[1/3] virtio-ccw: diag 500 may return a negative cookie
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Message ID 20190121121944.12309-2-cohuck@redhat.com
State New
Headers show
  • virtio-ccw: updates
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Commit Message

Cornelia Huck Jan. 21, 2019, 12:19 p.m. UTC
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.

Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
 Documentation/virtual/kvm/s390-diag.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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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.