On Thu, Nov 14, 2019 at 08:07:35PM +1100, Michael Ellerman wrote: > On Thu, 2019-05-02 at 21:09:07 UTC, Gustavo Walbon wrote: > > From: "Gustavo L. F. Walbon" <gwalbon@xxxxxxxxxxxxx> > > > > The issue was showing "Mitigation" message via sysfs whatever the state of > > "RFI Flush", but it should show "Vulnerable" when it is disabled. > > > > If you have "L1D private" feature enabled and not "RFI Flush" you are > > vulnerable to meltdown attacks. > > > > "RFI Flush" is the key feature to mitigate the meltdown whatever the > > "L1D private" state. > > > > SEC_FTR_L1D_THREAD_PRIV is a feature for Power9 only. > > > > So the message should be as the truth table shows. > > CPU | L1D private | RFI Flush | sysfs | > > ----| ----------- | --------- | ------------------------------------- | > > P9 | False | False | Vulnerable > > P9 | False | True | Mitigation: RFI Flush > > P9 | True | False | Vulnerable: L1D private per thread > > P9 | True | True | Mitigation: RFI Flush, L1D private per > > | | | thread > > P8 | False | False | Vulnerable > > P8 | False | True | Mitigation: RFI Flush > > > > Output before this fix: > > # cat /sys/devices/system/cpu/vulnerabilities/meltdown > > Mitigation: RFI Flush, L1D private per thread > > # echo 0 > /sys/kernel/debug/powerpc/rfi_flush > > # cat /sys/devices/system/cpu/vulnerabilities/meltdown > > Mitigation: L1D private per thread > > > > Output after fix: > > # cat /sys/devices/system/cpu/vulnerabilities/meltdown > > Mitigation: RFI Flush, L1D private per thread > > # echo 0 > /sys/kernel/debug/powerpc/rfi_flush > > # cat /sys/devices/system/cpu/vulnerabilities/meltdown > > Vulnerable: L1D private per thread > > > > Link: https://github.com/linuxppc/issues/issues/243 > > > > Signed-off-by: Gustavo L. F. Walbon <gwalbon@xxxxxxxxxxxxx> > > Signed-off-by: Mauro S. M. Rodrigues <maurosr@xxxxxxxxxxxxxxxxxx> > > Applied to powerpc next, thanks. > > https://git.kernel.org/powerpc/c/4e706af3cd8e1d0503c25332b30cad33c97ed442 > > cheers Fixes: ff348355e9c7 ("powerpc/64s: Enhance the information in cpu_show_meltdown()") Thanks Michal
