On Tue, 26 May 2020 16:18:08 +1000, Michael Ellerman wrote:

Commit 702f09805222 ("powerpc/64s/exception: Remove lite interrupt
return") changed the interrupt return path to not restore non-volatile
registers by default, and explicitly restore them in paths where it is
required.

But it missed that the facility unavailable exception can sometimes
modify user registers, ie. when it does emulation of move from DSCR.

[...]

Applied to powerpc/fixes.

[1/1] powerpc/64s: Fix restore of NV GPRs after facility unavailable exception
      https://git.kernel.org/powerpc/c/595d153dd1022392083ac93a1550382cbee127e0

cheers