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From:   James Morse <james.morse@arm.com>
To:     x86@kernel.org, linux-kernel@vger.kernel.org
Cc:     Fenghua Yu <fenghua.yu@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        H Peter Anvin <hpa@zytor.com>,
        Babu Moger <Babu.Moger@amd.com>,
        James Morse <james.morse@arm.com>,
        shameerali.kolothum.thodi@huawei.com,
        Jamie Iles <jamie@nuviainc.com>,
        D Scott Phillips OS <scott@os.amperecomputing.com>,
        lcherian@marvell.com, bobo.shaobowang@huawei.com,
        tan.shaopeng@fujitsu.com
Subject: [PATCH v3 07/21] x86/resctrl: Create mba_sc configuration in the rdt_domain
Date:   Thu, 17 Feb 2022 18:20:56 +0000
Message-Id: <20220217182110.7176-8-james.morse@arm.com>
In-Reply-To: <20220217182110.7176-1-james.morse@arm.com>
References: <20220217182110.7176-1-james.morse@arm.com>
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To support resctrl's MBA software controller, the architecture must provide
a second configuration array to hold the mbps_val[] from user-space.

This complicates the interface between the architecture specific code and
the filesystem portions of resctrl that will move to /fs/, to allow
multiple architectures to support resctrl.

Make the filesystem parts of resctrl create an array for the mba_sc
values when is_mba_sc() is set to true. The software controller
can be changed to use this, allowing the architecture code to only
consider the values configured in hardware.

Signed-off-by: James Morse <james.morse@arm.com>
---
Changes since v2:
 * Split patch in two, the liftime parts are a separate patch.
 * Added reset in set_mba_sc() now that we can't depend on the lifetime.
 * Initialise ret in mba_sc_allocate(),
 * Made mbps_val allocation/freeing symmetric for cpuhp calls.
 * Removed reference to squashed-out struct.
 * Preserved kerneldoc for mbps_val.

Changes since v1:
 * Added missing error handling to mba_sc_domain_allocate() in
   domain_setup_mon_state()
 * Added comment about mba_sc_domain_allocate() races
 * Squashed out struct resctrl_mba_sc
 * Moved mount time alloc/free calls to set_mba_sc().
 * Removed mount check in resctrl_offline_domain()
 * Reword commit message
---
 arch/x86/kernel/cpu/resctrl/internal.h |  1 -
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 41 ++++++++++++++++++++++++++
 include/linux/resctrl.h                |  7 +++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index e12b55f815bf..a7e2cbce29d5 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -36,7 +36,6 @@
 #define MBM_OVERFLOW_INTERVAL		1000
 #define MAX_MBA_BW			100u
 #define MBA_IS_LINEAR			0x4
-#define MBA_MAX_MBPS			U32_MAX
 #define MAX_MBA_BW_AMD			0x800
 #define MBM_CNTR_WIDTH_OFFSET_AMD	20
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 794a84ba9097..e4313f907eb6 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1889,6 +1889,30 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r)
 		l3_qos_cfg_update(&hw_res->cdp_enabled);
 }
 
+static int mba_sc_domain_allocate(struct rdt_resource *r, struct rdt_domain *d)
+{
+	u32 num_closid = resctrl_arch_get_num_closid(r);
+	int cpu = cpumask_any(&d->cpu_mask);
+	int i;
+
+	d->mbps_val = kcalloc_node(num_closid, sizeof(*d->mbps_val),
+				   GFP_KERNEL, cpu_to_node(cpu));
+	if (!d->mbps_val)
+		return -ENOMEM;
+
+	for (i = 0; i < num_closid; i++)
+		d->mbps_val[i] = MBA_MAX_MBPS;
+
+	return 0;
+}
+
+static void mba_sc_domain_destroy(struct rdt_resource *r,
+				  struct rdt_domain *d)
+{
+	kfree(d->mbps_val);
+	d->mbps_val = NULL;
+}
+
 /*
  * Enable or disable the MBA software controller
  * which helps user specify bandwidth in MBps.
@@ -1898,6 +1922,9 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r)
 static int set_mba_sc(bool mba_sc)
 {
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
+	u32 num_closid = resctrl_arch_get_num_closid(r);
+	struct rdt_domain *d;
+	int i;
 
 	if (!is_mbm_enabled() || !is_mba_linear() ||
 	    mba_sc == is_mba_sc(r))
@@ -1905,6 +1932,11 @@ static int set_mba_sc(bool mba_sc)
 
 	r->membw.mba_sc = mba_sc;
 
+	list_for_each_entry(d, &r->domains, list) {
+		for (i = 0; i < num_closid; i++)
+			d->mbps_val[i] = MBA_MAX_MBPS;
+	}
+
 	return 0;
 }
 
@@ -3263,6 +3295,9 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d)
 		cancel_delayed_work(&d->cqm_limbo);
 	}
 
+	if (is_mba_sc(r))
+		mba_sc_domain_destroy(r, d);
+
 	domain_destroy_mon_state(d);
 }
 
@@ -3309,6 +3344,12 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d)
 	if (err)
 		return err;
 
+	err = mba_sc_domain_allocate(r, d);
+	if (err) {
+		domain_destroy_mon_state(d);
+		return err;
+	}
+
 	if (is_mbm_enabled()) {
 		INIT_DELAYED_WORK(&d->mbm_over, mbm_handle_overflow);
 		mbm_setup_overflow_handler(d, MBM_OVERFLOW_INTERVAL);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 5d283bdd6162..46ab9fb5562e 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -15,6 +15,9 @@ int proc_resctrl_show(struct seq_file *m,
 
 #endif
 
+/* max value for struct rdt_domain's mbps_val */
+#define MBA_MAX_MBPS   U32_MAX
+
 /**
  * enum resctrl_conf_type - The type of configuration.
  * @CDP_NONE:	No prioritisation, both code and data are controlled or monitored.
@@ -53,6 +56,9 @@ struct resctrl_staged_config {
  * @cqm_work_cpu:	worker CPU for CQM h/w counters
  * @plr:		pseudo-locked region (if any) associated with domain
  * @staged_config:	parsed configuration to be applied
+ * @mbps_val:		When mba_sc is enabled, this holds the array of user
+ * 			specified control values for mba_sc in MBps, indexed
+ *			by closid
  */
 struct rdt_domain {
 	struct list_head		list;
@@ -67,6 +73,7 @@ struct rdt_domain {
 	int				cqm_work_cpu;
 	struct pseudo_lock_region	*plr;
 	struct resctrl_staged_config	staged_config[CDP_NUM_TYPES];
+	u32				*mbps_val;
 };
 
 /**
-- 
2.30.2