if during CPU hotplug master CPU had errors during sending AP wake up IPIs, it fails hotplug operation. But AP might start and spin on never set cpu_callout_mask indefinitely, consuming power or host VCPU resources needlessly.
On the other hand, master CPU marks AP with BAD_APICID if hotplug attempt failed, so use this fact to halt CPU to avoid needless spinning. Signed-off-by: Igor Mammedov <[email protected]> --- arch/x86/kernel/cpu/common.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e048e87..9f07b8e 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1242,8 +1242,11 @@ void cpu_init(void) * wait till the master CPU completes it's STARTUP sequence, * and decides to wait till this AP boots */ - while (!cpumask_test_cpu(cpu, cpu_callout_mask)) + while (!cpumask_test_cpu(cpu, cpu_callout_mask)) { cpu_relax(); + if (per_cpu(x86_cpu_to_apicid, cpu) == BAD_APICID) + halt(); + } /* * Load microcode on this cpu if a valid microcode is available. @@ -1345,8 +1348,11 @@ void cpu_init(void) * wait till the master CPU completes it's STARTUP sequence, * and decides to wait till this AP boots */ - while (!cpumask_test_cpu(cpu, cpu_callout_mask)) + while (!cpumask_test_cpu(cpu, cpu_callout_mask)) { cpu_relax(); + if (per_cpu(x86_cpu_to_apicid, cpu) == BAD_APICID) + halt(); + } show_ucode_info_early(); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
