From 931f261b42f10c8c8c9ab53f5ceb47ce51af7cf5 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Sat, 17 Dec 2016 18:43:52 +0100 Subject: [PATCH] kvm: fix schedule in atomic in kvm_steal_time_set_preempted() kvm_steal_time_set_preempted() isn't disabling the pagefaults before calling __copy_to_user and the kernel debug notices. Signed-off-by: Andrea Arcangeli Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 49da1064ef50..8ce1139a08b5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2844,7 +2844,17 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { + /* + * Disable page faults because we're in atomic context here. + * kvm_write_guest_offset_cached() would call might_fault() + * that relies on pagefault_disable() to tell if there's a + * bug. NOTE: the write to guest memory may not go through if + * during postcopy live migration or if there's heavy guest + * paging. + */ + pagefault_disable(); kvm_steal_time_set_preempted(vcpu); + pagefault_enable(); kvm_x86_ops->vcpu_put(vcpu); kvm_put_guest_fpu(vcpu); vcpu->arch.last_host_tsc = rdtsc(); -- 2.20.1