x86/resctrl: Add helper for setting CPU default properties

rdtgroup_rmdir_ctrl() and rdtgroup_rmdir_mon() set the per-CPU pqr_state for
CPUs that were part of the rmdir()'d group.

Another architecture might not have a 'pqr_state', its hardware may need the
values in a different format. MPAM's equivalent of RMID values are not unique,
and always need the CLOSID to be provided too.

There is only one caller that modifies a single value, (rdtgroup_rmdir_mon()).
MPAM always needs both CLOSID and RMID for the hardware value as these are
written to the same system register.

As rdtgroup_rmdir_mon() has the CLOSID on hand, only provide a helper to set
both values. These values are read by __resctrl_sched_in(), but may be written
by a different CPU without any locking, add READ/WRTE_ONCE() to avoid torn
values.

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>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
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>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-10-james.morse@arm.com

diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 8b1b6ce1e51b211ba2ce9f786bfa0922bdc6e38b..6908cd0e6e40157c324a5cbdd0e07d932096cf59 100644 (file)
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -4,8 +4,9 @@
 
 #ifdef CONFIG_X86_CPU_RESCTRL
 
-#include <linux/sched.h>
 #include <linux/jump_label.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
 
 /*
  * This value can never be a valid CLOSID, and is used when mapping a
@@ -96,8 +97,8 @@ static inline void resctrl_arch_disable_mon(void)
 static inline void __resctrl_sched_in(struct task_struct *tsk)
 {
        struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
-       u32 closid = state->default_closid;
-       u32 rmid = state->default_rmid;
+       u32 closid = READ_ONCE(state->default_closid);
+       u32 rmid = READ_ONCE(state->default_rmid);
        u32 tmp;
 
        /*
@@ -132,6 +133,13 @@ static inline unsigned int resctrl_arch_round_mon_val(unsigned int val)
        return val * scale;
 }
 
+static inline void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid,
+                                                           u32 rmid)
+{
+       WRITE_ONCE(per_cpu(pqr_state.default_closid, cpu), closid);
+       WRITE_ONCE(per_cpu(pqr_state.default_rmid, cpu), rmid);
+}
+
 static inline void resctrl_arch_set_closid_rmid(struct task_struct *tsk,
                                                u32 closid, u32 rmid)
 {

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index cd8f65c12124b34fcf91c8074855916773da41f8..f706e5a288b15a69e3722d33c96a48a2e980e6cc 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3731,14 +3731,21 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
 static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 {
        struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
+       u32 closid, rmid;
        int cpu;
 
        /* Give any tasks back to the parent group */
        rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
 
-       /* Update per cpu rmid of the moved CPUs first */
+       /*
+        * Update per cpu closid/rmid of the moved CPUs first.
+        * Note: the closid will not change, but the arch code still needs it.
+        */
+       closid = prdtgrp->closid;
+       rmid = prdtgrp->mon.rmid;
        for_each_cpu(cpu, &rdtgrp->cpu_mask)
-               per_cpu(pqr_state.default_rmid, cpu) = prdtgrp->mon.rmid;
+               resctrl_arch_set_cpu_default_closid_rmid(cpu, closid, rmid);
+
        /*
         * Update the MSR on moved CPUs and CPUs which have moved
         * task running on them.
@@ -3771,6 +3778,7 @@ static int rdtgroup_ctrl_remove(struct rdtgroup *rdtgrp)
 
 static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 {
+       u32 closid, rmid;
        int cpu;
 
        /* Give any tasks back to the default group */
@@ -3781,10 +3789,10 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
                   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
 
        /* Update per cpu closid and rmid of the moved CPUs first */
-       for_each_cpu(cpu, &rdtgrp->cpu_mask) {
-               per_cpu(pqr_state.default_closid, cpu) = rdtgroup_default.closid;
-               per_cpu(pqr_state.default_rmid, cpu) = rdtgroup_default.mon.rmid;
-       }
+       closid = rdtgroup_default.closid;
+       rmid = rdtgroup_default.mon.rmid;
+       for_each_cpu(cpu, &rdtgrp->cpu_mask)
+               resctrl_arch_set_cpu_default_closid_rmid(cpu, closid, rmid);
 
        /*
         * Update the MSR on moved CPUs and CPUs which have moved