diff options
| author | Atish Patra <atish.patra@wdc.com> | 2020-03-17 18:11:44 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-03-31 11:28:30 -0700 |
| commit | f1e58583b9c7ceae7f11646e9edf2561d67f29c9 (patch) | |
| tree | bb55d2b26e3eefea34f6d672cff66b01211d95be /arch/riscv/include | |
| parent | cfafe260137418d0265d0df3bb18dc494af2b43e (diff) | |
RISC-V: Support cpu hotplug
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 <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Diffstat (limited to 'arch/riscv/include')
| -rw-r--r-- | arch/riscv/include/asm/cpu_ops.h | 12 | ||||
| -rw-r--r-- | arch/riscv/include/asm/smp.h | 17 |
2 files changed, 29 insertions, 0 deletions
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 */ |