Cédric Le Goater's on March 19, 2020 2:45 am: > On 3/18/20 5:41 AM, Nicholas Piggin wrote: >> slbia must invalidate TLBs even if it does not remove a valid SLB >> entry, because slbmte can overwrite valid entries without removing >> their TLBs. >> >> As the architecture says, slbia invalidates all lookaside information, >> not conditionally based on if it removed valid entries. >> >> It does not seem possible for POWER8 or earlier Linux kernels to hit >> this bug because it never changes its kernel SLB translations, and it >> should always have valid entries if any accesses are made to usespace >> regions. However other operating systems which may modify SLB entry 0 >> or do more fancy things with segments might be affected. > > Did you hit the bug on the other OS ?
No, hit it when fixing POWER9 hash. > >> When POWER9 slbia support is added in the next patch, this becomes a >> real problem because some new slbia variants don't invalidate all >> non-zero entries. >> >> Signed-off-by: Nicholas Piggin <npig...@gmail.com> > > Looks correct. > > Reviewed-by: Cédric Le Goater <c...@kaod.org> Thanks, Nick
