linux-stable/kernel/dma
Stefano Stabellini e9696d259d swiotlb: fix "x86: Don't panic if can not alloc buffer for swiotlb"
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: ac2cbab21f ("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>
2020-11-02 10:10:37 -05:00
..
coherent.c dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00
contiguous.c dma-mapping updates for 5.10 2020-10-15 14:43:29 -07:00
debug.c dma-mapping: move dma-debug.h to kernel/dma/ 2020-10-06 07:07:05 +02:00
debug.h dma-mapping: move dma-debug.h to kernel/dma/ 2020-10-06 07:07:05 +02:00
direct.c kernel/: fix repeated words in comments 2020-10-16 11:11:19 -07:00
direct.h dma-mapping: move large parts of <linux/dma-direct.h> to kernel/dma 2020-10-06 07:07:06 +02:00
dummy.c dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00
Kconfig dma-mapping: merge <linux/dma-contiguous.h> into <linux/dma-map-ops.h> 2020-10-06 07:07:04 +02:00
Makefile dma-mapping: move dma_common_{mmap,get_sgtable} out of mapping.c 2020-09-11 09:14:56 +02:00
mapping.c dma-mapping: move large parts of <linux/dma-direct.h> to kernel/dma 2020-10-06 07:07:06 +02:00
ops_helpers.c dma-mapping: merge <linux/dma-noncoherent.h> into <linux/dma-map-ops.h> 2020-10-06 07:07:06 +02:00
pool.c dma-mapping: merge <linux/dma-noncoherent.h> into <linux/dma-map-ops.h> 2020-10-06 07:07:06 +02:00
remap.c dma-mapping: move more functions to dma-map-ops.h 2020-10-20 10:41:07 +02:00
swiotlb.c swiotlb: fix "x86: Don't panic if can not alloc buffer for swiotlb" 2020-11-02 10:10:37 -05:00
virt.c dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00