linux-kernel - [PATCH v6 20/24] x86/resctrl: Add CPU online callback for resctrl work

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Message-Id: <20230914172138.11977-21-james.morse@arm.com>
Date:   Thu, 14 Sep 2023 17:21:34 +0000
From:   James Morse <james.morse@....com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     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>,
        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,
        xingxin.hx@...nanolis.org, 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
Subject: [PATCH v6 20/24] x86/resctrl: Add CPU online callback for resctrl work

The resctrl architecture specific code may need to create a domain when
a CPU comes online, it also needs to reset the CPUs PQR_ASSOC register.
The resctrl filesystem code needs to update the rdtgroup_default CPU
mask when CPUs are brought online.

Currently this is all done in one function, resctrl_online_cpu().
This will need to be split into architecture and filesystem parts
before resctrl can be moved to /fs/.

Pull the rdtgroup_default update work out as a filesystem specific
cpu_online helper. resctrl_online_cpu() is the obvious name for this,
which means the version in core.c needs renaming.

resctrl_online_cpu() is called by the arch code once it has done the
work to add the new CPU to any domains.

In future patches, resctrl_online_cpu() will take the rdtgroup_mutex
itself.

Reviewed-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
Tested-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
Tested-By: Peter Newman <peternewman@...gle.com>
Signed-off-by: James Morse <james.morse@....com>
---
Changes since v3:
 * Renamed err to ret

Changes since v4:
 * Changes in capitalisation.

Changes since v5:
 * More changes in capitalisation.
 * Made resctrl_online_cpu() return void.
---
 arch/x86/kernel/cpu/resctrl/core.c     | 8 ++++----
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 8 ++++++++
 include/linux/resctrl.h                | 1 +
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index eaadf6f20900..5b4c719ac129 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -604,16 +604,16 @@ static void clear_closid_rmid(int cpu)
 	      RESCTRL_RESERVED_CLOSID);
 }
 
-static int resctrl_online_cpu(unsigned int cpu)
+static int resctrl_arch_online_cpu(unsigned int cpu)
 {
 	struct rdt_resource *r;
 
 	mutex_lock(&rdtgroup_mutex);
 	for_each_capable_rdt_resource(r)
 		domain_add_cpu(cpu, r);
-	/* The cpu is set in default rdtgroup after online. */
-	cpumask_set_cpu(cpu, &rdtgroup_default.cpu_mask);
 	clear_closid_rmid(cpu);
+
+	resctrl_online_cpu(cpu);
 	mutex_unlock(&rdtgroup_mutex);
 
 	return 0;
@@ -966,7 +966,7 @@ static int __init resctrl_late_init(void)
 
 	state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
 				  "x86/resctrl/cat:online:",
-				  resctrl_online_cpu, resctrl_offline_cpu);
+				  resctrl_arch_online_cpu, resctrl_offline_cpu);
 	if (state < 0)
 		return state;
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index dfaef047dead..0c609cdfe7e5 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3868,6 +3868,14 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d)
 	return 0;
 }
 
+void resctrl_online_cpu(unsigned int cpu)
+{
+	lockdep_assert_held(&rdtgroup_mutex);
+
+	/* The CPU is set in default rdtgroup after online. */
+	cpumask_set_cpu(cpu, &rdtgroup_default.cpu_mask);
+}
+
 /*
  * rdtgroup_init - rdtgroup initialization
  *
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 5e4b4df9610b..9d5f75a4e192 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -223,6 +223,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d,
 			    u32 closid, enum resctrl_conf_type type);
 int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d);
 void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);
+void resctrl_online_cpu(unsigned int cpu);
 
 /**
  * resctrl_arch_rmid_read() - Read the eventid counter corresponding to rmid
-- 
2.39.2