lwn.git/arch/riscv/kernel/cpu-hotplug.c, branch master

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

riscv: cpu-hotplug: clear cpu from numa map when teardown

2022-02-10T17:16:50+00:00

There is numa_add_cpu() when cpus online, accordingly, there should be numa_remove_cpu() when cpus offline. Signed-off-by: Pingfan Liu Fixes: 4f0e8eef772e ("riscv: Add numa support for riscv64 platform") Cc: stable@vger.kernel.org [Palmer: Add missing NUMA include] Signed-off-by: Palmer Dabbelt