Re: [PATCH v7 07/12] x86/resctrl: Add sysfs interface to read mbm_total_bytes event configuration

Moger, Babu
2022-10-26T19:36:31Z

Hi Reinette,

On 10/25/22 18:47, Reinette Chatre wrote:
> Hi Babu,
>
> On 10/17/2022 3:26 PM, Babu Moger wrote:
>> The current event configuration can be viewed by the user by reading
>> the configuration file /sys/fs/resctrl/info/L3_MON/mbm_total_config.
>> The event configuration settings are domain specific and will affect all
>> the CPUs in the domain.
>>
>> Following are the types of events supported:
>> ==== ===========================================================
>> Bits Description
>> ==== ===========================================================
>> 6 Dirty Victims from the QOS domain to all types of memory
>> 5 Reads to slow memory in the non-local NUMA domain
>> 4 Reads to slow memory in the local NUMA domain
>> 3 Non-temporal writes to non-local NUMA domain
>> 2 Non-temporal writes to local NUMA domain
>> 1 Reads to memory in the non-local NUMA domain
>> 0 Reads to memory in the local NUMA domain
>> ==== ===========================================================
>>
>> By default, the mbm_total_bytes configuration is set to 0x7f to count
>> all the event types.
>>
>> For example:
>> $cat /sys/fs/resctrl/info/L3_MON/mbm_total_config
>> 0=0x7f;1=0x7f;2=0x7f;3=0x7f
>>
>> In this case, the event mbm_total_bytes is currently configured
>> with 0x7f on domains 0 to 3.
>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
>> arch/x86/kernel/cpu/resctrl/core.c | 3 +
>> arch/x86/kernel/cpu/resctrl/internal.h | 2 +
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 76 ++++++++++++++++++++++++++++++++
>> 3 files changed, 81 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
>> index 46813b1c50c2..758c5d7553a4 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -826,6 +826,9 @@ static __init bool get_rdt_mon_resources(void)
>> if (!rdt_mon_features)
>> return false;
>>
>> + if (mon_configurable)
>> + mbm_config_rftype_init();
>> +
> Please move this to be within rdt_get_mon_l3_config().
Sure.
>
>> return !rdt_get_mon_l3_config(r, mon_configurable);
>> }
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index b458f768f30c..326a1b582f38 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -15,6 +15,7 @@
>> #define MSR_IA32_MBA_THRTL_BASE 0xd50
>> #define MSR_IA32_MBA_BW_BASE 0xc0000200
>> #define MSR_IA32_SMBA_BW_BASE 0xc0000280
>> +#define MSR_IA32_EVT_CFG_BASE 0xc0000400
>>
>> #define MSR_IA32_QM_CTR 0x0c8e
>> #define MSR_IA32_QM_EVTSEL 0x0c8d
>> @@ -541,5 +542,6 @@ bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
>> void __check_limbo(struct rdt_domain *d, bool force_free);
>> void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
>> void __init thread_throttle_mode_init(void);
>> +void __init mbm_config_rftype_init(void);
>>
>> #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 5f0ef1bf4c78..0982845594d0 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -1423,6 +1423,67 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
>> return ret;
>> }
>>
>> +struct mon_config_info {
>> + u32 evtid;
>> + u32 mon_config;
>> +};
>> +
>> +static void mon_event_config_read(void *info)
>> +{
>> + struct mon_config_info *mon_info = info;
>> + u32 h, 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;
>> + }
>> +
>> + rdmsr(MSR_IA32_EVT_CFG_BASE + msr_index, mon_info->mon_config, h);
>> +}
>> +
>> +static void mondata_config_read(struct rdt_domain *d, struct mon_config_info *mon_info)
>> +{
>> + smp_call_function_any(&d->cpu_mask, mon_event_config_read, mon_info, 1);
>> +}
>> +
>> +static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid)
>> +{
>> + struct mon_config_info mon_info = {0};
>> + struct rdt_domain *dom;
>> + bool sep = false;
>> +
>> + list_for_each_entry(dom, &r->domains, list) {
> This is done with no protection ... I do not see anything preventing last CPU of
> a domain going offline around this time taking this domain with it while this code
> still tries to access its members.
>
> I think all of this needs protection with rdtgroup_mutex.
Yes. I agree. Will change it.
>
>> + if (sep)
>> + seq_puts(s, ";");
>> +
>> + mon_info.evtid = evtid;
>> + mondata_config_read(dom, &mon_info);
>> +
>> + seq_printf(s, "%d=0x%02x", dom->id, mon_info.mon_config);
> It does not seem robust to me to use printf field width to manage the data
> returned from hardware. At this time bits 0 - 6 are supported by hardware ...
> what happens if hardware starts using bit 7 for something?
> It seems to me that the mask introduced later needs to be pulled here to
> ensure that only the valid bits are handled.
Ok. Sure.
>
>> + sep = true;
>> + }
>> + seq_puts(s, "\n");
>> +
>> + return 0;
>> +}
>> +
>> +static int mbm_total_config_show(struct kernfs_open_file *of,
>> + struct seq_file *seq, void *v)
>> +{
>> + struct rdt_resource *r = of->kn->parent->priv;
>> +
>> + mbm_config_show(seq, r, QOS_L3_MBM_TOTAL_EVENT_ID);
>> +
>> + return 0;
>> +}
>> +
>> /* rdtgroup information files for one cache resource. */
>> static struct rftype res_common_files[] = {
>> {
>> @@ -1521,6 +1582,12 @@ static struct rftype res_common_files[] = {
>> .seq_show = max_threshold_occ_show,
>> .fflags = RF_MON_INFO | RFTYPE_RES_CACHE,
>> },
>> + {
>> + .name = "mbm_total_config",
>> + .mode = 0644,
>> + .kf_ops = &rdtgroup_kf_single_ops,
>> + .seq_show = mbm_total_config_show,
>> + },
> Please only make mode writable when there is support for it.

Ok.

Thanks

Babu

>
>> {
>> .name = "cpus",
>> .mode = 0644,
>> @@ -1627,6 +1694,15 @@ void __init thread_throttle_mode_init(void)
>> rft->fflags = RF_CTRL_INFO | RFTYPE_RES_MB;
>> }
>>
>> +void __init mbm_config_rftype_init(void)
>> +{
>> + struct rftype *rft;
>> +
>> + rft = rdtgroup_get_rftype_by_name("mbm_total_config");
>> + if (rft)
>> + rft->fflags = RF_MON_INFO | RFTYPE_RES_CACHE;
>> +}
>> +
>> /**
>> * rdtgroup_kn_mode_restrict - Restrict user access to named resctrl file
>> * @r: The resource group with which the file is associated.
>>
>>
>
> Reinette

--
Thanks
Babu Moger