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Keep the default to ABMC when supported. >>      Fixed comments to reflect changed interface "mbm_mode". >> >> v3: New patch to address the review comments from upstream. >> --- >>   Documentation/arch/x86/resctrl.rst     | 10 +++++++ >>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 37 +++++++++++++++++++++++++- >>   2 files changed, 46 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/arch/x86/resctrl.rst >> b/Documentation/arch/x86/resctrl.rst >> index 11b7a5f26b40..4c41c5622627 100644 >> --- a/Documentation/arch/x86/resctrl.rst >> +++ b/Documentation/arch/x86/resctrl.rst >> @@ -291,6 +291,16 @@ with the following files: >>       Without ABMC enabled, monitoring will work in "legacy" mode >>       without assignment option. >> +    * To enable ABMC feature: >> +      :: >> + >> +        # echo  "abmc" > /sys/fs/resctrl/info/L3_MON/mbm_mode >> + >> +    * To enable the legacy monitoring feature: >> +      :: >> + >> +        # echo  "legacy" > /sys/fs/resctrl/info/L3_MON/mbm_mode >> + > > Needs details on what user can expect to happen to counters/data when > switching between modes. Sure. Will add the details. > >>   "num_mbm_cntrs": >>       The number of monitoring counters available for assignment. >> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> index 475a0c7b2a25..531233779f8d 100644 >> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> @@ -910,6 +910,40 @@ static int rdtgroup_num_mbm_cntrs_show(struct >> kernfs_open_file *of, >>       return 0; >>   } >> +static ssize_t rdtgroup_mbm_mode_write(struct kernfs_open_file *of, >> +                       char *buf, size_t nbytes, >> +                       loff_t off) >> +{ >> +    struct rdt_resource *r = of->kn->parent->priv; >> +    int ret = 0; >> + >> +    if (!r->mon.abmc_capable) >> +        return -EINVAL; >> + > > Why should a user not be able to write "legacy" into this > file if "legacy" is the only mode supported? Yes. Will fix it. > >> +    /* Valid input requires a trailing newline */ >> +    if (nbytes == 0 || buf[nbytes - 1] != '\n') >> +        return -EINVAL; >> + >> +    buf[nbytes - 1] = '\0'; >> + >> +    cpus_read_lock(); >> +    mutex_lock(&rdtgroup_mutex); >> + >> +    rdt_last_cmd_clear(); >> + >> +    if (!strcmp(buf, "legacy")) >> +        resctrl_arch_abmc_disable(); >> +    else if (!strcmp(buf, "abmc")) >> +        ret = resctrl_arch_abmc_enable(); >> +    else >> +        ret = -EINVAL; >> + >> +    mutex_unlock(&rdtgroup_mutex); >> +    cpus_read_unlock(); >> + >> +    return ret ?: nbytes; >> +} >> + >>   #ifdef CONFIG_PROC_CPU_RESCTRL >>   /* >> @@ -2103,9 +2137,10 @@ static struct rftype res_common_files[] = { >>       }, >>       { >>           .name        = "mbm_mode", >> -        .mode        = 0444, >> +        .mode        = 0644, >>           .kf_ops        = &rdtgroup_kf_single_ops, >>           .seq_show    = rdtgroup_mbm_mode_show, >> +        .write        = rdtgroup_mbm_mode_write, >>       }, >>       { >>           .name        = "cpus", > > Reinette > -- - Babu Moger