On Tue, 27 Oct 2020, Konrad Rzeszutek Wilk wrote: > On Mon, Oct 26, 2020 at 05:02:14PM -0700, Stefano Stabellini wrote: > > From: Stefano Stabellini <stefano.stabell...@xilinx.com> > > > > 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. > > Should this have a Fixes: flag?
That would be Fixes: ac2cbab21f31 ("x86: Don't panic if can not alloc buffer for swiotlb") > > Signed-off-by: Stefano Stabellini <stefano.stabell...@xilinx.com> > > > > > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > > index c19379fabd20..9924214df60a 100644 > > --- a/kernel/dma/swiotlb.c > > +++ b/kernel/dma/swiotlb.c > > @@ -231,6 +231,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned > > long nslabs, int verbose) > > 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, unsigned long > > nslabs) > > io_tlb_orig_addr[i] = INVALID_PHYS_ADDR; > > } > > io_tlb_index = 0; > > + no_iotlb_memory = false; > > > > swiotlb_print_info(); > > > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu