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Commit 4e7372e0 authored by Stefano Stabellini's avatar Stefano Stabellini Committed by Konrad Rzeszutek Wilk
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xen/swiotlb: don't initialize swiotlb twice on arm64 



On arm64 swiotlb is often (not always) already initialized by mem_init.
We don't want to initialize it twice, which would trigger a second
memory allocation. Moreover, the second memory pool is typically made of
high pages and ends up replacing the original memory pool of low pages.
As a side effect of this change, it is possible to have low pages in
swiotlb-xen on arm64.

Signed-off-by: default avatarStefano Stabellini <stefanos@xilinx.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 063b8271

drivers/xen/swiotlb-xen.c

+11 −1
Original line number Diff line number Diff line
@@ -211,6 +211,15 @@ int __ref xen_swiotlb_init(int verbose, bool early) 
retry:

	bytes = xen_set_nslabs(xen_io_tlb_nslabs);

	order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);



	/*

	 * IO TLB memory already allocated. Just use it.

	 */

	if (io_tlb_start != 0) {

		xen_io_tlb_start = phys_to_virt(io_tlb_start);

		goto end;

	}



	/*

	 * Get IO TLB memory from any location.

	 */
@@ -237,7 +246,6 @@ int __ref xen_swiotlb_init(int verbose, bool early) 
		m_ret = XEN_SWIOTLB_ENOMEM;

		goto error;

	}

	xen_io_tlb_end = xen_io_tlb_start + bytes;

	/*

	 * And replace that memory with pages under 4GB.

	 */
@@ -264,6 +272,8 @@ int __ref xen_swiotlb_init(int verbose, bool early) 
	} else

		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);



end:

	xen_io_tlb_end = xen_io_tlb_start + bytes;

	if (!rc)

		swiotlb_set_max_segment(PAGE_SIZE);