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fs/resctrl: Support counter read/reset with mbm_event assignment mode

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When "mbm_event" counter assignment mode is enabled, the architecture requires
a counter ID to read the event data.

Introduce an is_mbm_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. Report 'Unassigned' in case the user attempts
to read an event without assigning a hardware counter.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com
This commit is contained in:
Babu Moger 2025-09-05 16:34:22 -05:00 • committed by Borislav Petkov (AMD)
parent 2a65b72c16
commit 159f36cd4d
4 changed files with 62 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

6
Documentation/filesystems/resctrl.rst
View file

@ -434,6 +434,12 @@ When monitoring is enabled all MON groups will also contain:
for the L3 cache they occupy). These are named "mon_sub_L3_YY"
where "YY" is the node number.
When the 'mbm_event' counter assignment mode is enabled, reading
an MBM event of a MON group returns 'Unassigned' if no hardware
counter is assigned to it. For CTRL_MON groups, 'Unassigned' is
returned if the MBM event does not have an assigned counter in the
CTRL_MON group nor in any of its associated MON groups.
"mon_hw_id":
Available only with debug option. The identifier used by hardware
for the monitor group. On x86 this is the RMID.

22
fs/resctrl/ctrlmondata.c
View file

@ -563,10 +563,15 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
rr->r = r;
rr->d = d;
rr->first = first;
rr->arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, evtid);
if (IS_ERR(rr->arch_mon_ctx)) {
rr->err = -EINVAL;
return;
if (resctrl_arch_mbm_cntr_assign_enabled(r) &&
resctrl_is_mbm_event(evtid)) {
rr->is_mbm_cntr = true;
} else {
rr->arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, evtid);
if (IS_ERR(rr->arch_mon_ctx)) {
rr->err = -EINVAL;
return;
}
}
cpu = cpumask_any_housekeeping(cpumask, RESCTRL_PICK_ANY_CPU);
@ -582,7 +587,8 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
else
smp_call_on_cpu(cpu, smp_mon_event_count, rr, false);
resctrl_arch_mon_ctx_free(r, evtid, rr->arch_mon_ctx);
if (rr->arch_mon_ctx)
resctrl_arch_mon_ctx_free(r, evtid, rr->arch_mon_ctx);
}
int rdtgroup_mondata_show(struct seq_file *m, void *arg)
@ -653,10 +659,16 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
checkresult:
/*
* -ENOENT is a special case, set only when "mbm_event" counter assignment
* mode is enabled and no counter has been assigned.
*/
if (rr.err == -EIO)
seq_puts(m, "Error\n");
else if (rr.err == -EINVAL)
seq_puts(m, "Unavailable\n");
else if (rr.err == -ENOENT)
seq_puts(m, "Unassigned\n");
else
seq_printf(m, "%llu\n", rr.val);

3
fs/resctrl/internal.h
View file

@ -111,6 +111,8 @@ struct mon_data {
* @evtid: Which monitor event to read.
* @first: Initialize MBM counter when true.
* @ci: Cacheinfo for L3. Only set when @d is NULL. Used when summing domains.
* @is_mbm_cntr: true if "mbm_event" counter assignment mode is enabled and it
* is an MBM event.
* @err: Error encountered when reading counter.
* @val: Returned value of event counter. If @rgrp is a parent resource group,
* @val includes the sum of event counts from its child resource groups.
@ -125,6 +127,7 @@ struct rmid_read {
enum resctrl_event_id evtid;
bool first;
struct cacheinfo *ci;
bool is_mbm_cntr;
int err;
u64 val;
void *arch_mon_ctx;

47
fs/resctrl/monitor.c
View file

@ -419,12 +419,24 @@ static int __mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
u32 closid = rdtgrp->closid;
u32 rmid = rdtgrp->mon.rmid;
struct rdt_mon_domain *d;
int cntr_id = -ENOENT;
struct mbm_state *m;
int err, ret;
u64 tval = 0;
if (rr->is_mbm_cntr) {
cntr_id = mbm_cntr_get(rr->r, rr->d, rdtgrp, rr->evtid);
if (cntr_id < 0) {
rr->err = -ENOENT;
return -EINVAL;
}
}
if (rr->first) {
resctrl_arch_reset_rmid(rr->r, rr->d, closid, rmid, rr->evtid);
if (rr->is_mbm_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));
@ -435,8 +447,12 @@ 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_mbm_cntr)
rr->err = resctrl_arch_cntr_read(rr->r, rr->d, closid, rmid, cntr_id,
rr->evtid, &tval);
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;
@ -460,8 +476,12 @@ 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_mbm_cntr)
err = resctrl_arch_cntr_read(rr->r, d, closid, rmid, cntr_id,
rr->evtid, &tval);
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;
@ -668,11 +688,15 @@ static void mbm_update_one_event(struct rdt_resource *r, struct rdt_mon_domain *
rr.r = r;
rr.d = d;
rr.evtid = evtid;
rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);
if (IS_ERR(rr.arch_mon_ctx)) {
pr_warn_ratelimited("Failed to allocate monitor context: %ld",
PTR_ERR(rr.arch_mon_ctx));
return;
if (resctrl_arch_mbm_cntr_assign_enabled(r)) {
rr.is_mbm_cntr = true;
} else {
rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);
if (IS_ERR(rr.arch_mon_ctx)) {
pr_warn_ratelimited("Failed to allocate monitor context: %ld",
PTR_ERR(rr.arch_mon_ctx));
return;
}
}
__mon_event_count(rdtgrp, &rr);
@ -684,7 +708,8 @@ static void mbm_update_one_event(struct rdt_resource *r, struct rdt_mon_domain *
if (is_mba_sc(NULL))
mbm_bw_count(rdtgrp, &rr);
resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
if (rr.arch_mon_ctx)
resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
}
static void mbm_update(struct rdt_resource *r, struct rdt_mon_domain *d,