RE: [PATCH v5 09/12] x86/resctrl: Add sysfs interface to write mbm_total_bytes event configuration

["Yu, Fenghua" <fenghua.yu@intel.com>]

Hi, Babu,

> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 27bf6ade0dbf..c1d43d03846a 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1491,6 +1491,144 @@ static int mbm_local_config_show(struct
> kernfs_open_file *of,
>  	return 0;
>  }
> 
> +void mon_event_config_write(void *info) {

Should this function be static?

> +	struct mon_config_info *mon_info = info;
> +	u32 msr_index;
> +
> +	switch (mon_info->evtid) {
> +	case QOS_L3_MBM_TOTAL_EVENT_ID:
> +		msr_index = 0;
> +		break;
> +	case QOS_L3_MBM_LOCAL_EVENT_ID:
> +		msr_index = 1;
> +		break;
> +	default:
> +		/* Not expected to come here */
> +		return;
> +	}
> +
> +	wrmsr(MSR_IA32_EVT_CFG_BASE + msr_index, mon_info->mon_config,
> 0); }
> +
> +int mbm_config_write(struct rdt_resource *r, struct rdt_domain *d,
> +		     u32 evtid, u32 val)
> +{
> +	struct mon_config_info mon_info = {0};
> +	cpumask_var_t cpu_mask;
> +	int ret = 0, cpu;
> +
> +	rdt_last_cmd_clear();
> +
> +	/* mon_config cannot be more than the supported set of events */
> +	if (val > MAX_EVT_CONFIG_BITS) {
> +		rdt_last_cmd_puts("Invalid event configuration\n");
> +		return -EINVAL;
> +	}
> +
> +	cpus_read_lock();
> +
> +	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL)) {
> +		rdt_last_cmd_puts("cpu_mask allocation failed\n");
> +		ret = -ENOMEM;
> +		goto e_unlock;
> +	}
> +
> +	/*
> +	 * Read the current config value first. If both are same then
> +	 * we dont need to write it again.
> +	 */
> +	mon_info.evtid = evtid;
> +	mondata_config_read(d, &mon_info);
> +	if (mon_info.mon_config == val)
> +		goto e_cpumask;
> +
> +	mon_info.mon_config = val;
> +
> +	/* Pick all the CPUs in the domain instance */
> +	for_each_cpu(cpu, &d->cpu_mask)
> +		cpumask_set_cpu(cpu, cpu_mask);
> +
> +	/* Update MSR_IA32_EVT_CFG_BASE MSR on all the CPUs in cpu_mask
> */
> +	on_each_cpu_mask(cpu_mask, mon_event_config_write, &mon_info,
> 1);
> +
> +	/*
> +	 * When an Event Configuration is changed, the bandwidth counters
> +	 * for all RMIDs and Events will be cleared by the hardware. The
> +	 * hardware also sets MSR_IA32_QM_CTR.Unavailable (bit 62) for
> +	 * every RMID on the next read to any event for every RMID.
> +	 * Subsequent reads will have MSR_IA32_QM_CTR.Unavailable (bit 62)
> +	 * cleared while it is tracked by the hardware. Clear the
> +	 * mbm_local and mbm_total counts for all the RMIDs.
> +	 */
> +	memset(d->mbm_local, 0, sizeof(struct mbm_state) * r->num_rmid);
> +	memset(d->mbm_total, 0, sizeof(struct mbm_state) * r->num_rmid);
> +
> +e_cpumask:
> +	free_cpumask_var(cpu_mask);
> +
> +e_unlock:
> +	cpus_read_unlock();
> +
> +	return ret;
> +}
> +
> +unsigned int mon_config_parse(struct rdt_resource *r, char *tok, u32
> +evtid) {

Should this function be static?

> +	char *dom_str = NULL, *id_str;
> +	struct rdt_domain *d;
> +	unsigned long dom_id, val;
> +	int ret = 0;
> +
> +next:
> +	if (!tok || tok[0] == '\0')
> +		return 0;
> +
> +	/* Start processing the strings for each domain */
> +	dom_str = strim(strsep(&tok, ";"));
> +	id_str = strsep(&dom_str, "=");
> +
> +	if (!dom_str || kstrtoul(id_str, 10, &dom_id)) {
> +		rdt_last_cmd_puts("Missing '=' or non-numeric domain id\n");
> +		return -EINVAL;
> +	}
> +
> +	if (!dom_str || kstrtoul(dom_str, 16, &val)) {
> +		rdt_last_cmd_puts("Missing '=' or non-numeric event
> configuration value\n");
> +		return -EINVAL;
> +	}
> +
> +	list_for_each_entry(d, &r->domains, list) {
> +		if (d->id == dom_id) {
> +			ret = mbm_config_write(r, d, evtid, val);
> +			if (ret)
> +				return -EINVAL;
> +			goto next;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static ssize_t mbm_total_config_write(struct kernfs_open_file *of,
> +				      char *buf, size_t nbytes, loff_t off) {
> +	struct rdt_resource *r = of->kn->parent->priv;
> +	int ret;
> +
> +	/* Valid input requires a trailing newline */
> +	if (nbytes == 0 || buf[nbytes - 1] != '\n')
> +		return -EINVAL;
> +
> +	rdt_last_cmd_clear();
> +
> +	buf[nbytes - 1] = '\0';
> +
> +	ret = mon_config_parse(r, buf, QOS_L3_MBM_TOTAL_EVENT_ID);
> +
> +	return ret ?: nbytes;
> +}
> +
>  /* rdtgroup information files for one cache resource. */  static struct rftype
> res_common_files[] = {
>  	{
> @@ -1594,6 +1732,7 @@ static struct rftype res_common_files[] = {
>  		.mode		= 0644,
>  		.kf_ops		= &rdtgroup_kf_single_ops,
>  		.seq_show	= mbm_total_config_show,
> +		.write		= mbm_total_config_write,
>  	},
>  	{
>  		.name		= "mbm_local_config",
> 

Thanks.

-Fenghua