[PATCH 0/3] UIO_MEM_DMA_COHERENT for cnic/bnx2/bnx2x

Chris Leech
2023-09-29T17:01:48Z

During bnx2i iSCSI testing we ran into page refcounting issues in the
uio mmaps exported from cnic to the iscsiuio process, and bisected back
to the removal of the __GFP_COMP flag from dma_alloc_coherent calls.

In order to fix these drivers to be able to mmap dma coherent memory via
a uio device, without resorting to hacks and working with an iommu
enabled, introduce a new uio mmap type backed by dma_mmap_coherent.

While converting the uio interface, I also noticed that not all of these
allocations were PAGE_SIZE aligned. Particularly the bnx2/bnx2x status
block mapping was much smaller than any architecture page size, and I
was concerned that it could be unintentionally exposing kernel memory.

Chris Leech (3):
uio: introduce UIO_DMA_COHERENT type
cnic. bnx2, bnx2x: page align uio mmap allocations
cnic, bnx2, bnx2x: use UIO_MEM_DMA_COHERENT

drivers/net/ethernet/broadcom/bnx2.c | 2 ++
.../net/ethernet/broadcom/bnx2x/bnx2x_main.c | 10 +++---
drivers/net/ethernet/broadcom/cnic.c | 34 ++++++++++++-------
drivers/net/ethernet/broadcom/cnic.h | 1 +
drivers/net/ethernet/broadcom/cnic_if.h | 1 +
drivers/uio/uio.c | 34 +++++++++++++++++++
include/linux/uio_driver.h | 12 +++++--
7 files changed, 75 insertions(+), 19 deletions(-)

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2.41.0