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authorAndrea Arcangeli <aarcange@redhat.com>2016-12-17 20:43:52 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2016-12-19 17:45:14 +0300
commit931f261b42f10c8c8c9ab53f5ceb47ce51af7cf5 (patch)
tree1c9dd7e4ee202ecb6d7aef52c4e25c8d2a0c3f76 /arch
parent3f5ad8be3713572f3946b69eb376206153d0ea2d (diff)
downloadlinux-931f261b42f10c8c8c9ab53f5ceb47ce51af7cf5.tar.xz
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 <aarcange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/x86.c10
1 files changed, 10 insertions, 0 deletions
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();