tree b3e083c651f09fee362d88f0d1fc140194f2431d
parent 3564990af1b9f77a63692c1079e9c41af229f066
author Marcelo Tosatti <mtosatti@redhat.com> 1207936406 -0300
committer Avi Kivity <avi@qumranet.com> 1209287051 +0300

KVM: hlt emulation should take in-kernel APIC/PIT timers into account

Timers that fire between guest hlt and vcpu_block's add_wait_queue() are
ignored, possibly resulting in hangs.

Also make sure that atomic_inc and waitqueue_active tests happen in the
specified order, otherwise the following race is open:

CPU0                                        CPU1
                                            if (waitqueue_active(wq))
add_wait_queue()
if (!atomic_read(pit_timer->pending))
    schedule()
                                            atomic_inc(pit_timer->pending)

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>