From: Stefano Stabellini stefano.stabellini@xilinx.com
commit e9696d259d0fb5d239e8c28ca41089838ea76d13 upstream.
kernel/dma/swiotlb.c:swiotlb_init gets called first and tries to allocate a buffer for the swiotlb. It does so by calling
memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
If the allocation must fail, no_iotlb_memory is set.
Later during initialization swiotlb-xen comes in (drivers/xen/swiotlb-xen.c:xen_swiotlb_init) and given that io_tlb_start is != 0, it thinks the memory is ready to use when actually it is not.
When the swiotlb is actually needed, swiotlb_tbl_map_single gets called and since no_iotlb_memory is set the kernel panics.
Instead, if swiotlb-xen.c:xen_swiotlb_init knew the swiotlb hadn't been initialized, it would do the initialization itself, which might still succeed.
Fix the panic by setting io_tlb_start to 0 on swiotlb initialization failure, and also by setting no_iotlb_memory to false on swiotlb initialization success.
Fixes: ac2cbab21f31 ("x86: Don't panic if can not alloc buffer for swiotlb")
Reported-by: Elliott Mitchell ehem+xen@m5p.com Tested-by: Elliott Mitchell ehem+xen@m5p.com Signed-off-by: Stefano Stabellini stefano.stabellini@xilinx.com Reviewed-by: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/dma/swiotlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -231,6 +231,7 @@ int __init swiotlb_init_with_tbl(char *t io_tlb_orig_addr[i] = INVALID_PHYS_ADDR; } io_tlb_index = 0; + no_iotlb_memory = false;
if (verbose) swiotlb_print_info(); @@ -262,9 +263,11 @@ swiotlb_init(int verbose) if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose)) return;
- if (io_tlb_start) + if (io_tlb_start) { memblock_free_early(io_tlb_start, PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT)); + io_tlb_start = 0; + } pr_warn("Cannot allocate buffer"); no_iotlb_memory = true; } @@ -362,6 +365,7 @@ swiotlb_late_init_with_tbl(char *tlb, un io_tlb_orig_addr[i] = INVALID_PHYS_ADDR; } io_tlb_index = 0; + no_iotlb_memory = false;
swiotlb_print_info();