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

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Hi Fenghua,


> -----Original Message-----
> From: Yu, Fenghua <fenghua.yu@xxxxxxxxx>
> Sent: Tuesday, September 27, 2022 5:32 PM
> To: Moger, Babu <Babu.Moger@xxxxxxx>; corbet@xxxxxxx; Chatre, Reinette
> <reinette.chatre@xxxxxxxxx>; tglx@xxxxxxxxxxxxx; mingo@xxxxxxxxxx;
> bp@xxxxxxxxx
> Cc: dave.hansen@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx; hpa@xxxxxxxxx;
> paulmck@xxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; quic_neeraju@xxxxxxxxxxx;
> rdunlap@xxxxxxxxxxxxx; damien.lemoal@xxxxxxxxxxxxxxxxxx;
> songmuchun@xxxxxxxxxxxxx; peterz@xxxxxxxxxxxxx; jpoimboe@xxxxxxxxxx;
> pbonzini@xxxxxxxxxx; Bae, Chang Seok <chang.seok.bae@xxxxxxxxx>;
> pawan.kumar.gupta@xxxxxxxxxxxxxxx; jmattson@xxxxxxxxxx;
> daniel.sneddon@xxxxxxxxxxxxxxx; Das1, Sandipan <Sandipan.Das@xxxxxxx>;
> Luck, Tony <tony.luck@xxxxxxxxx>; james.morse@xxxxxxx; linux-
> doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; bagasdotme@xxxxxxxxx;
> Eranian, Stephane <eranian@xxxxxxxxxx>
> Subject: RE: [PATCH v5 09/12] x86/resctrl: Add sysfs interface to write
> mbm_total_bytes event configuration
> 
> 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?

Sure.
> 
> > +	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?

Sure. Thanks
Babu
> 
> > +	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




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