lkml.org 
[lkml]   [2019]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] Fix wrong message when RFI Flush is disable
Date
On Thu, 2019-05-02 at 21:09:07 UTC, Gustavo Walbon wrote:
> From: "Gustavo L. F. Walbon" <gwalbon@linux.ibm.com>
>
> 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@linux.ibm.com>
> Signed-off-by: Mauro S. M. Rodrigues <maurosr@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/4e706af3cd8e1d0503c25332b30cad33c97ed442

cheers

\
 
 \ /
  Last update: 2019-11-14 10:08    [W:0.134 / U:0.408 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site