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/kernel/cpu_ops_sbi.c | |
| parent | cfafe260137418d0265d0df3bb18dc494af2b43e (diff) | |
| download | lwn-f1e58583b9c7ceae7f11646e9edf2561d67f29c9.tar.gz lwn-f1e58583b9c7ceae7f11646e9edf2561d67f29c9.zip | |
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/kernel/cpu_ops_sbi.c')
| -rw-r--r-- | arch/riscv/kernel/cpu_ops_sbi.c | 34 |
1 files changed, 34 insertions, 0 deletions
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 }; |