From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: [PATCH] virtio-ccw: diag 500 may return a negative cookie Date: Tue, 18 Dec 2018 14:20:34 +0100 Message-ID: <20181218132034.14863-1-cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Halil Pasic Cc: linux-s390@vger.kernel.org, Cornelia Huck , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org If something goes wrong in the kvm io bus handling, the virtio-ccw diagnose may return a negative error value in the cookie gpr. Document this. Signed-off-by: Cornelia Huck --- Even if the virtio spec is the correct place to specify what diag 500 subcode 3 does, we also should mention here that the cookie may be an error. --- Documentation/virtual/kvm/s390-diag.txt | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Documentation/virtual/kvm/s390-diag.txt b/Documentation/virtual/kvm/s390-diag.txt index 48c4921794ed..7c52e5f8b210 100644 --- a/Documentation/virtual/kvm/s390-diag.txt +++ b/Documentation/virtual/kvm/s390-diag.txt @@ -68,7 +68,8 @@ Subcode 3 - virtio-ccw notification identifier, it is ignored. After completion of the DIAGNOSE call, general register 2 may contain - a 64bit identifier (in the kvm_io_bus cookie case). + a 64bit identifier (in the kvm_io_bus cookie case), or a negative + error value, if an internal error occurred. See also the virtio standard for a discussion of this hypercall. -- 2.17.2