xen/swiotlb: don't initialize swiotlb twice on arm64 (4e7372e0) · Commits · 戴 / test

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:

Stefano Stabellini <stefanos@xilinx.com> Reviewed-by:

Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by:

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

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 @@ retry:
		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 @@ retry:
		} 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);

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