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Subject[PATCH 2/2] sparc64: Use cpu_poke to resume idle cpu
Date
Use cpu_poke hypervisor call to resume idle cpu if supported.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
arch/sparc/include/asm/smp_64.h | 5 ++
arch/sparc/kernel/hvapi.c | 2 +-
arch/sparc/kernel/process_64.c | 7 +++-
arch/sparc/kernel/setup_64.c | 1 +
arch/sparc/kernel/smp_64.c | 80 +++++++++++++++++++++++++++++++++++++-
5 files changed, 90 insertions(+), 5 deletions(-)

diff --git a/arch/sparc/include/asm/smp_64.h b/arch/sparc/include/asm/smp_64.h
index ce2233f..a750892 100644
--- a/arch/sparc/include/asm/smp_64.h
+++ b/arch/sparc/include/asm/smp_64.h
@@ -33,6 +33,9 @@
DECLARE_PER_CPU(cpumask_t, cpu_sibling_map);
extern cpumask_t cpu_core_map[NR_CPUS];

+void smp_init_cpu_poke(void);
+void scheduler_poke(void);
+
void arch_send_call_function_single_ipi(int cpu);
void arch_send_call_function_ipi_mask(const struct cpumask *mask);

@@ -74,6 +77,8 @@
#define smp_fetch_global_regs() do { } while (0)
#define smp_fetch_global_pmu() do { } while (0)
#define smp_fill_in_cpu_possible_map() do { } while (0)
+#define smp_init_cpu_poke() do { } while (0)
+#define scheduler_poke() do { } while (0)

#endif /* !(CONFIG_SMP) */

diff --git a/arch/sparc/kernel/hvapi.c b/arch/sparc/kernel/hvapi.c
index 2677312..0b070d5 100644
--- a/arch/sparc/kernel/hvapi.c
+++ b/arch/sparc/kernel/hvapi.c
@@ -189,7 +189,7 @@ void __init sun4v_hvapi_init(void)

group = HV_GRP_CORE;
major = 1;
- minor = 1;
+ minor = 6; /* CPU POKE */
if (sun4v_hvapi_register(group, major, &minor))
goto bad;

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 1badc49..92448af 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -77,8 +77,13 @@ void arch_cpu_idle(void)
: "=&r" (pstate)
: "i" (PSTATE_IE));

- if (!need_resched() && !cpu_is_offline(smp_processor_id()))
+ if (!need_resched() && !cpu_is_offline(smp_processor_id())) {
sun4v_cpu_yield();
+ /* If resumed by cpu_poke then we need to explicitly
+ * call scheduler_ipi().
+ */
+ scheduler_poke();
+ }

/* Re-enable interrupts. */
__asm__ __volatile__(
diff --git a/arch/sparc/kernel/setup_64.c b/arch/sparc/kernel/setup_64.c
index 422b178..4ff9fd8 100644
--- a/arch/sparc/kernel/setup_64.c
+++ b/arch/sparc/kernel/setup_64.c
@@ -356,6 +356,7 @@ void __init start_early_boot(void)
check_if_starfire();
per_cpu_patch();
sun4v_patch();
+ smp_init_cpu_poke();

cpu = hard_smp_processor_id();
if (cpu >= NR_CPUS) {
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index fdf3104..9c3131b 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -74,6 +74,9 @@

static cpumask_t smp_commenced_mask;

+static DEFINE_PER_CPU(bool, poke);
+static bool cpu_poke;
+
void smp_info(struct seq_file *m)
{
int i;
@@ -1394,15 +1397,86 @@ void __init smp_cpus_done(unsigned int max_cpus)
{
}

+static void send_cpu_ipi(int cpu)
+{
+ xcall_deliver((u64) &xcall_receive_signal,
+ 0, 0, cpumask_of(cpu));
+}
+
+void scheduler_poke(void)
+{
+ if (!cpu_poke)
+ return;
+
+ if (!__this_cpu_read(poke))
+ return;
+
+ __this_cpu_write(poke, false);
+ set_softint(1 << PIL_SMP_RECEIVE_SIGNAL);
+}
+
+static unsigned long send_cpu_poke(int cpu)
+{
+ unsigned long hv_err;
+
+ per_cpu(poke, cpu) = true;
+ hv_err = sun4v_cpu_poke(cpu);
+ if (hv_err != HV_EOK) {
+ per_cpu(poke, cpu) = false;
+ pr_err_ratelimited("%s: sun4v_cpu_poke() fails err=%lu\n",
+ __func__, hv_err);
+ }
+
+ return hv_err;
+}
+
void smp_send_reschedule(int cpu)
{
if (cpu == smp_processor_id()) {
WARN_ON_ONCE(preemptible());
set_softint(1 << PIL_SMP_RECEIVE_SIGNAL);
- } else {
- xcall_deliver((u64) &xcall_receive_signal,
- 0, 0, cpumask_of(cpu));
+ return;
+ }
+
+ /* Use cpu poke to resume idle cpu if supported*/
+ if (cpu_poke && idle_cpu(cpu)) {
+ unsigned long ret;
+
+ ret = send_cpu_poke(cpu);
+ if (ret == HV_EOK)
+ return;
}
+
+ /* Use IPI in following cases:
+ * - cpu poke not supported
+ * - cpu not idle
+ * - send_cpu_poke() returns with error.
+ */
+ send_cpu_ipi(cpu);
+}
+
+void smp_init_cpu_poke(void)
+{
+ unsigned long major;
+ unsigned long minor;
+ int ret;
+
+ if (tlb_type != hypervisor)
+ return;
+
+ ret = sun4v_hvapi_get(HV_GRP_CORE, &major, &minor);
+ if (ret) {
+ pr_debug("HV_GRP_CORE is not registered\n");
+ return;
+ }
+
+ if (major == 1 && minor >= 6) {
+ /*cpu poke is registered. */
+ cpu_poke = true;
+ return;
+ }
+
+ pr_debug("CPU_POKE not supported\n");
}

void __irq_entry smp_receive_signal_client(int irq, struct pt_regs *regs)
--
1.7.1
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