From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
Hyper-V Isolation VM may fail to allocate swiotlb bounce buffer due
to there is no enough contiguous memory from 0 to 4G in some cases.
Current swiotlb code allocates bounce buffer in the low end memory.
This patchset adds a new function swiotlb_set_alloc_from_low_pages()
to control swiotlb bounce buffer from low pages or no limitation.
Devices in Hyper-V Isolation VM may use memory above 4G as DMA memory
and switch swiotlb allocation in order to avoid no enough contiguous
memory in low pages.
Tianyu Lan (2):
Swiotlb: Add swiotlb_alloc_from_low_pages switch
x86/hyperv: Make swiotlb bounce buffer allocation not just from low
pages
arch/x86/kernel/cpu/mshyperv.c | 1 +
include/linux/swiotlb.h | 1 +
kernel/dma/swiotlb.c | 18 ++++++++++++++++--
3 files changed, 18 insertions(+), 2 deletions(-)
--
2.25.1
