[PATCH] x86/resctrl: Fix WARN in get_domain_from_cpu()
From: Tony Luck
Date: Tue Feb 20 2024 - 19:35:40 EST
reset_all_ctrls() and resctrl_arch_update_domains() use
on_each_cpu_mask() to call rdt_ctrl_update() on potentially
one CPU from each domain.
But this means rdt_ctrl_update() needs to figure out which domain
to apply changes to. Doing so requires a search of all domains
in a resource, which can only be done safely if cpus_lock is
held. Both callers do hold this lock, but there isn't a way
for a function called on another CPU via IPI to verify this.
Fix by adding the target domain to the msr_param structure and
calling for each domain separately using smp_call_function_single()
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
Either apply on top of tip x86/cache:
fb700810d30b ("x86/resctrl: Separate arch and fs resctrl locks")
or merge this into that commit.
---
arch/x86/kernel/cpu/resctrl/internal.h | 1 +
arch/x86/kernel/cpu/resctrl/core.c | 10 +----
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 50 +++++------------------
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 14 ++-----
4 files changed, 16 insertions(+), 59 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c99f26ebe7a6..c30d7697b431 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -383,6 +383,7 @@ static inline struct rdt_hw_domain *resctrl_to_arch_dom(struct rdt_domain *r)
*/
struct msr_param {
struct rdt_resource *res;
+ struct rdt_domain *dom;
u32 low;
u32 high;
};
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 8a4ef4f5bddc..8d8b8abcda98 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -390,16 +390,8 @@ void rdt_ctrl_update(void *arg)
struct msr_param *m = arg;
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(m->res);
struct rdt_resource *r = m->res;
- int cpu = smp_processor_id();
- struct rdt_domain *d;
- d = get_domain_from_cpu(cpu, r);
- if (d) {
- hw_res->msr_update(d, m, r);
- return;
- }
- pr_warn_once("cpu %d not found in any domain for resource %s\n",
- cpu, r->name);
+ hw_res->msr_update(m->dom, m, r);
}
/*
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 7997b47743a2..aed702d06314 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -272,22 +272,6 @@ static u32 get_config_index(u32 closid, enum resctrl_conf_type type)
}
}
-static bool apply_config(struct rdt_hw_domain *hw_dom,
- struct resctrl_staged_config *cfg, u32 idx,
- cpumask_var_t cpu_mask)
-{
- struct rdt_domain *dom = &hw_dom->d_resctrl;
-
- if (cfg->new_ctrl != hw_dom->ctrl_val[idx]) {
- cpumask_set_cpu(cpumask_any(&dom->cpu_mask), cpu_mask);
- hw_dom->ctrl_val[idx] = cfg->new_ctrl;
-
- return true;
- }
-
- return false;
-}
-
int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_domain *d,
u32 closid, enum resctrl_conf_type t, u32 cfg_val)
{
@@ -315,17 +299,13 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
struct rdt_hw_domain *hw_dom;
struct msr_param msr_param;
enum resctrl_conf_type t;
- cpumask_var_t cpu_mask;
struct rdt_domain *d;
+ int cpu;
u32 idx;
/* Walking r->domains, ensure it can't race with cpuhp */
lockdep_assert_cpus_held();
- if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
- return -ENOMEM;
-
- msr_param.res = NULL;
list_for_each_entry(d, &r->domains, list) {
hw_dom = resctrl_to_arch_dom(d);
for (t = 0; t < CDP_NUM_TYPES; t++) {
@@ -334,29 +314,19 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
continue;
idx = get_config_index(closid, t);
- if (!apply_config(hw_dom, cfg, idx, cpu_mask))
+ if (cfg->new_ctrl == hw_dom->ctrl_val[idx])
continue;
-
- if (!msr_param.res) {
- msr_param.low = idx;
- msr_param.high = msr_param.low + 1;
- msr_param.res = r;
- } else {
- msr_param.low = min(msr_param.low, idx);
- msr_param.high = max(msr_param.high, idx + 1);
- }
+ hw_dom->ctrl_val[idx] = cfg->new_ctrl;
+ cpu = cpumask_any(&d->cpu_mask);
+
+ msr_param.low = idx;
+ msr_param.high = msr_param.low + 1;
+ msr_param.res = r;
+ msr_param.dom = d;
+ smp_call_function_single(cpu, rdt_ctrl_update, &msr_param, 1);
}
}
- if (cpumask_empty(cpu_mask))
- goto done;
-
- /* Update resource control msr on all the CPUs. */
- on_each_cpu_mask(cpu_mask, rdt_ctrl_update, &msr_param, 1);
-
-done:
- free_cpumask_var(cpu_mask);
-
return 0;
}
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 011e17efb1a6..da4f13db4161 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2813,16 +2813,13 @@ static int reset_all_ctrls(struct rdt_resource *r)
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
struct rdt_hw_domain *hw_dom;
struct msr_param msr_param;
- cpumask_var_t cpu_mask;
struct rdt_domain *d;
+ int cpu;
int i;
/* Walking r->domains, ensure it can't race with cpuhp */
lockdep_assert_cpus_held();
- if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
- return -ENOMEM;
-
msr_param.res = r;
msr_param.low = 0;
msr_param.high = hw_res->num_closid;
@@ -2834,17 +2831,14 @@ static int reset_all_ctrls(struct rdt_resource *r)
*/
list_for_each_entry(d, &r->domains, list) {
hw_dom = resctrl_to_arch_dom(d);
- cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
+ cpu = cpumask_any(&d->cpu_mask);
for (i = 0; i < hw_res->num_closid; i++)
hw_dom->ctrl_val[i] = r->default_ctrl;
+ msr_param.dom = d;
+ smp_call_function_single(cpu, rdt_ctrl_update, &msr_param, 1);
}
- /* Update CBM on all the CPUs in cpu_mask */
- on_each_cpu_mask(cpu_mask, rdt_ctrl_update, &msr_param, 1);
-
- free_cpumask_var(cpu_mask);
-
return 0;
}
--
2.43.0