Commit c9d61dcb authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: SEV: accept signals in sev_lock_two_vms 



Generally, kvm->lock is not taken for a long time, but
sev_lock_two_vms is different: it takes vCPU locks
inside, so userspace can hold it back just by calling
a vCPU ioctl.  Play it safe and use mutex_lock_killable.

Message-Id: <20211123005036.2954379-13-pbonzini@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 10a37929

arch/x86/kvm/svm/sev.c

+16 −6
Original line number Diff line number Diff line
@@ -1547,6 +1547,7 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) 
{

	struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info;

	struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info;

	int r = -EBUSY;



	if (dst_kvm == src_kvm)

		return -EINVAL;
@@ -1558,14 +1559,23 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) 
	if (atomic_cmpxchg_acquire(&dst_sev->migration_in_progress, 0, 1))

		return -EBUSY;



	if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1)) {

		atomic_set_release(&dst_sev->migration_in_progress, 0);

		return -EBUSY;

	}

	if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1))

		goto release_dst;



	mutex_lock(&dst_kvm->lock);

	mutex_lock(&src_kvm->lock);

	r = -EINTR;

	if (mutex_lock_killable(&dst_kvm->lock))

		goto release_src;

	if (mutex_lock_killable(&src_kvm->lock))

		goto unlock_dst;

	return 0;



unlock_dst:

	mutex_unlock(&dst_kvm->lock);

release_src:

	atomic_set_release(&src_sev->migration_in_progress, 0);

release_dst:

	atomic_set_release(&dst_sev->migration_in_progress, 0);

	return r;

}



static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)