x86/resctrl: Pass domain to target CPU

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.

Commit

  c0d848fcb09d ("x86/resctrl: Remove lockdep annotation that triggers
  false positive")

removed the incorrect assertions.

Add the target domain to the msr_param structure and call
rdt_ctrl_update() for each domain separately using
smp_call_function_single(). This means that rdt_ctrl_update() doesn't
need to search for the domain and get_domain_from_cpu() can safely
assert that the cpus_lock is held since the remaining callers do not use
IPI.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://lore.kernel.org/r/20240308213846.77075-2-tony.luck@intel.com

1 files changed, 6 insertions, 11 deletions

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 83e40341583e..acf52aa185e0 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -362,6 +362,8 @@ struct rdt_domain *get_domain_from_cpu(int cpu, struct rdt_resource *r)
 {
 	struct rdt_domain *d;
 
+	lockdep_assert_cpus_held();
+
 	list_for_each_entry(d, &r->domains, list) {
 		/* Find the domain that contains this CPU */
 		if (cpumask_test_cpu(cpu, &d->cpu_mask))
@@ -378,19 +380,11 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r)
 
 void rdt_ctrl_update(void *arg)
 {
+	struct rdt_hw_resource *hw_res;
 	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 = resctrl_to_arch_res(m->res);
+	hw_res->msr_update(m->dom, m, m->res);
 }
 
 /*
@@ -463,6 +457,7 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)
 	hw_dom->ctrl_val = dc;
 	setup_default_ctrlval(r, dc);
 
+	m.dom = d;
 	m.low = 0;
 	m.high = hw_res->num_closid;
 	hw_res->msr_update(d, &m, r);