6.12-stable review patch. If anyone has any objections, please let me know.
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From: Fernando Fernandez Mancera ffmancera@riseup.net
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@riseup.net Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20241202145905.1482-1-ffmancera@riseup.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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