Commit 1e90a13d authored Oct 29, 2016 by Thomas Gleixner

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: ff856051 ("x86/boot/smp: Don't try to poke disabled/non-existent APIC")
Reported-and-debugged-by: Michal Necasek <michal.necasek@oracle.com>
Reported-and-tested-by: Wolfgang Bauer <wbauer@tmo.at>
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 <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1610282114380.5053@nanos


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent c067affc

arch/x86/kernel/setup.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -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();

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