[PATCH 6.6 036/396] powerpc/smp: Increase nr_cpu_ids to include the boot CPU

Greg Kroah-Hartman
2024-04-01T16:36:35Z

From: Michael Ellerman <mpe@ellerman.id.au>

[ Upstream commit 777f81f0a9c780a6443bcf2c7785f0cc2e87c1ef ]

If nr_cpu_ids is too low to include the boot CPU adjust nr_cpu_ids
upward. Otherwise the kernel will BUG when trying to allocate a paca
for the boot CPU and fail to boot.

Cc: stable@vger.kernel.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231229120107.2281153-2-mpe@ellerman.id.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/kernel/prom.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 58e80076bed5c..77364729a1b61 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -381,6 +381,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
nr_cpu_ids);
}

+ if (boot_cpuid >= nr_cpu_ids) {
+ set_nr_cpu_ids(min(CONFIG_NR_CPUS, ALIGN(boot_cpuid + 1, nthreads)));
+ pr_warn("Boot CPU %d >= nr_cpu_ids, adjusted nr_cpu_ids to %d\n",
+ boot_cpuid, nr_cpu_ids);
+ }
+
/*
* PAPR defines "logical" PVR values for cpus that
* meet various levels of the architecture:
--
2.43.0