Re: [PATCH v3 08/10] x86/resctrl: Add the sysfs interface to read the event configuration

["Moger, Babu" <babu.moger@amd.com>]

On 8/24/22 16:16, Reinette Chatre wrote:
> Hi Babu,
>
> On 8/22/2022 6:44 AM, Babu Moger wrote:
>> The current event configuration can be viewed by the user by reading
>> the sysfs configuration file.
>>
>> 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 types of events and mbm_local_bytes configuration is set to
>> 0x15 to count all the local memory events.
>>
>> $cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_config
>> 0x7f
>>
>> $cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_config
>> 0x15
>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> Reviewed-by: Ingo Molnar <mingo@kernel.org>
>> ---
>>  arch/x86/kernel/cpu/resctrl/internal.h |   21 ++++++++++
>>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |   70 ++++++++++++++++++++++++++++++++
>>  2 files changed, 91 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index fc725f5e9024..457666709386 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
>> @@ -50,6 +51,26 @@
>>   */
>>  #define MBM_CNTR_WIDTH_OFFSET_MAX (62 - MBM_CNTR_WIDTH_BASE)
>>  
>> +/* Reads to Local DRAM Memory */
>> +#define READS_TO_LOCAL_MEM		BIT(0)
>> +
>> +/* Reads to Remote DRAM Memory */
>> +#define READS_TO_REMOTE_MEM		BIT(1)
>> +
>> +/* Non-Temporal Writes to Local Memory */
>> +#define NON_TEMP_WRITE_TO_LOCAL_MEM	BIT(2)
>> +
>> +/* Non-Temporal Writes to Remote Memory */
>> +#define NON_TEMP_WRITE_TO_REMOTE_MEM	BIT(3)
>> +
>> +/* Reads to Local Memory the system identifies as "Slow Memory" */
> Seems unexpected character slipped into "identifies".
Sure. Will fix it
>
>> +#define READS_TO_LOCAL_S_MEM		BIT(4)
>> +
>> +/* Reads to Remote Memory the system identifies as "Slow Memory" */
> here also
sure. Will fix it.
>
>> +#define READS_TO_REMOTE_S_MEM		BIT(5)
>> +
>> +/* Dirty Victims to All Types of Memory */
>> +#define  DIRTY_VICTIS_TO_ALL_MEM	BIT(6)
> Is this intended to be "DIRTY_VICTIMS_TO_ALL_MEM" ?
Yes. that is what spec says.
>
>>  
>>  struct rdt_fs_context {
>>  	struct kernfs_fs_context	kfc;
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 30d2182d4fda..e1847d49fa15 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -254,8 +254,78 @@ static const struct kernfs_ops kf_mondata_ops = {
>>  	.seq_show		= rdtgroup_mondata_show,
>>  };
>>  
>> +/*
>> + * This is called via IPI to read the CQM/MBM counters
>> + * in a domain.
>> + */
>> +void mon_event_config_read(void *info)
>> +{
>> +	union mon_data_bits *md = info;
>> +	u32 evtid = md->u.evtid;
>> +	u32 h, msr_index;
>> +
>> +	switch (evtid) {
>> +	case QOS_L3_MBM_TOTAL_EVENT_ID:
>> +		msr_index = 0;
>> +		break;
>> +	case QOS_L3_MBM_LOCAL_EVENT_ID:
>> +		msr_index = 1;
>> +		break;
>> +	default:
>> +		return; /* Not expected to come here */
> Please no inline comments.

Ok


>
>> +	}
>> +
>> +	rdmsr(MSR_IA32_EVT_CFG_BASE + msr_index, md->u.mon_config, h);
>> +}
>> +
>> +void mondata_config_read(struct rdt_domain *d, union mon_data_bits *md)
>> +{
>> +	smp_call_function_any(&d->cpu_mask, mon_event_config_read, md, 1);
>> +}
>> +
>> +int rdtgroup_mondata_config_show(struct seq_file *m, void *arg)
>> +{
>> +	struct kernfs_open_file *of = m->private;
>> +	struct rdt_hw_resource *hw_res;
>> +	u32 resid, evtid, domid;
>> +	struct rdtgroup *rdtgrp;
>> +	struct rdt_resource *r;
>> +	union mon_data_bits md;
>> +	struct rdt_domain *d;
>> +	int ret = 0;
>> +
>> +	rdtgrp = rdtgroup_kn_lock_live(of->kn);
>> +	if (!rdtgrp) {
>> +		ret = -ENOENT;
>> +		goto out;
>> +	}
>> +
>> +	md.priv = of->kn->priv;
>> +	resid = md.u.rid;
>> +	domid = md.u.domid;
>> +	evtid = md.u.evtid;
>> +
>> +	hw_res = &rdt_resources_all[resid];
>> +	r = &hw_res->r_resctrl;
>> +
>> +	d = rdt_find_domain(r, domid, NULL);
>> +	if (IS_ERR_OR_NULL(d)) {
>> +		ret = -ENOENT;
>> +		goto out;
>> +	}
>> +
>> +	mondata_config_read(d, &md);
>> +
>> +	seq_printf(m, "0x%x\n", md.u.mon_config);
> Looking at this patch and the next, the sysfs files are introduced to read
> from and write to the configuration register. From what I can tell the
> data is never used internally (what did I miss?). Why is the value of the
> configuration register stored? 

You didn't miss anything. We don't need to store it.  But we need it as
part of mon_data_bits structure because, it need to be passed to
mon_event_config_read and rdtgroup_mondata_config_write.

In these functions we need evtid and also config value (mon_config).

Thanks

Babu

>
>> +
>> +out:
>> +	rdtgroup_kn_unlock(of->kn);
>> +	return ret;
>> +}
>> +
>>  static const struct kernfs_ops kf_mondata_config_ops = {
>>  	.atomic_write_len       = PAGE_SIZE,
>> +	.seq_show               = rdtgroup_mondata_config_show,
>>  };
>>  
>>  static bool is_cpu_list(struct kernfs_open_file *of)
>>
>>
>
> Reinette

-- 
Thanks
Babu Moger