** Changed in: linux (Ubuntu Noble)
Status: In Progress => Fix Committed
** Changed in: linux (Ubuntu Jammy)
Status: In Progress => Fix Committed
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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:
In Progress
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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