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Date: Mon, 25 Mar 2024 10:27:06 -0700
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Subject: [PATCH v1 5/6] x86/resctrl: Abstract PQR_ASSOC from generic code
From: Peter Newman <peternewman@google.com>
To: Fenghua Yu <fenghua.yu@intel.com>, Reinette Chatre <reinette.chatre@intel.com>, 
	James Morse <james.morse@arm.com>
Cc: Stephane Eranian <eranian@google.com>, Thomas Gleixner <tglx@linutronix.de>, 
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, 
	Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org, 
	"H. Peter Anvin" <hpa@zytor.com>, Peter Zijlstra <peterz@infradead.org>, Juri Lelli <juri.lelli@redhat.com>, 
	Vincent Guittot <vincent.guittot@linaro.org>, Dietmar Eggemann <dietmar.eggemann@arm.com>, 
	Steven Rostedt <rostedt@goodmis.org>, Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>, 
	Daniel Bristot de Oliveira <bristot@redhat.com>, Valentin Schneider <vschneid@redhat.com>, 
	Uros Bizjak <ubizjak@gmail.com>, Mike Rapoport <rppt@kernel.org>, 
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, 
	Rick Edgecombe <rick.p.edgecombe@intel.com>, Xin Li <xin3.li@intel.com>, 
	Babu Moger <babu.moger@amd.com>, Shaopeng Tan <tan.shaopeng@fujitsu.com>, 
	Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>, Jens Axboe <axboe@kernel.dk>, 
	Christian Brauner <brauner@kernel.org>, Oleg Nesterov <oleg@redhat.com>, 
	Andrew Morton <akpm@linux-foundation.org>, Tycho Andersen <tandersen@netflix.com>, 
	Nicholas Piggin <npiggin@gmail.com>, Beau Belgrave <beaub@linux.microsoft.com>, 
	"Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-kernel@vger.kernel.org, 
	Peter Newman <peternewman@google.com>
Content-Type: text/plain; charset="UTF-8"

While CLOSID and RMID originated in RDT, the concept applies to other
architectures, as it's standard to write allocation and monitoring IDs
into per-CPU registers.

 - Rename resctrl_pqr_state and pqr_state to be more
   architecturally-neutral.

 - Introduce resctrl_arch_update_cpu() to replace the explicit write to
   MSR_IA32_PQR_ASSOC in __resctrl_sched_in(). In the case of MPAM,
   PARTID[_I,D] and PMG are a simple function of closid, rmid, and an
   internal global.

 - Update terminology containing explicit references to the PQR_ASSOC
   register.

Signed-off-by: Peter Newman <peternewman@google.com>
---
 arch/x86/kernel/cpu/resctrl/core.c        | 11 ++++++++---
 arch/x86/kernel/cpu/resctrl/internal.h    |  6 +++---
 arch/x86/kernel/cpu/resctrl/pseudo_lock.c |  4 ++--
 arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 18 +++++++++---------
 include/linux/resctrl.h                   | 11 +++++++++++
 5 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index ae5878d748fc..4cc584754f8b 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -37,12 +37,12 @@
 static DEFINE_MUTEX(domain_list_lock);
 
 /*
- * The cached resctrl_pqr_state is strictly per CPU and can never be
+ * The cached resctrl_cpu_state is strictly per CPU and can never be
  * updated from a remote CPU. Functions which modify the state
  * are called with interrupts disabled and no preemption, which
  * is sufficient for the protection.
  */
-DEFINE_PER_CPU(struct resctrl_pqr_state, pqr_state);
+DEFINE_PER_CPU(struct resctrl_cpu_state, resctrl_state);
 
 /*
  * Used to store the max resource name width and max resource data width
@@ -309,6 +309,11 @@ static void rdt_get_cdp_l2_config(void)
 	rdt_get_cdp_config(RDT_RESOURCE_L2);
 }
 
+void resctrl_arch_update_cpu(u32 ctrl_id, u32 mon_id)
+{
+	wrmsr(MSR_IA32_PQR_ASSOC, mon_id, ctrl_id);
+}
+
 static void
 mba_wrmsr_amd(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
 {
@@ -598,7 +603,7 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 
 static void clear_closid_rmid(int cpu)
 {
-	struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
+	struct resctrl_cpu_state *state = this_cpu_ptr(&resctrl_state);
 
 	state->default_group = &rdtgroup_default;
 	state->cur_closid = RESCTRL_RESERVED_CLOSID;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 0ba0d2428780..e30f42744ac7 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -332,7 +332,7 @@ struct rftype {
 };
 
 /**
- * struct resctrl_pqr_state - State cache for the PQR MSR
+ * struct resctrl_cpu_state - State cache for allocation/monitoring group IDs
  * @cur_rmid:		The cached Resource Monitoring ID
  * @cur_closid:		The cached Class Of Service ID
  * @default_group:	The user assigned rdtgroup
@@ -340,13 +340,13 @@ struct rftype {
  * The cache also helps to avoid pointless updates if the value does
  * not change.
  */
-struct resctrl_pqr_state {
+struct resctrl_cpu_state {
 	u32			cur_rmid;
 	u32			cur_closid;
 	struct rdtgroup		*default_group;
 };
 
-DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
+DECLARE_PER_CPU(struct resctrl_cpu_state, resctrl_state);
 
 /**
  * struct mbm_state - status for each MBM counter in each domain
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
index 884b88e25141..ca1805a566cb 100644
--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
+++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -480,8 +480,8 @@ static int pseudo_lock_fn(void *_rdtgrp)
 	 */
 	saved_msr = __rdmsr(MSR_MISC_FEATURE_CONTROL);
 	__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
-	closid_p = this_cpu_read(pqr_state.cur_closid);
-	rmid_p = this_cpu_read(pqr_state.cur_rmid);
+	closid_p = this_cpu_read(resctrl_state.cur_closid);
+	rmid_p = this_cpu_read(resctrl_state.cur_rmid);
 	mem_r = plr->kmem;
 	size = plr->size;
 	line_size = plr->line_size;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index badf181c8cbb..bd067f7ed5b6 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -112,7 +112,7 @@ void rdt_staged_configs_clear(void)
  * + We can simply set current's closid to assign a task to a resource
  *   group.
  * + Context switch code can avoid extra memory references deciding which
- *   CLOSID to load into the PQR_ASSOC MSR
+ *   CLOSID to load into the CPU
  * - We give up some options in configuring resource groups across multi-socket
  *   systems.
  * - Our choices on how to configure each resource become progressively more
@@ -347,7 +347,7 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
  */
 void __resctrl_sched_in(struct task_struct *tsk)
 {
-	struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
+	struct resctrl_cpu_state *state = this_cpu_ptr(&resctrl_state);
 	u32 closid = state->cur_closid;
 	u32 rmid = state->cur_rmid;
 	struct rdtgroup *rgrp;
@@ -401,7 +401,7 @@ void __resctrl_sched_in(struct task_struct *tsk)
 	if (closid != state->cur_closid || rmid != state->cur_rmid) {
 		state->cur_closid = closid;
 		state->cur_rmid = rmid;
-		wrmsr(MSR_IA32_PQR_ASSOC, rmid, closid);
+		resctrl_arch_update_cpu(closid, rmid);
 	}
 }
 
@@ -416,7 +416,7 @@ static void update_cpu_closid_rmid(void *info)
 	struct rdtgroup *r = info;
 
 	if (r)
-		this_cpu_write(pqr_state.default_group, r);
+		this_cpu_write(resctrl_state.default_group, r);
 
 	/*
 	 * We cannot unconditionally write the MSR because the current
@@ -635,8 +635,8 @@ static void rdtgroup_remove(struct rdtgroup *rdtgrp)
 static void _update_task_closid_rmid(void *task)
 {
 	/*
-	 * If the task is still current on this CPU, update PQR_ASSOC MSR.
-	 * Otherwise, the MSR is updated when the task is scheduled in.
+	 * If the task is still current on this CPU, update the current ctrl
+	 * group. Otherwise, the CPU is updated when the task is scheduled in.
 	 */
 	if (task == current)
 		resctrl_sched_in(task);
@@ -3005,7 +3005,7 @@ static void rmdir_all_sub(void)
 		else
 			rdtgroup_remove(rdtgrp);
 	}
-	/* Notify online CPUs to update per cpu storage and PQR_ASSOC MSR */
+	/* Update online CPUs to propagate group membership changes. */
 	update_closid_rmid(cpu_online_mask, &rdtgroup_default);
 
 	kernfs_remove(kn_info);
@@ -3688,7 +3688,7 @@ static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 
 	/* Update per cpu rmid of the moved CPUs first */
 	for_each_cpu(cpu, &rdtgrp->cpu_mask)
-		per_cpu(pqr_state.default_group, cpu) = prdtgrp;
+		per_cpu(resctrl_state.default_group, cpu) = prdtgrp;
 	/*
 	 * Update the MSR on moved CPUs and CPUs which have moved
 	 * task running on them.
@@ -3732,7 +3732,7 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 
 	/* Update per cpu closid and rmid of the moved CPUs first */
 	for_each_cpu(cpu, &rdtgrp->cpu_mask)
-		per_cpu(pqr_state.default_group, cpu) = &rdtgroup_default;
+		per_cpu(resctrl_state.default_group, cpu) = &rdtgroup_default;
 
 	/*
 	 * Update the MSR on moved CPUs and CPUs which have moved
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index b2af1fbc7aa1..a6b1b13cc769 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -306,6 +306,17 @@ extern unsigned int resctrl_rmid_realloc_limit;
 
 DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
 
+/*
+ * resctrl_arch_update_cpu() - Make control and monitoring group IDs effective
+ *			       on the current CPU
+ *
+ * @ctrl_id:	An identifier for the control group which is to be used on the
+ *		current CPU.
+ * @mon_id:	An identifier for the monitoring group which is to be used on
+ *		the current CPU.
+ */
+void resctrl_arch_update_cpu(u32 ctrl_id, u32 mon_id);
+
 void __resctrl_sched_in(struct task_struct *tsk);
 
 /*
-- 
2.44.0.396.g6e790dbe36-goog