pvclock_gtod_sync_lock can be taken with interrupts disabled if the preempt notifier calls get_kvmclock_ns to update the Xen runstate information: spin_lock include/linux/spinlock.h:354 [inline] get_kvmclock_ns+0x25/0x390 arch/x86/kvm/x86.c:2587 kvm_xen_update_runstate+0x3d/0x2c0 arch/x86/kvm/xen.c:69 kvm_xen_update_runstate_guest+0x74/0x320 arch/x86/kvm/xen.c:100 kvm_xen_runstate_set_preempted arch/x86/kvm/xen.h:96 [inline] kvm_arch_vcpu_put+0x2d8/0x5a0 arch/x86/kvm/x86.c:4062 So change the users of the spinlock to spin_lock_irqsave and spin_unlock_irqrestore. Before doing that, patch 1 just makes the pvclock_gtod_sync_lock critical sections as small as possible so that the resulting irq-disabled sections are easier to review. Paolo Paolo Bonzini (2): KVM: x86: reduce pvclock_gtod_sync_lock critical sections KVM: x86: disable interrupts while pvclock_gtod_sync_lock is taken arch/x86/kvm/x86.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) -- 2.26.2
