Unverified Commit 6259f344 authored Jul 03, 2023 by Marc Zyngier Committed by Palmer Dabbelt Jul 05, 2023

risc-v: Fix order of IPI enablement vs RCU startup



Conor reports that risc-v tries to enable IPIs before telling the
core code to enable RCU. With the introduction of the mapple tree
as a backing store for the irq descriptors, this results in
a very shouty boot sequence, as RCU is legitimately upset.

Restore some sanity by moving the risc_ipi_enable() call after
notify_cpu_starting(), which explicitly enables RCU on the calling
CPU.

Fixes: 832f15f4 ("RISC-V: Treat IPIs as normal Linux IRQs")
Reported-by: Conor Dooley <conor@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230703-dupe-frying-79ae2ccf94eb@spud


Cc: Anup Patel <apatel@ventanamicro.com>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230703183126.1567625-1-maz@kernel.org


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

parent 62ba41d2

arch/riscv/kernel/smpboot.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -238,10 +238,11 @@ asmlinkage __visible void smp_callin(void)
		mmgrab(mm);
		current->active_mm = mm;

		riscv_ipi_enable();

		store_cpu_topology(curr_cpuid);
		notify_cpu_starting(curr_cpuid);

		riscv_ipi_enable();

		numa_add_cpu(curr_cpuid);
		set_cpu_online(curr_cpuid, 1);
		probe_vendor_features(curr_cpuid);