linux-kernel - [PATCH v2 05/35] x86/resctrl: Remove rdtgroup from update_cpu_closid

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Date: Fri, 26 Apr 2024 16:08:34 +0100
From: Dave Martin <Dave.Martin@....com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: James Morse <james.morse@....com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	H Peter Anvin <hpa@...or.com>,
	Babu Moger <Babu.Moger@....com>,
	shameerali.kolothum.thodi@...wei.com,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com,
	lcherian@...vell.com,
	bobo.shaobowang@...wei.com,
	"Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
	baolin.wang@...ux.alibaba.com,
	Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>,
	Peter Newman <peternewman@...gle.com>,
	dfustini@...libre.com,
	amitsinght@...vell.com,
	David Hildenbrand <david@...hat.com>,
	Rex Nie <rex.nie@...uarmicro.com>
Subject: [PATCH v2 05/35] x86/resctrl: Remove rdtgroup from update_cpu_closid_rmid()

From: James Morse <james.morse@....com>

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.

Signed-off-by: James Morse <james.morse@....com>
Signed-off-by: Dave Martin <Dave.Martin@....com>

---

Changes in v2:

 * 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 98c051ac848d..871b59c2c886 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -341,13 +341,13 @@ 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);
 	}
 
 	/*
@@ -362,11 +362,20 @@ 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 6e87bc95f5ea..bf736ec22f71 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -220,6 +220,28 @@ 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);
+
 /* The number of closid supported by this resource regardless of CDP */
 u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
-- 
2.34.1