linux-kernel - [PATCH v6 14/42] x86/resctrl: Add an arch helper to reset one resource

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Message-Id: <20250207181823.6378-15-james.morse@arm.com>
Date: Fri,  7 Feb 2025 18:17:55 +0000
From: James Morse <james.morse@....com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: 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>,
	James Morse <james.morse@....com>,
	shameerali.kolothum.thodi@...wei.com,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com,
	lcherian@...vell.com,
	bobo.shaobowang@...wei.com,
	tan.shaopeng@...itsu.com,
	baolin.wang@...ux.alibaba.com,
	Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>,
	peternewman@...gle.com,
	dfustini@...libre.com,
	amitsinght@...vell.com,
	David Hildenbrand <david@...hat.com>,
	Rex Nie <rex.nie@...uarmicro.com>,
	Dave Martin <dave.martin@....com>,
	Koba Ko <kobak@...dia.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v6 14/42] x86/resctrl: Add an arch helper to reset one resource

On umount(), resctrl resets each resource back to its default
configuration. It only ever does this for all resources in one go.

reset_all_ctrls() is architecture specific as it works with struct
rdt_hw_resource.

Make reset_all_ctrls() an arch helper that resets one resource.

Signed-off-by: James Morse <james.morse@....com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
Changes since v5:
 * Move the arch/fs split into the for-each loop at Reinette's suggestion.
 * Dropped a bunch of tags and rewrote the commit message.

Changes since v1:
 * Rename the for_each_capable_rdt_resource() introduced in the new
   function resctrl_arch_reset_resources(), back to
   for_each_alloc_capable_rdt_resource() as it was in the original code.

   The change looked unintentional; and presumably a resource that does
   not support resource allocation doesn't have any properties to
   reset...
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 9 +++++----
 include/linux/resctrl.h                | 9 +++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index b2dad689e780..9eb57ebb36c6 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2867,7 +2867,7 @@ static int rdt_init_fs_context(struct fs_context *fc)
 	return 0;
 }
 
-static int reset_all_ctrls(struct rdt_resource *r)
+void resctrl_arch_reset_all_ctrls(struct rdt_resource *r)
 {
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 	struct rdt_hw_ctrl_domain *hw_dom;
@@ -2896,7 +2896,7 @@ static int reset_all_ctrls(struct rdt_resource *r)
 		smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &msr_param, 1);
 	}
 
-	return 0;
+	return;
 }
 
 /*
@@ -3015,9 +3015,10 @@ static void rdt_kill_sb(struct super_block *sb)
 
 	rdt_disable_ctx();
 
-	/*Put everything back to default values. */
+	/* Put everything back to default values. */
 	for_each_alloc_capable_rdt_resource(r)
-		reset_all_ctrls(r);
+		resctrl_arch_reset_all_ctrls(r);
+
 	rmdir_all_sub();
 	rdt_pseudo_lock_release();
 	rdtgroup_default.mode = RDT_MODE_SHAREABLE;
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 74cfd48e69ee..4444bc05e39c 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -414,6 +414,15 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_mon_domain *d,
  */
 void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *d);
 
+/**
+ * resctrl_arch_reset_all_ctrls() - Reset the control for each CLOSID to its
+ *				    default.
+ * @r:		The resctrl resource to reset.
+ *
+ * This can be called from any CPU.
+ */
+void resctrl_arch_reset_all_ctrls(struct rdt_resource *r);
+
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 
-- 
2.39.2