linux.git/arch/riscv/kernel/cpu-hotplug.c, branch v5.10.258 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git RISC-V: clear hot-unplugged cores from all task mm_cpumasks to avoid rfence errors 2025-12-06T21:08:17+00:00 Danil Skrebenkov danil.skrebenkov@cloudbear.ru 2025-09-19T13:28:46+00:00 8e828122d61777bbd3b9e73a3d45806cf05668c5 [ Upstream commit ae9e9f3d67dcef7582a4524047b01e33c5185ddb ] openSBI v1.7 adds harts checks for ipi operations. Especially it adds comparison between hmask passed as an argument from linux and mask of online harts (from openSBI side). If they don't fit each other the error occurs. When cpu is offline, cpu_online_mask is explicitly cleared in __cpu_disable. However, there is no explicit clearing of mm_cpumask. mm_cpumask is used for rfence operations that call openSBI RFENCE extension which uses ipi to remote harts. If hart is offline there may be error if mask of linux is not as mask of online harts in openSBI. this patch adds explicit clearing of mm_cpumask for offline hart. Signed-off-by: Danil Skrebenkov <danil.skrebenkov@cloudbear.ru> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Link: https://lore.kernel.org/r/20250919132849.31676-1-danil.skrebenkov@cloudbear.ru [pjw@kernel.org: rewrote subject line for clarity] Signed-off-by: Paul Walmsley <pjw@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit ae9e9f3d67dcef7582a4524047b01e33c5185ddb ]

openSBI v1.7 adds harts checks for ipi operations. Especially it
adds comparison between hmask passed as an argument from linux
and mask of online harts (from openSBI side). If they don't
fit each other the error occurs.

When cpu is offline, cpu_online_mask is explicitly cleared in
__cpu_disable. However, there is no explicit clearing of
mm_cpumask. mm_cpumask is used for rfence operations that
call openSBI RFENCE extension which uses ipi to remote harts.
If hart is offline there may be error if mask of linux is not
as mask of online harts in openSBI.

this patch adds explicit clearing of mm_cpumask for offline hart.

Signed-off-by: Danil Skrebenkov <danil.skrebenkov@cloudbear.ru>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250919132849.31676-1-danil.skrebenkov@cloudbear.ru
[pjw@kernel.org: rewrote subject line for clarity]
Signed-off-by: Paul Walmsley <pjw@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
riscv: Use '%u' to format the output of 'cpu' 2024-11-08T15:22:03+00:00 WangYuli wangyuli@uniontech.com 2024-10-17T03:20:10+00:00 7e6bb344318576e7160fbf48c21fe63beed56598 [ Upstream commit e0872ab72630dada3ae055bfa410bf463ff1d1e0 ] 'cpu' is an unsigned integer, so its conversion specifier should be %u, not %d. Suggested-by: Wentao Guan <guanwentao@uniontech.com> Suggested-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://lore.kernel.org/all/alpine.DEB.2.21.2409122309090.40372@angie.orcam.me.uk/ Signed-off-by: WangYuli <wangyuli@uniontech.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Tested-by: Charlie Jenkins <charlie@rivosinc.com> Fixes: f1e58583b9c7 ("RISC-V: Support cpu hotplug") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/4C127DEECDA287C8+20241017032010.96772-1-wangyuli@uniontech.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e0872ab72630dada3ae055bfa410bf463ff1d1e0 ]

'cpu' is an unsigned integer, so its conversion specifier should
be %u, not %d.

Suggested-by: Wentao Guan <guanwentao@uniontech.com>
Suggested-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/all/alpine.DEB.2.21.2409122309090.40372@angie.orcam.me.uk/
Signed-off-by: WangYuli <wangyuli@uniontech.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Fixes: f1e58583b9c7 ("RISC-V: Support cpu hotplug")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/4C127DEECDA287C8+20241017032010.96772-1-wangyuli@uniontech.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
RISC-V: Support cpu hotplug 2020-03-31T18:28:30+00:00 Atish Patra atish.patra@wdc.com 2020-03-18T01:11:44+00:00 f1e58583b9c7ceae7f11646e9edf2561d67f29c9 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> 
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>