Re: [PATCH v2 0/3] UIO_MEM_DMA_COHERENT for cnic/bnx2/bnx2x

[John Meneghini <jmeneghi@redhat.com>]

Nilesh,

Please explain what has been done to test these patches on bnx2i. Was testing done with iommu enabled/disabled?  Was testing 
done on any/all platforms, or was only x86_64 tested?

Thanks,

/John

On 1/3/24 04:11, Nilesh Javali wrote:
> 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.
> 
> v2:
> - expose only the dma_addr within uio and cnic.
> - Cleanup newly added unions comprising virtual_addr
>    and struct device
> 
> Chris Leech (3):
>    uio: introduce UIO_MEM_DMA_COHERENT type
>    cnic,bnx2,bnx2x: use UIO_MEM_DMA_COHERENT
>    cnic,bnx2,bnx2x: page align uio mmap allocations
> 
>   drivers/net/ethernet/broadcom/bnx2.c          |  2 +
>   .../net/ethernet/broadcom/bnx2x/bnx2x_main.c  | 10 +++--
>   drivers/net/ethernet/broadcom/cnic.c          | 26 ++++++++-----
>   drivers/net/ethernet/broadcom/cnic.h          |  1 +
>   drivers/net/ethernet/broadcom/cnic_if.h       |  1 +
>   drivers/uio/uio.c                             | 38 +++++++++++++++++++
>   include/linux/uio_driver.h                    |  2 +
>   7 files changed, 67 insertions(+), 13 deletions(-)
>