
+ do {
+ index += stride;
+ if (index >= io_tlb_nslabs)
+ index = 0;
+ } while (is_span_boundary(index, nslots, offset_slots,
+ max_slots));
} while (index != wrap);
spin_unlock_irqrestore(&io_tlb_lock, flags);