linux-stable.git/arch/riscv/kernel/cpu-hotplug.c, branch linux-rolling-stable

riscv: cpu_ops: Change return value type of cpu_is_stopped() to bool

2026-07-24T14:19:36+00:00

[ Upstream commit 2b2b207e1162e577cd6208e184d3d3a0fcfa9cca ]

In the original sbi_cpu_is_stopped(), if rc doesn't equal to the
SBI_HSM_STATE_STOPPED, it will return rc to the caller directly. But
there is a hidden problem, the rc could be SBI_HSM_STATE_STARTED, if
so, this function will report cpu stopped while the cpu isn't really
stopped.

Furthermore, from the name of cpu_is_stopped(), it gives a sense the
return value is a bool type, true means the cpu is stopped, conversely
false means the cpu is not stopped.

Here change the return value type to bool and change the callers
accordingly. This could fix the above two issues.

Fixes: f1e58583b9c7c ("RISC-V: Support cpu hotplug")
Signed-off-by: Hui Wang 
Link: https://patch.msgid.link/20260413123515.48423-1-hui.wang@canonical.com
[pjw@kernel.org: cleaned up some of the pr_warn() messages]
Signed-off-by: Paul Walmsley 
Signed-off-by: Sasha Levin

riscv: remove redundant #ifdef check in cpu-hotplug

2026-04-05T00:42:41+00:00

The cpu-hotplug.c only is built when CONFIG_HOTPLUG_CPU is defined,
it is not needed to check HOTPLUG_CPU in this file.

Signed-off-by: Hui Wang 
Link: https://patch.msgid.link/20260304033403.238012-2-hui.wang@canonical.com
[pjw@kernel.org: removed extra whitespace at EOF]
Signed-off-by: Paul Walmsley

RISC-V: clear hot-unplugged cores from all task mm_cpumasks to avoid rfence errors

2025-10-10T01:36:45+00:00

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 
Reviewed-by: Andrew Jones 
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

riscv: Use '%u' to format the output of 'cpu'

2024-10-25T13:18:40+00:00

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

Suggested-by: Wentao Guan 
Suggested-by: Maciej W. Rozycki 
Link: https://lore.kernel.org/all/alpine.DEB.2.21.2409122309090.40372@angie.orcam.me.uk/
Signed-off-by: WangYuli 
Reviewed-by: Charlie Jenkins 
Tested-by: Charlie Jenkins 
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

riscv: Use the same CPU operations for all CPUs

2024-01-04T23:03:07+00:00

RISC-V provides no binding (ACPI or DT) to describe per-cpu start/stop
operations, so cpu_set_ops() will always detect the same operations for
every CPU. Replace the cpu_ops array with a single pointer to save space
and reduce boot time.

Signed-off-by: Samuel Holland 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20231121234736.3489608-4-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt

riscv: Remove unused members from struct cpu_operations

2024-01-04T23:03:06+00:00

name is not used anywhere at all. cpu_prepare and cpu_disable do nothing
and always return 0 if implemented.

Signed-off-by: Samuel Holland 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20231121234736.3489608-3-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt

riscv: Switch to hotplug core state synchronization

2023-05-15T11:44:59+00:00

Switch to the CPU hotplug core state tracking and synchronization
mechanim. No functional change intended.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Palmer Dabbelt 
Tested-by: Michael Kelley 
Tested-by: Oleksandr Natalenko 
Tested-by: Helge Deller  # parisc
Tested-by: Guilherme G. Piccoli  # Steam Deck
Link: https://lore.kernel.org/r/20230512205256.916055844@linutronix.de

Merge tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-04-28T21:02:54+00:00

Pull objtool updates from Ingo Molnar:

 - Mark arch_cpu_idle_dead() __noreturn, make all architectures &
   drivers that did this inconsistently follow this new, common
   convention, and fix all the fallout that objtool can now detect
   statically

 - Fix/improve the ORC unwinder becoming unreliable due to
   UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK
   and UNWIND_HINT_UNDEFINED to resolve it

 - Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code

 - Generate ORC data for __pfx code

 - Add more __noreturn annotations to various kernel startup/shutdown
   and panic functions

 - Misc improvements & fixes

* tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
  x86/hyperv: Mark hv_ghcb_terminate() as noreturn
  scsi: message: fusion: Mark mpt_halt_firmware() __noreturn
  x86/cpu: Mark {hlt,resume}_play_dead() __noreturn
  btrfs: Mark btrfs_assertfail() __noreturn
  objtool: Include weak functions in global_noreturns check
  cpu: Mark nmi_panic_self_stop() __noreturn
  cpu: Mark panic_smp_self_stop() __noreturn
  arm64/cpu: Mark cpu_park_loop() and friends __noreturn
  x86/head: Mark *_start_kernel() __noreturn
  init: Mark start_kernel() __noreturn
  init: Mark [arch_call_]rest_init() __noreturn
  objtool: Generate ORC data for __pfx code
  x86/linkage: Fix padding for typed functions
  objtool: Separate prefix code from stack validation code
  objtool: Remove superfluous dead_end_function() check
  objtool: Add symbol iteration helpers
  objtool: Add WARN_INSN()
  scripts/objdump-func: Support multiple functions
  context_tracking: Fix KCSAN noinstr violation
  objtool: Add stackleak instrumentation to uaccess safe list
  ...

RISC-V: Treat IPIs as normal Linux IRQs

2023-04-08T10:26:24+00:00

Currently, the RISC-V kernel provides arch specific hooks (i.e.
struct riscv_ipi_ops) to register IPI handling methods. The stats
gathering of IPIs is also arch specific in the RISC-V kernel.

Other architectures (such as ARM, ARM64, and MIPS) have moved away
from custom arch specific IPI handling methods. Currently, these
architectures have Linux irqchip drivers providing a range of Linux
IRQ numbers to be used as IPIs and IPI triggering is done using
generic IPI APIs. This approach allows architectures to treat IPIs
as normal Linux IRQs and IPI stats gathering is done by the generic
Linux IRQ subsystem.

We extend the RISC-V IPI handling as-per above approach so that arch
specific IPI handling methods (struct riscv_ipi_ops) can be removed
and the IPI handling is done through the Linux IRQ subsystem.

Signed-off-by: Anup Patel 
Acked-by: Palmer Dabbelt 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20230328035223.1480939-4-apatel@ventanamicro.com

sched/idle: Mark arch_cpu_idle_dead() __noreturn

2023-03-08T16:44:28+00:00

Before commit 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead()
return"), in Xen, when a previously offlined CPU was brought back
online, it unexpectedly resumed execution where it left off in the
middle of the idle loop.

There were some hacks to make that work, but the behavior was surprising
as do_idle() doesn't expect an offlined CPU to return from the dead (in
arch_cpu_idle_dead()).

Now that Xen has been fixed, and the arch-specific implementations of
arch_cpu_idle_dead() also don't return, give it a __noreturn attribute.

This will cause the compiler to complain if an arch-specific
implementation might return.  It also improves code generation for both
caller and callee.

Also fixes the following warning:

  vmlinux.o: warning: objtool: do_idle+0x25f: unreachable instruction

Reported-by: Paul E. McKenney 
Tested-by: Paul E. McKenney 
Link: https://lore.kernel.org/r/60d527353da8c99d4cf13b6473131d46719ed16d.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf