[Bug 2074380] Re: [UBUNTU 22.04] s390/cpum_cf: make crypto counters upward compatible

Thanks for the verification, Thomas!
(I'm adjusting the tags accordingly)

** Tags removed: verification-needed-jammy-linux
** Tags added: verification-done-jammy-linux

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https://bugs.launchpad.net/bugs/2074380

Title:
[UBUNTU 22.04] s390/cpum_cf: make crypto counters upward compatible

Status in Ubuntu on IBM z Systems:
Fix Committed
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Jammy:
Fix Committed
Status in linux source package in Noble:
Fix Committed

Bug description:
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.

__________

Description: kernel: s390/cpum_cf: make crypto counters upward
compatible

Symptom: The CPU Measurement facility crypto counter set is not
               listed in the device sysfs tree.

Problem: The CPU Measurement facility crypto counter set is 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 the CPU
               Measurement Facility hardware being incremented on
               new machines. This causes a sanity check to fail,
               but the counters are supported by hardware.

Solution: Remove upper limit in counter second version number
               check.

Reproduction: Run command on a new machine generation:
                # ls -l /sys/devices/cpum_cf/events/ | grep AES
                #
               If the output is empty than this patch is required.
               The output should be:
                # ls /sys/devices/cpum_cf/events/ | grep AES
                AES_BLOCKED_CYCLES
                AES_BLOCKED_FUNCTIONS
                AES_CYCLES
                AES_FUNCTIONS
                #

Upstream-ID of fix: f10933cbd2dfddf6273698a45f76db9bafd8150f

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