Commit-ID: 56402d63eefe22179f7311a51ff2094731420406 Gitweb: http://git.kernel.org/tip/56402d63eefe22179f7311a51ff2094731420406 Author: Thomas Gleixner <t...@linutronix.de> AuthorDate: Fri, 6 May 2016 20:48:16 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Sat, 7 May 2016 10:06:55 +0200
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.salisb...@canonical.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Boris Ostrovsky <boris.ostrov...@oracle.com> Cc: David Vrabel <david.vra...@citrix.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1605062046270.3540@nanos Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- arch/x86/kernel/smpboot.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index a2065d3..0e4329e 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); /*
