RE: [PATCH v1 13/20] x86/recstrl: Allow per-rmid arch private storage to be reset

["tan.shaopeng@fujitsu.com" <tan.shaopeng@fujitsu.com>]

Hi James,

> To abstract the rmid counters into a helper that returns the number of bytes
> counted, architecture specific per-rmid state is needed.
> 
> It needs to be possible to reset this hidden state, as the values may outlive the
> life of an rmid, or the mount time of the filesystem.
> 
> mon_event_read() is called with first = true when an rmid is first allocated in
> mkdir_mondata_subdir(). Add resctrl_arch_reset_rmid() and call it from
> __mon_event_count()'s rr->first check.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
>  arch/x86/kernel/cpu/resctrl/internal.h | 18 ++++--------
> arch/x86/kernel/cpu/resctrl/monitor.c  | 38
> +++++++++++++++++++++-----
>  include/linux/resctrl.h                | 23 ++++++++++++++++
>  3 files changed, 59 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h
> b/arch/x86/kernel/cpu/resctrl/internal.h
> index aaae900a8ef3..f3f31315a907 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -22,14 +22,6 @@
> 
>  #define L2_QOS_CDP_ENABLE		0x01ULL
> 
> -/*
> - * Event IDs are used to program IA32_QM_EVTSEL before reading event
> - * counter from IA32_QM_CTR
> - */
> -#define QOS_L3_OCCUP_EVENT_ID		0x01
> -#define QOS_L3_MBM_TOTAL_EVENT_ID	0x02
> -#define QOS_L3_MBM_LOCAL_EVENT_ID	0x03
> -
>  #define CQM_LIMBOCHECK_INTERVAL	1000
> 
>  #define MBM_CNTR_WIDTH_BASE		24
> @@ -73,7 +65,7 @@ DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
>   * @list:		entry in &rdt_resource->evt_list
>   */
>  struct mon_evt {
> -	u32			evtid;
> +	enum resctrl_event_id	evtid;
>  	char			*name;
>  	struct list_head	list;
>  };
> @@ -90,9 +82,9 @@ struct mon_evt {
>  union mon_data_bits {
>  	void *priv;
>  	struct {
> -		unsigned int rid	: 10;
> -		unsigned int evtid	: 8;
> -		unsigned int domid	: 14;
> +		unsigned int rid		: 10;
> +		enum resctrl_event_id evtid	: 8;
> +		unsigned int domid		: 14;
>  	} u;
>  };
> 
> @@ -100,7 +92,7 @@ struct rmid_read {
>  	struct rdtgroup		*rgrp;
>  	struct rdt_resource	*r;
>  	struct rdt_domain	*d;
> -	int			evtid;
> +	enum resctrl_event_id	evtid;
>  	bool			first;
>  	u64			val;
>  };
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
> b/arch/x86/kernel/cpu/resctrl/monitor.c
> index af60e154f0ed..3b8b29470a5c 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -137,7 +137,34 @@ static inline struct rmid_entry *__rmid_entry(u32 rmid)
>  	return entry;
>  }
> 
> -static u64 __rmid_read(u32 rmid, u32 eventid)
> +static struct arch_mbm_state *get_arch_mbm_state(struct rdt_hw_domain
> *hw_dom,
> +						 u32 rmid,
> +						 enum resctrl_event_id
> eventid)
> +{
> +	switch (eventid) {
> +	case QOS_L3_OCCUP_EVENT_ID:
> +		return NULL;
> +	case QOS_L3_MBM_TOTAL_EVENT_ID:
> +		return &hw_dom->arch_mbm_total[rmid];
> +	case QOS_L3_MBM_LOCAL_EVENT_ID:
> +		return &hw_dom->arch_mbm_local[rmid];
> +	}
> +

Since it is unexpected to come here,
it might be better to add WARN_ON.

In addition, I have tested these patches on Intel(R) Xeon(R) Gold 6254 CPU with resctrl selftest. It is no problem.

Thanks,

Shaopeng Tan

> +	return NULL;
> +}
> +
> +void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d,
> +			     u32 rmid, enum resctrl_event_id eventid) {
> +	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
> +	struct arch_mbm_state *m;
> +
> +	m = get_arch_mbm_state(hw_dom, rmid, eventid);
> +	if (m)
> +		memset(m, 0, sizeof(*m));
> +}
> +
> +static u64 __rmid_read(u32 rmid, enum resctrl_event_id eventid)
>  {
>  	u64 val;
> 
> @@ -291,6 +318,9 @@ static int __mon_event_count(u32 rmid, struct
> rmid_read *rr)
>  	struct mbm_state *m;
>  	u64 chunks, tval;
> 
> +	if (rr->first)
> +		resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);
> +
>  	tval = __rmid_read(rmid, rr->evtid);
>  	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
>  		rr->val = tval;
> @@ -306,12 +336,6 @@ static int __mon_event_count(u32 rmid, struct
> rmid_read *rr)
>  	case QOS_L3_MBM_LOCAL_EVENT_ID:
>  		m = &rr->d->mbm_local[rmid];
>  		break;
> -	default:
> -		/*
> -		 * Code would never reach here because
> -		 * an invalid event id would fail the __rmid_read.
> -		 */
> -		return -EINVAL;
>  	}
> 
>  	if (rr->first) {
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index
> 4fe2d5500315..79e83ce3dfbc 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -32,6 +32,16 @@ enum resctrl_conf_type {
> 
>  #define CDP_NUM_TYPES	(CDP_DATA + 1)
> 
> +/*
> + * Event IDs, the values match those used to program IA32_QM_EVTSEL
> +before
> + * reading IA32_QM_CTR on RDT systems.
> + */
> +enum resctrl_event_id {
> +	QOS_L3_OCCUP_EVENT_ID		= 0x01,
> +	QOS_L3_MBM_TOTAL_EVENT_ID	= 0x02,
> +	QOS_L3_MBM_LOCAL_EVENT_ID	= 0x03,
> +};
> +
>  /**
>   * struct resctrl_staged_config - parsed configuration to be applied
>   * @new_ctrl:		new ctrl value to be loaded
> @@ -219,4 +229,17 @@ void resctrl_arch_get_config(struct rdt_resource *r,
> struct rdt_domain *d,  int resctrl_online_domain(struct rdt_resource *r, struct
> rdt_domain *d);  void resctrl_offline_domain(struct rdt_resource *r, struct
> rdt_domain *d);
> 
> +/**
> + * resctrl_arch_reset_rmid() - Reset any private state associated with rmid
> + *			       and eventid.
> + * @r:		The domain's resource.
> + * @d:		The rmid's domain.
> + * @rmid:	The rmid whose counter values should be reset.
> + * @eventid:	The eventid whose counter values should be reset.
> + *
> + * This can be called from any CPU.
> + */
> +void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d,
> +			     u32 rmid, enum resctrl_event_id eventid);
> +
>  #endif /* _RESCTRL_H */
> --
> 2.30.2