From c284b42abadbb22083bfde24d308899c08d44ffa Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Wed, 21 Dec 2011 17:45:19 -0800 Subject: [PATCH] x86: Skip cpus with apic-ids >= 255 in !x2apic_mode If the x2apic mode is disabled for reasons like interrupt-remapping not available etc, then we need to skip the logical cpu bringup of apic-id's >= 255. Otherwise as the platform is in xapic mode, init/startup IPI's will consider only the low 8-bits and there is a possibility of re-sending init/startup IPI's to the logical cpu that is already online. This will avoid potential reboots/unpredictable behavior etc. Signed-off-by: Suresh Siddha Link: http://lkml.kernel.org/r/20111222014632.702932458@sbsiddha-desk.sc.intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/smpboot.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 9f548cb4a95..e38e21754ee 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -840,7 +840,8 @@ int __cpuinit native_cpu_up(unsigned int cpu) pr_debug("++++++++++++++++++++=_---CPU UP %u\n", cpu); if (apicid == BAD_APICID || apicid == boot_cpu_physical_apicid || - !physid_isset(apicid, phys_cpu_present_map)) { + !physid_isset(apicid, phys_cpu_present_map) || + (!x2apic_mode && apicid >= 255)) { printk(KERN_ERR "%s: bad cpu %d\n", __func__, cpu); return -EINVAL; }