On 07/30/2018 01:28 PM, Cornelia Huck wrote:
On Mon, 30 Jul 2018 13:24:24 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
On 30/07/2018 11:49, Cornelia Huck wrote:
On Fri, 27 Jul 2018 16:17:47 +0200
Halil Pasic <pasic@xxxxxxxxxxxxx> wrote:
On 07/26/2018 09:54 PM, Christian Borntraeger wrote:
@@ -65,6 +66,21 @@ static int vfio_ap_matrix_dev_create(void)
{
int ret;
+ mutex_init(&matrix_dev.lock);
+ INIT_LIST_HEAD(&matrix_dev.mdev_list);
+
+ /* Test if PQAP(QCI) instruction is available */
+ if (test_facility(12)) {
+ ret = ap_qci(&matrix_dev.info);
+ if (ret && (ret != -EOPNOTSUPP)) {
After Connie's curiosity was piqued I gave this another look. If
I read the ap_qci() documentation and code correctly, it can return
either 0 or -EOPNOTSUPP, but nothing else. So basically this
is a dead branch.
Can it return -EOPNOTSUPP if facility 12 is present?
I do not think it is reasonable to continue if
we stated that facility 12 is present but the ap_qci function failed.
So I propose that we return an error and break the insmod.
So, would that be a bug? If yes, returning an error makes sense.
(I can't check the documentation to find out about the interaction
between facility 12 and PQAP(QCI)...)
If we are in z architectural mode and facility 12 is indicated and
ap_qci() returns an error code, it's because of an exception while
executing the PQAP instruction. The reason can be a bad input pointer
or other stuff. It is likely a bug. I'm not sure how this interacts
with machine checks though. I think we should report the problem
and give up.
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