| Message ID | 2b0795b40d8b348d2480ee1da2d6634decbdac83.1462809819.git.joseph.salisbury@canonical.com |
|---|---|
| State | New |
| Headers | show |
On 09/05/16 17:17, Joseph Salisbury wrote: > From: Thomas Gleixner <tglx@linutronix.de> > > BugLink: http://bugs.launchpad.net/bugs/1573231 > > 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. > > 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> > Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com> > --- > 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 a61a97a..96f49a2 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); > > /* > Seems like a sane fix/workaround to the issue. Acked-by: Colin Ian King <colin.king@canonical.com>
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index a61a97a..96f49a2 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); /*