6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Fernando Fernandez Mancera <ffmancera@xxxxxxxxxx>
commit 73da582a476ea6e3512f89f8ed57dfed945829a2 upstream.
The rework of possible CPUs management erroneously disabled SMP when the
IO/APIC is disabled either by the 'noapic' command line parameter or during
IO/APIC setup. SMP is possible without IO/APIC.
Remove the ioapic_is_disabled conditions from the relevant possible CPU
management code paths to restore the orgininal behaviour.
Fixes: 7c0edad3643f ("x86/cpu/topology: Rework possible CPU management")
Signed-off-by: Fernando Fernandez Mancera <ffmancera@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/20241202145905.1482-1-ffmancera@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/topology.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -428,8 +428,8 @@ void __init topology_apply_cmdline_limit
{
unsigned int possible = nr_cpu_ids;
- /* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' 'noapic' */
- if (!setup_max_cpus || ioapic_is_disabled || apic_is_disabled)
+ /* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' */
+ if (!setup_max_cpus || apic_is_disabled)
possible = 1;
/* 'possible_cpus=N' */
@@ -443,7 +443,7 @@ void __init topology_apply_cmdline_limit
static __init bool restrict_to_up(void)
{
- if (!smp_found_config || ioapic_is_disabled)
+ if (!smp_found_config)
return true;
/*
* XEN PV is special as it does not advertise the local APIC
