Re: [PATCH v3 5/5] vfio-user: Fix config space access byte order

[Stefan Hajnoczi]

On Thu, Sep 07, 2023 at 06:04:10AM -0700, Mattias Nissler wrote:
> PCI config space is little-endian, so on a big-endian host we need to
> perform byte swaps for values as they are passed to and received from
> the generic PCI config space access machinery.
> 
> Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
> ---
>  hw/remote/vfio-user-obj.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

After some discussion about PCI Configuration Space endianness on IRC
with aw, mcayland, and f4bug I am now happy with this patch:

1. Configuration space can only be accessed in 1-, 2-, or 4-byte
   accesses.
2. If it's a 2- or 4-byte access then your patch adds the missing
   little-endian conversion.
3. If it's a 1-byte access then there is (effectively) no byteswap in
   the code path and the pci_dev->config[] array is already
   little-endian.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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