Hi Reinette, On 7/17/25 22:53, Reinette Chatre wrote: > Hi Babu, > > On 7/8/25 3:17 PM, Babu Moger wrote: >> When "mbm_event" counter assignment mode is enabled, the architecture >> requires a counter ID to read the event data. >> >> Introduce an is_cntr field in struct rmid_read to indicate whether counter >> assignment mode is in use. >> >> Update the logic to call resctrl_arch_cntr_read() and >> resctrl_arch_reset_cntr() when the assignment mode is active. >> >> Declare mbm_cntr_get() in fs/resctrl/internal.h to make it accessible to >> other functions within fs/resctrl. >> >> Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> >> Signed-off-by: Babu Moger <babu.moger@xxxxxxx> >> --- >> v15: New patch to add is_cntr in rmid_read as discussed in >> https://lore.kernel.org/lkml/b4b14670-9cb0-4f65-abd5-39db996e8da9@xxxxxxxxx/ >> --- >> fs/resctrl/ctrlmondata.c | 8 ++++++++ >> fs/resctrl/internal.h | 5 +++++ >> fs/resctrl/monitor.c | 42 +++++++++++++++++++++++++++++++++------- >> 3 files changed, 48 insertions(+), 7 deletions(-) >> >> diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c >> index ad7ffc6acf13..ce766b2cdfc1 100644 >> --- a/fs/resctrl/ctrlmondata.c >> +++ b/fs/resctrl/ctrlmondata.c >> @@ -569,6 +569,14 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r, >> return; >> } >> >> + if (resctrl_arch_mbm_cntr_assign_enabled(r) && resctrl_is_mbm_event(evtid)) { >> + if (mbm_cntr_get(r, d, rdtgrp, evtid) < 0) { >> + rr->err = -ENOENT; > > This introduces the new -ENOENT error code but rdtgroup_mondata_show() is not enabled to > handle it. Looks like the next patch needs to be squashed into this one. Sure. > >> + return; > > Looking at this closer this does not seem the right place for this check. This is the > top level mon_event_read() when the user reads an event file. If this is an event > associated with a CTRL_MON group then resctrl should sum the data of the CTRL_MON group > and all of its MON groups. > It may be that the CTRL_MON group's event does not have a counter assigned, but one > or more of the MON groups do. In this case I do not think resctrl should fail reading > the CTRL_MON's event early as is done above but still provide the sum of the events that > can be counted in the MON groups that do have counters assigned. With that, only return > "Unassigned" if no counter is assigned in any CTRL_MON or MON group? Yes. Very good point. Thanks Changed the code to just set is_mbm_cntr here. > > > There also appears to be potential for a leak here with the early exit without calling > resctrl_arch_mon_ctx_free(). As mentioned earlier in series I do not think that > arch_mon_ctx is relevant to this counter assignment so I think mbm_update_one_event() > as well as mon_event_read() should make calling resctrl_arch_mon_ctx_alloc() > conditional on is_cntr/is_mbm_cntr. Sure. > > >> + } >> + rr->is_cntr = true; >> + } >> + >> cpu = cpumask_any_housekeeping(cpumask, RESCTRL_PICK_ANY_CPU); >> >> /* >> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h >> index 647a0466ffa0..fb4fec4a4cdc 100644 >> --- a/fs/resctrl/internal.h >> +++ b/fs/resctrl/internal.h >> @@ -110,6 +110,8 @@ struct mon_data { >> * domains in @r sharing L3 @ci.id >> * @evtid: Which monitor event to read. >> * @first: Initialize MBM counter when true. >> + * @is_cntr: Is the counter valid? true if "mbm_event" counter assignment mode is >> + * enabled and it is an MBM event. >> * @ci_id: Cacheinfo id for L3. Only set when @d is NULL. Used when summing domains. >> * @err: Error encountered when reading counter. >> * @val: Returned value of event counter. If @rgrp is a parent resource group, >> @@ -124,6 +126,7 @@ struct rmid_read { >> struct rdt_mon_domain *d; >> enum resctrl_event_id evtid; >> bool first; >> + bool is_cntr; > > After seeing how this all comes together the "is_cntr" is very generic and not > matching the often used "mbm_cntr". What do you think of "is_mbm_cntr"? Sure. > >> unsigned int ci_id; >> int err; >> u64 val; >> @@ -391,6 +394,8 @@ int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp >> struct mon_evt *mevt); >> void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp, >> struct mon_evt *mevt); >> +int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d, >> + struct rdtgroup *rdtgrp, enum resctrl_event_id evtid); >> >> #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK >> int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp); >> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c >> index 73f507942b6d..35faca7ff3b1 100644 >> --- a/fs/resctrl/monitor.c >> +++ b/fs/resctrl/monitor.c >> @@ -366,9 +366,21 @@ static int __mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr) >> struct mbm_state *m; >> int err, ret; >> u64 tval = 0; >> + int cntr_id; > > I've tried a couple of checkers and not all can pick up that cntr_id is always > assigned when it is used below. While it is not necessary it will be helpful to > initialize cntr_id here (-ENOENT?) just to avoid needing to prove that hypothetical > reports from these checkers are false positives. Yes. > >> + >> + if (rr->is_cntr) { >> + cntr_id = mbm_cntr_get(rr->r, rr->d, rdtgrp, rr->evtid); >> + if (cntr_id < 0) { >> + rr->err = -ENOENT; >> + return -EINVAL; >> + } > > This looks to be the right place for the mbm_cntr_get() check. Just keeping this one > avoids the duplication while also makeing the code match existing user ABI. > What do you think? That is perfect actually. > >> + } >> >> if (rr->first) { >> - resctrl_arch_reset_rmid(rr->r, rr->d, closid, rmid, rr->evtid); >> + if (rr->is_cntr) >> + resctrl_arch_reset_cntr(rr->r, rr->d, closid, rmid, cntr_id, rr->evtid); >> + else >> + resctrl_arch_reset_rmid(rr->r, rr->d, closid, rmid, rr->evtid); >> m = get_mbm_state(rr->d, closid, rmid, rr->evtid); >> if (m) >> memset(m, 0, sizeof(struct mbm_state)); >> @@ -379,8 +391,12 @@ static int __mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr) >> /* Reading a single domain, must be on a CPU in that domain. */ >> if (!cpumask_test_cpu(cpu, &rr->d->hdr.cpu_mask)) >> return -EINVAL; >> - rr->err = resctrl_arch_rmid_read(rr->r, rr->d, closid, rmid, >> - rr->evtid, &tval, rr->arch_mon_ctx); >> + if (rr->is_cntr) >> + rr->err = resctrl_arch_cntr_read(rr->r, rr->d, closid, rmid, cntr_id, >> + rr->evtid, &tval, rr->arch_mon_ctx); >> + else >> + rr->err = resctrl_arch_rmid_read(rr->r, rr->d, closid, rmid, >> + rr->evtid, &tval, rr->arch_mon_ctx); >> if (rr->err) >> return rr->err; >> >> @@ -405,8 +421,12 @@ static int __mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr) >> list_for_each_entry(d, &rr->r->mon_domains, hdr.list) { >> if (d->ci_id != rr->ci_id) >> continue; >> - err = resctrl_arch_rmid_read(rr->r, d, closid, rmid, >> - rr->evtid, &tval, rr->arch_mon_ctx); >> + if (rr->is_cntr) >> + err = resctrl_arch_cntr_read(rr->r, d, closid, rmid, cntr_id, >> + rr->evtid, &tval, rr->arch_mon_ctx); >> + else >> + err = resctrl_arch_rmid_read(rr->r, d, closid, rmid, >> + rr->evtid, &tval, rr->arch_mon_ctx); >> if (!err) { >> rr->val += tval; >> ret = 0; >> @@ -620,6 +640,14 @@ static void mbm_update_one_event(struct rdt_resource *r, struct rdt_mon_domain * >> return; >> } >> >> + if (resctrl_arch_mbm_cntr_assign_enabled(r) && resctrl_is_mbm_event(evtid)) { >> + if (mbm_cntr_get(r, d, rdtgrp, evtid) < 0) { >> + rr.err = -ENOENT; >> + return; >> + } > > This can be dropped also? Only is_cntr/is_mbm_cntr needs to be set here, __mon_event_count() > called below duplicates above snippet and will set rr->err Sure. > > Same comment here about missing call to resctrl_arch_mon_ctx_free(). Sure. > > >> + rr.is_cntr = true; >> + } >> + >> __mon_event_count(rdtgrp, &rr); >> >> /* >> @@ -982,8 +1010,8 @@ static void resctrl_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d >> * Return: >> * Valid counter ID on success, or -ENOENT on failure. >> */ >> -static int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d, >> - struct rdtgroup *rdtgrp, enum resctrl_event_id evtid) >> +int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d, >> + struct rdtgroup *rdtgrp, enum resctrl_event_id evtid) >> { >> int cntr_id; >> > > Reinette > -- Thanks Babu Moger
