Re: [PATCH for-5.2] s390x/pci: fix endianness issues

[Thomas Huth]

On 17/11/2020 18.13, Cornelia Huck wrote:
> zPCI control blocks are big endian, we need to take care that we
> do proper accesses in order not to break tcg guests on little endian
> hosts.
> 
> Fixes: 28dc86a07299 ("s390x/pci: use a PCI Group structure")
> Fixes: 9670ee752727 ("s390x/pci: use a PCI Function structure")
> Fixes: 1e7552ff5c34 ("s390x/pci: get zPCI function info from host")

This fixes the problem with my old Fedora 28 under TCG, too, but... do we
really want to store this information in big endian on the QEMU side (e.g.
in the QTAILQ lists)? ... that smells like trouble again in the future...

I think it would be better if we rather replace all those memcpy() functions
in the patches that you cited in the "Fixes:" lines above with code that
changes the endianess when we copy the date from QEMU space to guest space
and vice versa. What do you think?

 Thomas