From 4e7372e0dc5d7d2078fbdb13505635cd5b11f93d Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Tue, 28 May 2019 15:48:22 -0700 Subject: [PATCH] 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 Reviewed-by: Boris Ostrovsky Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/swiotlb-xen.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 64cb94dfedd4..342762b1aefb 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -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);