[PATCH v7 10/49] x86/resctrl: Remove rdtgroup from update_cpu_closid_rmid()

James Morse
2025-02-28T20:00:35Z

update_cpu_closid_rmid() takes a struct rdtgroup as an argument, which
it uses to update the local CPUs default pqr values. This is a problem
once the resctrl parts move out to /fs/, as the arch code cannot
poke around inside struct rdtgroup.

Rename update_cpu_closid_rmid() as resctrl_arch_sync_cpus_defaults()
to be used as the target of an IPI, and pass the effective CLOSID
and RMID in a new struct.

Co-developed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
---
Changes since v1:
* To clarify the meanings of the new helper and struct:

Rename resctrl_arch_sync_cpu_default() to
resctrl_arch_sync_cpu_closid_rmid();

Rename struct resctrl_cpu_sync to struct resctrl_cpu_defaults;

Flesh out the comment block in <linux/resctrl.h>.

No functional change.
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 17 +++++++++++++----
include/linux/resctrl.h | 22 ++++++++++++++++++++++
2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index f706e5a288b1..62d9a50c7bba 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -355,13 +355,13 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
* from update_closid_rmid() is protected against __switch_to() because
* preemption is disabled.
*/
-static void update_cpu_closid_rmid(void *info)
+void resctrl_arch_sync_cpu_closid_rmid(void *info)
{
- struct rdtgroup *r = info;
+ struct resctrl_cpu_defaults *r = info;

if (r) {
this_cpu_write(pqr_state.default_closid, r->closid);
- this_cpu_write(pqr_state.default_rmid, r->mon.rmid);
+ this_cpu_write(pqr_state.default_rmid, r->rmid);
}

/*
@@ -376,11 +376,20 @@ static void update_cpu_closid_rmid(void *info)
* Update the PGR_ASSOC MSR on all cpus in @cpu_mask,
*
* Per task closids/rmids must have been set up before calling this function.
+ * @r may be NULL.
*/
static void
update_closid_rmid(const struct cpumask *cpu_mask, struct rdtgroup *r)
{
- on_each_cpu_mask(cpu_mask, update_cpu_closid_rmid, r, 1);
+ struct resctrl_cpu_defaults defaults, *p = NULL;
+
+ if (r) {
+ defaults.closid = r->closid;
+ defaults.rmid = r->mon.rmid;
+ p = &defaults;
+ }
+
+ on_each_cpu_mask(cpu_mask, resctrl_arch_sync_cpu_closid_rmid, p, 1);
}

static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index d16dc960f1fc..31808b3ddecb 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -266,6 +266,28 @@ struct resctrl_schema {
u32 num_closid;
};

+struct resctrl_cpu_defaults {
+ u32 closid;
+ u32 rmid;
+};
+
+/**
+ * resctrl_arch_sync_cpu_closid_rmid() - Refresh this CPU's CLOSID and RMID.
+ * Call via IPI.
+ * @info: If non-NULL, a pointer to a struct resctrl_cpu_defaults
+ * specifying the new CLOSID and RMID for tasks in the default
+ * resctrl ctrl and mon group when running on this CPU. If NULL,
+ * this CPU is not re-assigned to a different default group.
+ *
+ * Propagates reassignment of CPUs and/or tasks to different resctrl groups
+ * when requested by the resctrl core code.
+ *
+ * This function records the per-cpu defaults specified by @info (if any),
+ * and then reconfigures the CPU's hardware CLOSID and RMID for subsequent
+ * execution based on @current, in the same way as during a task switch.
+ */
+void resctrl_arch_sync_cpu_closid_rmid(void *info);
+
/**
* resctrl_get_default_ctrl() - Return the default control value for this
* resource.
--
2.39.5