Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 681cc5cd authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Linus Torvalds
Browse files

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: default avatarFUJITA 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 59fc67de

lib/swiotlb.c

+35 −6
Original line number Diff line number Diff line
@@ -282,6 +282,15 @@ address_needs_mapping(struct device *hwdev, dma_addr_t addr) 
	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 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir) 
	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 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir) 
	 */

	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)

			index = 0;



		while (is_span_boundary(index, nslots, offset_slots,

					max_slots)) {

			index += stride;

			if (index >= io_tlb_nslabs)

			wrap = index = 0;

				index = 0;

		}

		wrap = index;



		do {

			/*
@@ -341,9 +367,12 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir) 


				goto found;

			}

			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);