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x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read()

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Depending on the number of monitors available, Arm's MPAM may need to
allocate a monitor prior to reading the counter value. Allocating a
contended resource may involve sleeping.

__check_limbo() and mon_event_count() each make multiple calls to
resctrl_arch_rmid_read(), to avoid extra work on contended systems,
the allocation should be valid for multiple invocations of
resctrl_arch_rmid_read().

The memory or hardware allocated is not specific to a domain.

Add arch hooks for this allocation, which need calling before
resctrl_arch_rmid_read(). The allocated monitor is passed to
resctrl_arch_rmid_read(), then freed again afterwards. The helper
can be called on any CPU, and can sleep.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-16-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
This commit is contained in:
James Morse 2024-02-13 18:44:29 +00:00 committed by Borislav Petkov (AMD)
parent 6fde1424f2
commit e557999f80
5 changed files with 55 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
arch/x86/include/asm/resctrl.h
View File

@ -136,6 +136,17 @@ static inline u32 resctrl_arch_rmid_idx_encode(u32 ignored, u32 rmid)
return rmid;
}
/* x86 can always read an rmid, nothing needs allocating */
struct rdt_resource;
static inline void *resctrl_arch_mon_ctx_alloc(struct rdt_resource *r, int evtid)
{
might_sleep();
return NULL;
};
static inline void resctrl_arch_mon_ctx_free(struct rdt_resource *r, int evtid,
void *ctx) { };
void resctrl_cpu_detect(struct cpuinfo_x86 *c);
#else

7
arch/x86/kernel/cpu/resctrl/ctrlmondata.c
View File

@ -546,6 +546,11 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
rr->d = d;
rr->val = 0;
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;
}
cpu = cpumask_any_housekeeping(&d->cpu_mask);
@ -559,6 +564,8 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
smp_call_function_any(&d->cpu_mask, mon_event_count, rr, 1);
else
smp_call_on_cpu(cpu, smp_mon_event_count, rr, false);
resctrl_arch_mon_ctx_free(r, evtid, rr->arch_mon_ctx);
}
int rdtgroup_mondata_show(struct seq_file *m, void *arg)

1
arch/x86/kernel/cpu/resctrl/internal.h
View File

@ -137,6 +137,7 @@ struct rmid_read {
bool first;
int err;
u64 val;
void *arch_mon_ctx;
};
extern bool rdt_alloc_capable;

35
arch/x86/kernel/cpu/resctrl/monitor.c
View File

@ -269,7 +269,7 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,
u32 unused, u32 rmid, enum resctrl_event_id eventid,
u64 *val)
u64 *val, void *ignored)
{
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
@ -324,9 +324,17 @@ void __check_limbo(struct rdt_domain *d, bool force_free)
u32 idx_limit = resctrl_arch_system_num_rmid_idx();
struct rmid_entry *entry;
u32 idx, cur_idx = 1;
void *arch_mon_ctx;
bool rmid_dirty;
u64 val = 0;
arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, QOS_L3_OCCUP_EVENT_ID);
if (IS_ERR(arch_mon_ctx)) {
pr_warn_ratelimited("Failed to allocate monitor context: %ld",
PTR_ERR(arch_mon_ctx));
return;
}
/*
* Skip RMID 0 and start from RMID 1 and check all the RMIDs that
* are marked as busy for occupancy < threshold. If the occupancy
@ -340,7 +348,8 @@ void __check_limbo(struct rdt_domain *d, bool force_free)
entry = __rmid_entry(idx);
if (resctrl_arch_rmid_read(r, d, entry->closid, entry->rmid,
QOS_L3_OCCUP_EVENT_ID, &val)) {
QOS_L3_OCCUP_EVENT_ID, &val,
arch_mon_ctx)) {
rmid_dirty = true;
} else {
rmid_dirty = (val >= resctrl_rmid_realloc_threshold);
@ -353,6 +362,8 @@ void __check_limbo(struct rdt_domain *d, bool force_free)
}
cur_idx = idx + 1;
}
resctrl_arch_mon_ctx_free(r, QOS_L3_OCCUP_EVENT_ID, arch_mon_ctx);
}
bool has_busy_rmid(struct rdt_domain *d)
@ -533,7 +544,7 @@ static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)
}
rr->err = resctrl_arch_rmid_read(rr->r, rr->d, closid, rmid, rr->evtid,
&tval);
&tval, rr->arch_mon_ctx);
if (rr->err)
return rr->err;
@ -722,11 +733,27 @@ static void mbm_update(struct rdt_resource *r, struct rdt_domain *d,
if (is_mbm_total_enabled()) {
rr.evtid = QOS_L3_MBM_TOTAL_EVENT_ID;
rr.val = 0;
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(closid, rmid, &rr);
resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
}
if (is_mbm_local_enabled()) {
rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID;
rr.val = 0;
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(closid, rmid, &rr);
/*
@ -736,6 +763,8 @@ static void mbm_update(struct rdt_resource *r, struct rdt_domain *d,
*/
if (is_mba_sc(NULL))
mbm_bw_count(closid, rmid, &rr);
resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
}
}

5
include/linux/resctrl.h
View File

@ -235,6 +235,9 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);
* @rmid: rmid of the counter to read.
* @eventid: eventid to read, e.g. L3 occupancy.
* @val: result of the counter read in bytes.
* @arch_mon_ctx: An architecture specific value from
* resctrl_arch_mon_ctx_alloc(), for MPAM this identifies
* the hardware monitor allocated for this read request.
*
* Some architectures need to sleep when first programming some of the counters.
* (specifically: arm64's MPAM cache occupancy counters can return 'not ready'
@ -248,7 +251,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);
*/
int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,
u32 closid, u32 rmid, enum resctrl_event_id eventid,
u64 *val);
u64 *val, void *arch_mon_ctx);
/**
* resctrl_arch_rmid_read_context_check() - warn about invalid contexts