[PATCH 6.6 035/396] powerpc/smp: Adjust nr_cpu_ids to cover all threads of a core

Greg Kroah-Hartman
2024-04-01T16:36:32Z

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

[ Upstream commit 5580e96dad5a439d561d9648ffcbccb739c2a120 ]

If nr_cpu_ids is too low to include at least all the threads of a single
core adjust nr_cpu_ids upwards. This avoids triggering odd bugs in code
that assumes all threads of a core are available.

Cc: stable@vger.kernel.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231229120107.2281153-1-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 0b5878c3125b1..58e80076bed5c 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -375,6 +375,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
if (IS_ENABLED(CONFIG_PPC64))
boot_cpu_hwid = be32_to_cpu(intserv[found_thread]);

+ if (nr_cpu_ids % nthreads != 0) {
+ set_nr_cpu_ids(ALIGN(nr_cpu_ids, nthreads));
+ pr_warn("nr_cpu_ids was not a multiple of threads_per_core, adjusted to %d\n",
+ nr_cpu_ids);
+ }
+
/*
* PAPR defines "logical" PVR values for cpus that
* meet various levels of the architecture:
--
2.43.0