stro kernel. https://universe.0xinfinity.dev/distro/kernel/atom?h=linux-6.19.y 2024-08-01T14:15:43Z RISC-V: Enable the IPI before workqueue_online_cpu() 2024-08-01T14:15:43Z Nick Hu nick.hu@sifive.com 2024-07-17T03:17:14Z urn:sha1:3908ba2e0b2476e2ec13e15967bf6a37e449f2af Sometimes the hotplug cpu stalls at the arch_cpu_idle() for a while after workqueue_online_cpu(). When cpu stalls at the idle loop, the reschedule IPI is pending. However the enable bit is not enabled yet so the cpu stalls at WFI until watchdog timeout. Therefore enable the IPI before the workqueue_online_cpu() to fix the issue. Fixes: 63c5484e7495 ("workqueue: Add multiple affinity scopes and interface to select them") Signed-off-by: Nick Hu <nick.hu@sifive.com> Reviewed-by: Anup Patel <anup@brainfault.org> Link: https://lore.kernel.org/r/20240717031714.1946036-1-nick.hu@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> riscv: Use IPIs for remote cache/TLB flushes by default 2024-04-29T17:49:26Z Samuel Holland samuel.holland@sifive.com 2024-03-27T04:49:44Z urn:sha1:dc892fb443224da7018891a5fac9cb6ac50c14b3 An IPI backend is always required in an SMP configuration, but an SBI implementation is not. For example, SBI will be unavailable when the kernel runs in M mode. For this reason, consider IPI delivery of cache and TLB flushes to be the base case, and any other implementation (such as the SBI remote fence extension) to be an optimization. Generally, if IPIs can be delivered without firmware assistance, they are assumed to be faster than SBI calls due to the SBI context switch overhead. However, when SBI is used as the IPI backend, then the context switch cost must be paid anyway, and performing the cache/TLB flush directly in the SBI implementation is more efficient than injecting an interrupt to S-mode. This is the only existing scenario where riscv_ipi_set_virq_range() is called with use_for_rfence set to false. sbi_ipi_init() already checks riscv_ipi_have_virq_range(), so it only calls riscv_ipi_set_virq_range() when no other IPI device is available. This allows moving the static key and dropping the use_for_rfence parameter. This decouples the static key from the irqchip driver probe order. Furthermore, the static branch only makes sense when CONFIG_RISCV_SBI is enabled. Optherwise, IPIs must be used. Add a fallback definition of riscv_use_sbi_for_rfence() which handles this case and removes the need to check CONFIG_RISCV_SBI elsewhere, such as in cacheflush.c. Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240327045035.368512-4-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>