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: Stefano Stabellini <stefanos@xilinx.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 64cb94d..342762b 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -211,6 +211,15 @@
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 @@
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 @@
} 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);
