The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 73da582a476ea6e3512f89f8ed57dfed945829a2 Gitweb: https://git.kernel.org/tip/73da582a476ea6e3512f89f8ed57dfed945829a2 Author: Fernando Fernandez Mancera ffmancera@riseup.net AuthorDate: Mon, 02 Dec 2024 14:58:45 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Thu, 05 Dec 2024 14:43:32 +01:00

x86/cpu/topology: Remove limit of CPUs due to disabled IO/APIC

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 --- arch/x86/kernel/cpu/topology.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 621a151..b2e313e 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -428,8 +428,8 @@ void __init topology_apply_cmdline_limits_early(void) { 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_limits_early(void)

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