From 1e90a13d0c3dc94512af1ccb2b6563e8297838fa Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 29 Oct 2016 13:42:42 +0200 Subject: [PATCH] x86/smpboot: Init apic mapping before usage The recent changes, which forced the registration of the boot cpu on UP systems, which do not have ACPI tables, have been fixed for systems w/o local APIC, but left a wreckage for systems which have neither ACPI nor mptables, but the CPU has an APIC, e.g. virtualbox. The boot process crashes in prefill_possible_map() as it wants to register the boot cpu, which needs to access the local apic, but the local APIC is not yet mapped. There is no reason why init_apic_mapping() can't be invoked before prefill_possible_map(). So instead of playing another silly early mapping game, as the ACPI/mptables code does, we just move init_apic_mapping() before the call to prefill_possible_map(). In hindsight, I should have noticed that combination earlier. Sorry for the churn (also in stable)! Fixes: ff8560512b8d ("x86/boot/smp: Don't try to poke disabled/non-existent APIC") Reported-and-debugged-by: Michal Necasek Reported-and-tested-by: Wolfgang Bauer Cc: prarit@redhat.com Cc: ville.syrjala@linux.intel.com Cc: michael.thayer@oracle.com Cc: knut.osmundsen@oracle.com Cc: frank.mehnert@oracle.com Cc: Borislav Petkov Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1610282114380.5053@nanos Signed-off-by: Thomas Gleixner --- arch/x86/kernel/setup.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index bbfbca5fea0c..9c337b0e8ba7 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1221,11 +1221,16 @@ void __init setup_arch(char **cmdline_p) */ get_smp_config(); + /* + * Systems w/o ACPI and mptables might not have it mapped the local + * APIC yet, but prefill_possible_map() might need to access it. + */ + init_apic_mappings(); + prefill_possible_map(); init_cpu_to_node(); - init_apic_mappings(); io_apic_init_mappings(); kvm_guest_init();