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authorThomas Gleixner <tglx@linutronix.de>2016-05-06 20:48:16 +0200
committerThomas Gleixner <tglx@linutronix.de>2016-05-07 10:06:55 +0200
commit56402d63eefe22179f7311a51ff2094731420406 (patch)
tree0466e2d9dc3205256269aff0bebf137669aa5f3f
parent07837831047fb72856d1f61a726a4094397facd8 (diff)
downloadlinux-stericsson-56402d63eefe22179f7311a51ff2094731420406.tar.gz
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>
-rw-r--r--arch/x86/kernel/smpboot.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index a2065d3b3b39..0e4329ed91ef 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -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);
/*