Commit 56402d63 authored May 06, 2016 by Thomas Gleixner

x86/topology: Handle CPUID bogosity gracefully



Joseph reported that a XEN guest dies with a division by 0 in the package
topology setup code. This happens if cpu_info.x86_max_cores is zero.

Handle that case and emit a warning. This does not fix the underlying XEN bug,
but makes the code more robust.

Reported-and-tested-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1605062046270.3540@nanos


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

parent 07837831

arch/x86/kernel/smpboot.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -332,6 +332,11 @@ static void __init smp_init_package_map(void)
		* primary cores.
		*/
		ncpus = boot_cpu_data.x86_max_cores;
		if (!ncpus) {
		pr_warn("x86_max_cores == zero !?!?");
		ncpus = 1;
		}

		__max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus);

		/*