Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN is meant,
I suspect this is because the first support for Xen was for PV. This brough some

Typo : "brought"
Perhaps "resulted in" would be better ?

misimplementation of helpers on ARM and make the developper confused the expected behavior.

Typo: "developer".
I'd also suggest "...and confused developers about the...".

[...]

For clarity and avoid new confusion, replace any reference of mfn into gnf in any helpers used by PV drivers.

Typo : "gfn"
I'd suggest "...replace any reference to mfn with gfn..."

[...]

Chris