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Date: Fri, 1 Oct 2021 16:02:47 +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,
Jamie Iles <jamie@...iainc.com>,
D Scott Phillips OS <scott@...amperecomputing.com>,
lcherian@...vell.com, bobo.shaobowang@...wei.com,
tan.shaopeng@...itsu.com
Subject: [PATCH v2 08/23] x86/resctrl: Create mba_sc configuration in the rdt_domain
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 code.
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@....com>
---
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 | 67 ++++++++++++++++++++++++++
include/linux/resctrl.h | 6 +++
3 files changed, 73 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 38670bb810cb..9d402bc8bdff 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1889,6 +1889,64 @@ 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 is allocated by a call to this function in set_mba_sc(),
+ * and domain_setup_mon_state(). Both calls are guarded by is_mba_sc(),
+ * which can only return true while the filesystem is mounted. The
+ * two calls are prevented from racing as rdt_get_tree() takes the
+ * cpuhp read lock before calling rdt_enable_ctx(ctx), which prevents
+ * it running concurrently with resctrl_online_domain().
+ */
+ lockdep_assert_cpus_held();
+
+ 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 int mba_sc_allocate(struct rdt_resource *r)
+{
+ struct rdt_domain *d;
+ int ret;
+
+ list_for_each_entry(d, &r->domains, list) {
+ ret = mba_sc_domain_allocate(r, d);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+static void mba_sc_domain_destroy(struct rdt_resource *r,
+ struct rdt_domain *d)
+{
+ kfree(d->mbps_val);
+ d->mbps_val = NULL;
+}
+
+static void mba_sc_destroy(struct rdt_resource *r)
+{
+ struct rdt_domain *d;
+
+ lockdep_assert_cpus_held();
+
+ list_for_each_entry(d, &r->domains, list)
+ mba_sc_domain_destroy(r, d);
+}
+
/*
* Enable or disable the MBA software controller
* which helps user specify bandwidth in MBps.
@@ -1911,6 +1969,10 @@ static int set_mba_sc(bool mba_sc)
setup_default_ctrlval(r, hw_dom->ctrl_val, hw_dom->mbps_val);
}
+ if (is_mba_sc(r))
+ return mba_sc_allocate(r);
+
+ mba_sc_destroy(r);
return 0;
}
@@ -3259,6 +3321,8 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d)
__check_limbo(d, true);
cancel_delayed_work(&d->cqm_limbo);
}
+ if (is_mba_sc(r))
+ mba_sc_domain_destroy(r, d);
bitmap_free(d->rmid_busy_llc);
kfree(d->mbm_total);
kfree(d->mbm_local);
@@ -3291,6 +3355,9 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_domain *d)
}
}
+ if (is_mba_sc(r))
+ return mba_sc_domain_allocate(r, d);
+
return 0;
}
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 5d283bdd6162..355660d46612 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 resctrl_mba_sc'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 +56,8 @@ 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: Array of user specified control values for mba_sc,
+ * indexed by closid
*/
struct rdt_domain {
struct list_head list;
@@ -67,6 +72,7 @@ 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
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