[RFC PATCH v2 26/31] kvx: Add multi-processor (SMP) support
Yann Sionneau
ysionneau at kalray.eu
Fri Jan 20 06:09:57 PST 2023
Coolidge v1 SoC has 5 clusters of 17 kvx cores:
- 16 application cores aka PE
- 1 privileged core, the Resource Manager, aka RM.
Linux can run in SMP config on the 16 cores of a Cluster.
Memory coherency between all cores is guarenteed by the L2 cache.
Co-developed-by: Clement Leger <clement at clement-leger.fr>
Signed-off-by: Clement Leger <clement at clement-leger.fr>
Co-developed-by: Julian Vetter <jvetter at kalray.eu>
Signed-off-by: Julian Vetter <jvetter at kalray.eu>
Co-developed-by: Julien Hascoet <jhascoet at kalray.eu>
Signed-off-by: Julien Hascoet <jhascoet at kalray.eu>
Co-developed-by: Louis Morhet <lmorhet at kalray.eu>
Signed-off-by: Louis Morhet <lmorhet at kalray.eu>
Co-developed-by: Luc Michel <lmichel at kalray.eu>
Signed-off-by: Luc Michel <lmichel at kalray.eu>
Co-developed-by: Marius Gligor <mgligor at kalray.eu>
Signed-off-by: Marius Gligor <mgligor at kalray.eu>
Co-developed-by: Yann Sionneau <ysionneau at kalray.eu>
Signed-off-by: Yann Sionneau <ysionneau at kalray.eu>
---
Notes:
V1 -> V2:
- removed L2 cache driver
- removed ipi and pwr-ctrl driver (splitted in their own patch)
arch/kvx/include/asm/smp.h | 42 ++++++++++++
arch/kvx/kernel/smp.c | 110 ++++++++++++++++++++++++++++++++
arch/kvx/kernel/smpboot.c | 127 +++++++++++++++++++++++++++++++++++++
include/linux/cpuhotplug.h | 2 +
4 files changed, 281 insertions(+)
create mode 100644 arch/kvx/include/asm/smp.h
create mode 100644 arch/kvx/kernel/smp.c
create mode 100644 arch/kvx/kernel/smpboot.c
diff --git a/arch/kvx/include/asm/smp.h b/arch/kvx/include/asm/smp.h
new file mode 100644
index 000000000000..e4fd4d001b2c
--- /dev/null
+++ b/arch/kvx/include/asm/smp.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ */
+
+#ifndef _ASM_KVX_SMP_H
+#define _ASM_KVX_SMP_H
+
+#include <linux/cpumask.h>
+#include <linux/irqreturn.h>
+
+#include <asm/sfr.h>
+
+#ifdef CONFIG_SMP
+
+/* Hook for the generic smp_call_function_many() routine. */
+void arch_send_call_function_ipi_mask(struct cpumask *mask);
+
+/* Hook for the generic smp_call_function_single() routine. */
+void arch_send_call_function_single_ipi(int cpu);
+
+void __init setup_processor(void);
+
+void smp_init_cpus(void);
+
+irqreturn_t ipi_call_interrupt(int irq, void *dev_id);
+
+#define raw_smp_processor_id() ((int) \
+ ((kvx_sfr_get(PCR) & KVX_SFR_PCR_PID_MASK) \
+ >> KVX_SFR_PCR_PID_SHIFT))
+
+#define flush_cache_vmap(start, end) do { } while (0)
+#define flush_cache_vunmap(start, end) do { } while (0)
+
+#else
+
+void smp_init_cpus(void) {}
+
+#endif /* CONFIG_SMP */
+
+#endif
diff --git a/arch/kvx/kernel/smp.c b/arch/kvx/kernel/smp.c
new file mode 100644
index 000000000000..ed4c35a8c4bc
--- /dev/null
+++ b/arch/kvx/kernel/smp.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ */
+
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/of_irq.h>
+#include <linux/cpumask.h>
+#include <linux/irq_work.h>
+#include <linux/mm_types.h>
+#include <linux/interrupt.h>
+
+#include <asm/ipi.h>
+#include <asm/tlbflush.h>
+
+enum ipi_message_type {
+ IPI_RESCHEDULE,
+ IPI_CALL_FUNC,
+ IPI_IRQ_WORK,
+ IPI_MAX
+};
+
+/* A collection of single bit ipi messages. */
+static struct {
+ unsigned long bits ____cacheline_aligned;
+} ipi_data[NR_CPUS] __cacheline_aligned;
+
+static void send_ipi_message(const struct cpumask *mask,
+ enum ipi_message_type operation)
+{
+ unsigned long flags;
+ int cpu;
+
+ /* Set operation that must be done by receiver */
+ for_each_cpu(cpu, mask)
+ set_bit(operation, &ipi_data[cpu].bits);
+
+ /* Commit the write before sending IPI */
+ smp_wmb();
+
+ local_irq_save(flags);
+
+ kvx_ipi_send(mask);
+
+ local_irq_restore(flags);
+}
+
+void arch_send_call_function_ipi_mask(struct cpumask *mask)
+{
+ send_ipi_message(mask, IPI_CALL_FUNC);
+}
+
+void arch_send_call_function_single_ipi(int cpu)
+{
+ send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);
+}
+
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+ send_ipi_message(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+}
+#endif
+
+static void ipi_stop(void *unused)
+{
+ local_cpu_stop();
+}
+
+void smp_send_stop(void)
+{
+ struct cpumask targets;
+
+ cpumask_copy(&targets, cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), &targets);
+
+ smp_call_function_many(&targets, ipi_stop, NULL, 0);
+}
+
+void smp_send_reschedule(int cpu)
+{
+ send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
+}
+
+irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
+{
+ unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
+
+ while (true) {
+ unsigned long ops = xchg(pending_ipis, 0);
+
+ if (ops == 0)
+ return IRQ_HANDLED;
+
+ if (ops & (1 << IPI_RESCHEDULE))
+ scheduler_ipi();
+
+ if (ops & (1 << IPI_CALL_FUNC))
+ generic_smp_call_function_interrupt();
+
+ if (ops & (1 << IPI_IRQ_WORK))
+ irq_work_run();
+
+ BUG_ON((ops >> IPI_MAX) != 0);
+ }
+
+ return IRQ_HANDLED;
+}
diff --git a/arch/kvx/kernel/smpboot.c b/arch/kvx/kernel/smpboot.c
new file mode 100644
index 000000000000..987a6f014163
--- /dev/null
+++ b/arch/kvx/kernel/smpboot.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ * Julian Vetter
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/sched.h>
+#include <linux/cpumask.h>
+#include <linux/sched/mm.h>
+#include <linux/mm_types.h>
+#include <linux/of_platform.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/pwr_ctrl.h>
+#include <asm/tlbflush.h>
+#include <asm/ipi.h>
+
+void *__cpu_up_stack_pointer[NR_CPUS];
+void *__cpu_up_task_pointer[NR_CPUS];
+
+void __init smp_prepare_boot_cpu(void)
+{
+}
+
+int __cpu_up(unsigned int cpu, struct task_struct *tidle)
+{
+ __cpu_up_stack_pointer[cpu] = task_stack_page(tidle) + THREAD_SIZE;
+ __cpu_up_task_pointer[cpu] = tidle;
+ /* We need to be sure writes are committed */
+ smp_mb();
+
+ kvx_pwr_ctrl_cpu_poweron(cpu);
+ while (!cpu_online(cpu))
+ cpu_relax();
+
+ return 0;
+}
+
+void __init smp_cpus_done(unsigned int max_cpus)
+{
+}
+
+void __init smp_init_cpus(void)
+{
+ struct cpumask cpumask;
+ struct device_node *cpu;
+ const __be32 *reg;
+ u32 cpu_num;
+ unsigned int nr_cpus = 0;
+
+ cpumask_clear(&cpumask);
+
+ for_each_of_cpu_node(cpu) {
+ if (!of_device_is_available(cpu))
+ continue;
+
+ reg = of_get_property(cpu, "reg", NULL);
+ if (!reg)
+ continue;
+
+ cpu_num = be32_to_cpup(reg);
+ if (cpu_num >= nr_cpu_ids)
+ continue;
+
+ nr_cpus++;
+ cpumask_set_cpu(cpu_num, &cpumask);
+ }
+
+ pr_info("%d possible cpus\n", nr_cpus);
+ init_cpu_possible(&cpumask);
+}
+
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+ if (num_present_cpus() <= 1)
+ init_cpu_present(cpu_possible_mask);
+}
+
+int __init setup_smp(void)
+{
+ int ret;
+
+ ret = kvx_pwr_ctrl_probe();
+ if (ret)
+ panic("Failed to probe power controller !");
+
+ ret = kvx_ipi_ctrl_probe(ipi_call_interrupt);
+ if (ret)
+ panic("Failed to probe IPI controller !");
+
+ return 0;
+}
+
+early_initcall(setup_smp);
+
+/*
+ * C entry point for a secondary processor.
+ */
+void __init start_kernel_secondary(void)
+{
+ struct mm_struct *mm = &init_mm;
+ unsigned int cpu = smp_processor_id();
+
+ setup_processor();
+ kvx_mmu_early_setup();
+
+ /* All kernel threads share the same mm context. */
+ mmgrab(mm);
+ current->active_mm = mm;
+ cpumask_set_cpu(cpu, mm_cpumask(mm));
+
+ notify_cpu_starting(cpu);
+ set_cpu_online(cpu, true);
+ trace_hardirqs_off();
+
+ local_flush_tlb_all();
+
+ local_irq_enable();
+ cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f61447913db9..f5a484547b15 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -152,6 +152,7 @@ enum cpuhp_state {
CPUHP_AP_IRQ_RISCV_STARTING,
CPUHP_AP_IRQ_LOONGARCH_STARTING,
CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
+ CPUHP_AP_IRQ_KVX_STARTING,
CPUHP_AP_ARM_MVEBU_COHERENCY,
CPUHP_AP_MICROCODE_LOADER,
CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
@@ -189,6 +190,7 @@ enum cpuhp_state {
CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING,
CPUHP_AP_KVM_ARM_VGIC_STARTING,
CPUHP_AP_KVM_ARM_TIMER_STARTING,
+ CPUHP_AP_KVX_TIMER_STARTING,
/* Must be the last timer callback */
CPUHP_AP_DUMMY_TIMER_STARTING,
CPUHP_AP_ARM_XEN_STARTING,
--
2.37.2
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