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Date: Fri, 24 Sep 2021 06:34:55 +0000
From: "tan.shaopeng@...itsu.com" <tan.shaopeng@...itsu.com>
To: 'James Morse' <james.morse@....com>,
"'x86@...nel.org'" <x86@...nel.org>,
"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
CC: 'Fenghua Yu' <fenghua.yu@...el.com>,
'Reinette Chatre' <reinette.chatre@...el.com>,
'Thomas Gleixner' <tglx@...utronix.de>,
'Ingo Molnar' <mingo@...hat.com>,
'Borislav Petkov' <bp@...en8.de>,
'H Peter Anvin' <hpa@...or.com>,
'Babu Moger' <Babu.Moger@....com>,
"'shameerali.kolothum.thodi@...wei.com'"
<shameerali.kolothum.thodi@...wei.com>,
'Jamie Iles' <jamie@...iainc.com>,
'D Scott Phillips OS' <scott@...amperecomputing.com>,
"'lcherian@...vell.com'" <lcherian@...vell.com>,
"'bobo.shaobowang@...wei.com'" <bobo.shaobowang@...wei.com>,
"tan.shaopeng@...itsu.com" <tan.shaopeng@...itsu.com>
Subject: RE: [PATCH v1 13/20] x86/recstrl: Allow per-rmid arch private storage
to be reset
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@....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
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