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Date: Thu, 6 Aug 2015 14:55:16 -0700
From: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
To: vikas.shivappa@...el.com
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com,
tglx@...utronix.de, mingo@...nel.org, tj@...nel.org,
peterz@...radead.org, matt.fleming@...el.com, will.auld@...el.com,
glenn.p.williamson@...el.com, kanaka.d.juvva@...el.com,
vikas.shivappa@...ux.intel.com
Subject: [PATCH 8/9] x86/intel_rdt: Hot cpu support for Cache Allocation
This patch adds hot cpu support for Intel Cache allocation. Support
includes updating the cache bitmask MSRs IA32_L3_QOS_n when a new CPU
package comes online. The IA32_L3_QOS_n MSRs are one per Class of
service on each CPU package. The new package's MSRs are synchronized
with the values of existing MSRs. Also the software cache for
IA32_PQR_ASSOC MSRs are reset during hot cpu notifications.
Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
---
arch/x86/kernel/cpu/intel_rdt.c | 95 ++++++++++++++++++++++++++++++++++++++---
1 file changed, 90 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 06cba8da..f151200 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -25,6 +25,7 @@
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/spinlock.h>
+#include <linux/cpu.h>
#include <asm/intel_rdt.h>
/*
@@ -40,6 +41,11 @@ struct static_key __read_mostly rdt_enable_key = STATIC_KEY_INIT_FALSE;
* Mask of CPUs for writing CBM values. We only need one CPU per-socket.
*/
static cpumask_t rdt_cpumask;
+/*
+ * Temporary cpumask used during hot cpu notificaiton handling. The usage
+ * is serialized by hot cpu locks.
+ */
+static cpumask_t tmp_cpumask;
#define rdt_for_each_child(pos_css, parent_ir) \
css_for_each_child((pos_css), &(parent_ir)->css)
@@ -311,13 +317,86 @@ out:
return err;
}
-static inline void rdt_cpumask_update(int cpu)
+static inline bool rdt_cpumask_update(int cpu)
{
- static cpumask_t tmp;
-
- cpumask_and(&tmp, &rdt_cpumask, topology_core_cpumask(cpu));
- if (cpumask_empty(&tmp))
+ cpumask_and(&tmp_cpumask, &rdt_cpumask, topology_core_cpumask(cpu));
+ if (cpumask_empty(&tmp_cpumask)) {
cpumask_set_cpu(cpu, &rdt_cpumask);
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * cbm_update_msrs() - Updates all the existing IA32_L3_MASK_n MSRs
+ * which are one per CLOSid except IA32_L3_MASK_0 on the current package.
+ */
+static void cbm_update_msrs(void *info)
+{
+ int maxid = boot_cpu_data.x86_cache_max_closid;
+ unsigned int i;
+
+ /*
+ * At cpureset, all bits of IA32_L3_MASK_n are set.
+ * The index starts from one as there is no need
+ * to update IA32_L3_MASK_0 as it belongs to root cgroup
+ * whose cache mask is all 1s always.
+ */
+ for (i = 1; i < maxid; i++) {
+ if (cctable[i].clos_refcnt)
+ cbm_cpu_update((void *)i);
+ }
+}
+
+static inline void intel_rdt_cpu_start(int cpu)
+{
+ struct intel_pqr_state *state = &per_cpu(pqr_state, cpu);
+
+ state->closid = 0;
+ mutex_lock(&rdt_group_mutex);
+ if (rdt_cpumask_update(cpu))
+ smp_call_function_single(cpu, cbm_update_msrs, NULL, 1);
+ mutex_unlock(&rdt_group_mutex);
+}
+
+static void intel_rdt_cpu_exit(unsigned int cpu)
+{
+ int i;
+
+ mutex_lock(&rdt_group_mutex);
+ if (!cpumask_test_and_clear_cpu(cpu, &rdt_cpumask)) {
+ mutex_unlock(&rdt_group_mutex);
+ return;
+ }
+
+ cpumask_and(&tmp_cpumask, topology_core_cpumask(cpu), cpu_online_mask);
+ cpumask_clear_cpu(cpu, &tmp_cpumask);
+ i = cpumask_any(&tmp_cpumask);
+
+ if (i < nr_cpu_ids)
+ cpumask_set_cpu(i, &rdt_cpumask);
+ mutex_unlock(&rdt_group_mutex);
+}
+
+static int intel_rdt_cpu_notifier(struct notifier_block *nb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+
+ switch (action) {
+ case CPU_DOWN_FAILED:
+ case CPU_ONLINE:
+ intel_rdt_cpu_start(cpu);
+ break;
+ case CPU_DOWN_PREPARE:
+ intel_rdt_cpu_exit(cpu);
+ break;
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
}
static int __init intel_rdt_late_init(void)
@@ -355,9 +434,15 @@ static int __init intel_rdt_late_init(void)
cct->l3_cbm = (1ULL << max_cbm_len) - 1;
cct->clos_refcnt = 1;
+ cpu_notifier_register_begin();
+
for_each_online_cpu(i)
rdt_cpumask_update(i);
+ __hotcpu_notifier(intel_rdt_cpu_notifier, 0);
+
+ cpu_notifier_register_done();
+
static_key_slow_inc(&rdt_enable_key);
pr_info("Intel cache allocation enabled\n");
out_err:
--
1.9.1
--
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