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17 Mar 2020 18:03:29 -0700 IronPort-SDR: clNaC5M7dCm60dPiKWGH5cON7Dc675lLb5FkVokEyXl/6+0xhEz+UFEQUx802c9CdKn3wUzKDu OW+qVrfRLhg9UFH29s500YMS17ueNHZlsl/h46sacufPuW0tpTA0wMPU1uoKNw4c4QmzAEdU52 /fyewY5BCcnqhHEgSBa2jsHLLMdFZMbvyQp+u2oh9IOcKj9x3W0fa/WSR0nw/Fc2wAHVXItfIj DVHZWaroNO3VhmC8yU1mg4y8qYvLkbzf4J4EhSEH5rJ8JFC9AcWjvkc0Ma/HSkb+vkTteXdRM8 3WY= WDCIronportException: Internal Received: from mccorma-lt.ad.shared (HELO yoda.hgst.com) ([10.86.54.125]) by uls-op-cesaip01.wdc.com with ESMTP; 17 Mar 2020 18:12:02 -0700 From: Atish Patra To: linux-kernel@vger.kernel.org Subject: [PATCH v11 11/11] RISC-V: Support cpu hotplug Date: Tue, 17 Mar 2020 18:11:44 -0700 Message-Id: <20200318011144.91532-12-atish.patra@wdc.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200318011144.91532-1-atish.patra@wdc.com> References: <20200318011144.91532-1-atish.patra@wdc.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200317_181210_892890_E99B0E0F X-CRM114-Status: GOOD ( 24.00 ) X-Spam-Score: -2.5 (--) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-2.5 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [216.71.154.45 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Albert Ou , Zong Li , Nick Hu , Vincent Chen , Anup Patel , Mike Rapoport , Atish Patra , Palmer Dabbelt , Gary Guo , Paul Walmsley , Greentime Hu , linux-riscv@lists.infradead.org, Bin Meng , Thomas Gleixner , Mao Han Sender: "linux-riscv" Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org This patch enable support for cpu hotplug in RISC-V. It uses SBI HSM extension to online/offline any hart. As a result, the harts are returned to firmware once they are offline. If the harts are brought online afterwards, they re-enter Linux kernel as if a secondary hart booted for the first time. All booting requirements are honored during this process. Tested both on QEMU and HighFive Unleashed board with. Test result follows. --------------------------------------------------- Offline cpu 2 --------------------------------------------------- $ echo 0 > /sys/devices/system/cpu/cpu2/online [ 32.828684] CPU2: off $ cat /proc/cpuinfo processor : 0 hart : 0 isa : rv64imafdcsu mmu : sv48 processor : 1 hart : 1 isa : rv64imafdcsu mmu : sv48 processor : 3 hart : 3 isa : rv64imafdcsu mmu : sv48 processor : 4 hart : 4 isa : rv64imafdcsu mmu : sv48 processor : 5 hart : 5 isa : rv64imafdcsu mmu : sv48 processor : 6 hart : 6 isa : rv64imafdcsu mmu : sv48 processor : 7 hart : 7 isa : rv64imafdcsu mmu : sv48 --------------------------------------------------- online cpu 2 --------------------------------------------------- $ echo 1 > /sys/devices/system/cpu/cpu2/online $ cat /proc/cpuinfo processor : 0 hart : 0 isa : rv64imafdcsu mmu : sv48 processor : 1 hart : 1 isa : rv64imafdcsu mmu : sv48 processor : 2 hart : 2 isa : rv64imafdcsu mmu : sv48 processor : 3 hart : 3 isa : rv64imafdcsu mmu : sv48 processor : 4 hart : 4 isa : rv64imafdcsu mmu : sv48 processor : 5 hart : 5 isa : rv64imafdcsu mmu : sv48 processor : 6 hart : 6 isa : rv64imafdcsu mmu : sv48 processor : 7 hart : 7 isa : rv64imafdcsu mmu : sv48 Signed-off-by: Atish Patra Reviewed-by: Anup Patel --- arch/riscv/Kconfig | 12 ++++- arch/riscv/include/asm/cpu_ops.h | 12 +++++ arch/riscv/include/asm/smp.h | 17 +++++++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/cpu-hotplug.c | 87 ++++++++++++++++++++++++++++++++ arch/riscv/kernel/cpu_ops_sbi.c | 34 +++++++++++++ arch/riscv/kernel/setup.c | 19 ++++++- 7 files changed, 180 insertions(+), 2 deletions(-) create mode 100644 arch/riscv/kernel/cpu-hotplug.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 20c6191399ea..b3daadd116ec 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -20,7 +20,6 @@ config RISCV select CLONE_BACKWARDS select COMMON_CLK select GENERIC_CLOCKEVENTS - select GENERIC_CPU_DEVICES select GENERIC_IRQ_SHOW select GENERIC_PCI_IOMAP select GENERIC_SCHED_CLOCK @@ -248,6 +247,17 @@ config NR_CPUS depends on SMP default "8" +config HOTPLUG_CPU + bool "Support for hot-pluggable CPUs" + depends on SMP + select GENERIC_IRQ_MIGRATION + help + + Say Y here to experiment with turning CPUs off and on. CPUs + can be controlled through /sys/devices/system/cpu. + + Say N if you want to disable CPU hotplug. + choice prompt "CPU Tuning" default TUNE_GENERIC diff --git a/arch/riscv/include/asm/cpu_ops.h b/arch/riscv/include/asm/cpu_ops.h index 5ce81a28e1d9..a8ec3c5c1bd2 100644 --- a/arch/riscv/include/asm/cpu_ops.h +++ b/arch/riscv/include/asm/cpu_ops.h @@ -18,12 +18,24 @@ * is a mechanism for doing so, tests whether it is * possible to boot the given HART. * @cpu_start: Boots a cpu into the kernel. + * @cpu_disable: Prepares a cpu to die. May fail for some + * mechanism-specific reason, which will cause the hot + * unplug to be aborted. Called from the cpu to be killed. + * @cpu_stop: Makes a cpu leave the kernel. Must not fail. Called from + * the cpu being stopped. + * @cpu_is_stopped: Ensures a cpu has left the kernel. Called from another + * cpu. */ struct cpu_operations { const char *name; int (*cpu_prepare)(unsigned int cpu); int (*cpu_start)(unsigned int cpu, struct task_struct *tidle); +#ifdef CONFIG_HOTPLUG_CPU + int (*cpu_disable)(unsigned int cpu); + void (*cpu_stop)(void); + int (*cpu_is_stopped)(unsigned int cpu); +#endif }; extern const struct cpu_operations *cpu_ops[NR_CPUS]; diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h index 023f74fb8b3b..f4c7cfda6b7f 100644 --- a/arch/riscv/include/asm/smp.h +++ b/arch/riscv/include/asm/smp.h @@ -43,6 +43,13 @@ void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out); */ #define raw_smp_processor_id() (current_thread_info()->cpu) +#if defined CONFIG_HOTPLUG_CPU +int __cpu_disable(void); +void __cpu_die(unsigned int cpu); +void cpu_stop(void); +#else +#endif /* CONFIG_HOTPLUG_CPU */ + #else static inline void show_ipi_stats(struct seq_file *p, int prec) @@ -69,4 +76,14 @@ static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in, } #endif /* CONFIG_SMP */ + +#if defined(CONFIG_HOTPLUG_CPU) && (CONFIG_SMP) +bool cpu_has_hotplug(unsigned int cpu); +#else +static inline bool cpu_has_hotplug(unsigned int cpu) +{ + return false; +} +#endif + #endif /* _ASM_RISCV_SMP_H */ diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index a0be34b96846..9601ac907f70 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -47,5 +47,6 @@ obj-$(CONFIG_RISCV_SBI) += sbi.o ifeq ($(CONFIG_RISCV_SBI), y) obj-$(CONFIG_SMP) += cpu_ops_sbi.o endif +obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o clean: diff --git a/arch/riscv/kernel/cpu-hotplug.c b/arch/riscv/kernel/cpu-hotplug.c new file mode 100644 index 000000000000..df84e0c13db1 --- /dev/null +++ b/arch/riscv/kernel/cpu-hotplug.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020 Western Digital Corporation or its affiliates. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +void cpu_stop(void); +void arch_cpu_idle_dead(void) +{ + cpu_stop(); +} + +bool cpu_has_hotplug(unsigned int cpu) +{ + if (cpu_ops[cpu]->cpu_stop) + return true; + + return false; +} + +/* + * __cpu_disable runs on the processor to be shutdown. + */ +int __cpu_disable(void) +{ + int ret = 0; + unsigned int cpu = smp_processor_id(); + + if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_stop) + return -EOPNOTSUPP; + + if (cpu_ops[cpu]->cpu_disable) + ret = cpu_ops[cpu]->cpu_disable(cpu); + + if (ret) + return ret; + + remove_cpu_topology(cpu); + set_cpu_online(cpu, false); + irq_migrate_all_off_this_cpu(); + + return ret; +} + +/* + * Called on the thread which is asking for a CPU to be shutdown. + */ +void __cpu_die(unsigned int cpu) +{ + int ret = 0; + + if (!cpu_wait_death(cpu, 5)) { + pr_err("CPU %u: didn't die\n", cpu); + return; + } + pr_notice("CPU%u: off\n", cpu); + + /* Verify from the firmware if the cpu is really stopped*/ + if (cpu_ops[cpu]->cpu_is_stopped) + ret = cpu_ops[cpu]->cpu_is_stopped(cpu); + if (ret) + pr_warn("CPU%d may not have stopped: %d\n", cpu, ret); +} + +/* + * Called from the idle thread for the CPU which has been shutdown. + */ +void cpu_stop(void) +{ + idle_task_exit(); + + (void)cpu_report_death(); + + cpu_ops[smp_processor_id()]->cpu_stop(); + /* It should never reach here */ + BUG(); +} diff --git a/arch/riscv/kernel/cpu_ops_sbi.c b/arch/riscv/kernel/cpu_ops_sbi.c index 66f3cded91f5..685fae72b7f5 100644 --- a/arch/riscv/kernel/cpu_ops_sbi.c +++ b/arch/riscv/kernel/cpu_ops_sbi.c @@ -74,8 +74,42 @@ static int sbi_cpu_prepare(unsigned int cpuid) return 0; } +#ifdef CONFIG_HOTPLUG_CPU +static int sbi_cpu_disable(unsigned int cpuid) +{ + if (!cpu_ops_sbi.cpu_stop) + return -EOPNOTSUPP; + return 0; +} + +static void sbi_cpu_stop(void) +{ + int ret; + + ret = sbi_hsm_hart_stop(); + pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret); +} + +static int sbi_cpu_is_stopped(unsigned int cpuid) +{ + int rc; + int hartid = cpuid_to_hartid_map(cpuid); + + rc = sbi_hsm_hart_get_status(hartid); + + if (rc == SBI_HSM_HART_STATUS_STOPPED) + return 0; + return rc; +} +#endif + const struct cpu_operations cpu_ops_sbi = { .name = "sbi", .cpu_prepare = sbi_cpu_prepare, .cpu_start = sbi_cpu_start, +#ifdef CONFIG_HOTPLUG_CPU + .cpu_disable = sbi_cpu_disable, + .cpu_stop = sbi_cpu_stop, + .cpu_is_stopped = sbi_cpu_is_stopped, +#endif }; diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 44ac4ddf60ab..1d2f66579b94 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -16,12 +16,13 @@ #include #include #include +#include #include +#include #include #include #include -#include #include #include #include @@ -43,6 +44,7 @@ struct screen_info screen_info = { /* The lucky hart to first increment this variable will boot the other cores */ atomic_t hart_lottery; unsigned long boot_cpu_hartid; +static DEFINE_PER_CPU(struct cpu, cpu_devices); void __init parse_dtb(void) { @@ -90,3 +92,18 @@ void __init setup_arch(char **cmdline_p) riscv_fill_hwcap(); } + +static int __init topology_init(void) +{ + int i; + + for_each_possible_cpu(i) { + struct cpu *cpu = &per_cpu(cpu_devices, i); + + cpu->hotpluggable = cpu_has_hotplug(i); + register_cpu(cpu, i); + } + + return 0; +} +subsys_initcall(topology_init);