APPLIED: [SRU][N][J][PATCH 0/1] s390/cpum_cf: make crypto counters upward compatible (LP: 2074380)

[Roxana Nicolescu]

On 01/08/2024 12:53, frank.heimes at canonical.com wrote:
> BugLink: https://bugs.launchpad.net/bugs/2074380
>
> SRU Justification:
>
> [ Impact ]
>
>   * The CPU Measurement Facility (CPU MF) crypto counter set
>     is not listed in the device sysfs tree - it's not exported
>     in the sysfs directory /sys/devices/cpum_cf/events.
>
>   * The attribute files for each CPU-MF counter defined
>     in the crypto counter set is missing.
>
>   * This is caused by the counter second version number of CPU MF
>     hardware being incremented on new machines.
>
>   * This causes a sanity check to fail,
>     but the counters are supported by hardware.
>
>   * The solution is to remove the upper limit in counter second
>     version number check.
>
> [ Fix ]
>
>   * f10933cbd2df f10933cbd2dfddf6273698a45f76db9bafd8150f
>     "s390/cpum_cf: make crypto counters upward compatible across machine types"
>
>   * The fix was upstream accepted with kernel v6.10(-rc1).
>
>   * Upstream commit applies cleanly on noble master-next,
>     but needed to be backported to jammy master-next due to different code
>     and context in kernel 5.15.
>
> [ Test Plan ]
>
>   * Run the following commands on a new machine generation:
>     (hence only doable by IBM)
>     # ls -l /sys/devices/cpum_cf/events/ | grep AES
>
>   * If the output is empty than this patch is required.
>
>   * With a patched kernel the output should be like:
>     # ls /sys/devices/cpum_cf/events/ | grep AES
>     AES_BLOCKED_CYCLES
>     AES_BLOCKED_FUNCTIONS
>     AES_CYCLES
>     AES_FUNCTIONS
>
> [ Where problems could occur ]
>
>   * This affects s390x only - CPU MF is s390-specific,
>     and only s390 specific code is modified.
>
>   * And it furthermore is limited to the crypto counter set
>     of CPU MF.
>
>   * So any impact is likely limited to hardware crypto counters
>     on s390x only.
>
>   * In s390/kernel/perf_cpum_cf.c the else if case got changed from
>     explicitly checking for 6 or 7 to >= 6 which seems to require
>     attention for future 8 and more cases.
>
>   * In s390/kernel/perf_cpum_cf_events.c the switch (ci.csvn) statement
>     was changed to an if / else if with similar logic.
>     Again attentioin for any potential future cases >= 8.
>
>   * It does not look like currently used cases (1..5 and 6..7)
>     are affected by the modification, just >7.
>
>   * Test build of patched jammy and noble s390x kernels were build
>     and are avaiable here:
>     https://launchpad.net/~fheimes/+archive/ubuntu/lp2074380
>
> [ Other Info ]
>
>   * Since the code/fix was upstream accepted with kernel v6.10(-rc1)
>     it does not affect the current development release oracular.
>
>   * This SRU can also be seen under the umbrella of new
>      hardware enablement.
>
>   * Since it requires special hw, the verification needs to be
>     done by IBM.
>
> Thomas Richter (1):
>    s390/cpum_cf: make crypto counters upward compatible across machine
>      types
>
>   arch/s390/kernel/perf_cpum_cf.c        |  2 +-
>   arch/s390/kernel/perf_cpum_cf_events.c | 11 +++--------
>   2 files changed, 4 insertions(+), 9 deletions(-)
>
Applied to noble:linux, jammy:linux master-next branches. Thanks!