The BMEC (Bandwidth Monitoring Event Configuration) feature enables per-domain event configuration. With BMEC the MBM events are configured using the mbm_total_bytes_config or mbm_local_bytes_config files in /sys/fs/resctrl/info/L3_MON/ and the per-domain event configuration affects all monitor resource groups. The mbm_event counter assignment mode enables counters to be assigned to RMID (i.e a monitor resource group), event pairs, with potentially unique event configurations associated with every counter. There may be systems that support both BMEC and mbm_event counter assignment mode, but resctrl supporting both concurrently will present a conflicting interface to the user with both per-domain and per RMID, event configurations active at the same time. The mbm_event counter assignment provides most flexibility to user space and aligns with Arm's counter support. On systems that support both, disable BMEC event configuration when mbm_event mode is enabled by hiding the mbm_total_bytes_config or mbm_local_bytes_config files when mbm_event mode is enabled. Ensure mon_features always displays accurate information about monitor features. Suggested-by: Reinette Chatre Signed-off-by: Babu Moger Reviewed-by: Reinette Chatre --- v18: Added Reviewed-by tag. v17: Fixed the extra reference release in resctrl_bmec_files_show(). v16: Added new comment in resctrl_bmec_files_show() about kernfs_find_and_get failure. Added the parameter to resctrl_bmec_files_show() to pass the kernfs_node. v15: Updated the changelog. Moved resctrl_bmec_files_show() inside rdtgroup_mkdir_info_resdir(). Removed the unnecessary kernfs_get() call. v14: Updated the changelog for change in mbm_assign_modes. Added check in rdt_mon_features_show to hide bmec related feature. v13: New patch to hide BMEC related files. --- fs/resctrl/rdtgroup.c | 47 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-) diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index bd4a115ffea1..0c404a159d45 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -1150,7 +1150,8 @@ static int rdt_mon_features_show(struct kernfs_open_file *of, if (mevt->rid != r->rid || !mevt->enabled) continue; seq_printf(seq, "%s\n", mevt->name); - if (mevt->configurable) + if (mevt->configurable && + !resctrl_arch_mbm_cntr_assign_enabled(r)) seq_printf(seq, "%s_config\n", mevt->name); } @@ -1799,6 +1800,44 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of, return ret ?: nbytes; } +/* + * resctrl_bmec_files_show() — Controls the visibility of BMEC-related resctrl + * files. When @show is true, the files are displayed; when false, the files + * are hidden. + * Don't treat kernfs_find_and_get failure as an error, since this function may + * be called regardless of whether BMEC is supported or the event is enabled. + */ +static void resctrl_bmec_files_show(struct rdt_resource *r, struct kernfs_node *l3_mon_kn, + bool show) +{ + struct kernfs_node *kn_config, *mon_kn = NULL; + char name[32]; + + if (!l3_mon_kn) { + sprintf(name, "%s_MON", r->name); + mon_kn = kernfs_find_and_get(kn_info, name); + if (!mon_kn) + return; + l3_mon_kn = mon_kn; + } + + kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_total_bytes_config"); + if (kn_config) { + kernfs_show(kn_config, show); + kernfs_put(kn_config); + } + + kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_local_bytes_config"); + if (kn_config) { + kernfs_show(kn_config, show); + kernfs_put(kn_config); + } + + /* Release the reference only if it was acquired */ + if (mon_kn) + kernfs_put(mon_kn); +} + /* rdtgroup information files for one cache resource. */ static struct rftype res_common_files[] = { { @@ -2267,6 +2306,12 @@ static int rdtgroup_mkdir_info_resdir(void *priv, char *name, ret = resctrl_mkdir_event_configs(r, kn_subdir); if (ret) return ret; + /* + * Hide BMEC related files if mbm_event mode + * is enabled. + */ + if (resctrl_arch_mbm_cntr_assign_enabled(r)) + resctrl_bmec_files_show(r, kn_subdir, false); } } -- 2.34.1