mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-11-01 00:48:50 +00:00
ee0415681e
Resctrl test suite before running any unit test (like cmt, cat, mbm and mba) should first check if the feature is enabled (by kernel and not just supported by H/W) on the platform or not. validate_resctrl_feature_request() is supposed to do that. This function intends to grep for relevant flags in /proc/cpuinfo but there are several issues here 1. validate_resctrl_feature_request() calls fgrep() to get flags from /proc/cpuinfo. But, fgrep() can only return a string with maximum of 255 characters and hence the complete cpu flags are never returned. 2. The substring search logic is also busted. If strstr() finds requested resctrl feature in the cpu flags, it returns pointer to the first occurrence. But, the logic negates the return value of strstr() and hence validate_resctrl_feature_request() returns false if the feature is present in the cpu flags and returns true if the feature is not present. 3. validate_resctrl_feature_request() checks if a resctrl feature is reported in /proc/cpuinfo flags or not. Having a cpu flag means that the H/W supports the feature, but it doesn't mean that the kernel enabled it. A user could selectively enable only a subset of resctrl features using kernel command line arguments. Hence, /proc/cpuinfo isn't a reliable source to check if a feature is enabled or not. The 3rd issue being the major one and fixing it requires changing the way validate_resctrl_feature_request() works. Since, /proc/cpuinfo isn't the right place to check if a resctrl feature is enabled or not, a more appropriate place is /sys/fs/resctrl/info directory. Change validate_resctrl_feature_request() such that, 1. For cat, check if /sys/fs/resctrl/info/L3 directory is present or not 2. For mba, check if /sys/fs/resctrl/info/MB directory is present or not 3. For cmt, check if /sys/fs/resctrl/info/L3_MON directory is present and check if /sys/fs/resctrl/info/L3_MON/mon_features has llc_occupancy 4. For mbm, check if /sys/fs/resctrl/info/L3_MON directory is present and check if /sys/fs/resctrl/info/L3_MON/mon_features has mbm_<total/local>_bytes Please note that only L3_CAT, L3_CMT, MBA and MBM are supported. CDP and L2 variants can be added later. Reported-by: Reinette Chatre <reinette.chatre@intel.com> Tested-by: Babu Moger <babu.moger@amd.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org> |
||
|---|---|---|
| .. | ||
| fault-injection | ||
| ktest | ||
| kunit | ||
| nvdimm | ||
| radix-tree | ||
| scatterlist | ||
| selftests | ||
| vsock | ||