On 3/7/22 08:27, Halil Pasic wrote:
On Mon, 7 Mar 2022 07:31:21 -0500
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
On 3/3/22 10:39, Jason J. Herne wrote:
On 2/14/22 19:50, Tony Krowiak wrote:
/**
- * vfio_ap_mdev_verify_no_sharing - verifies that the AP matrix is
not configured
+ * vfio_ap_mdev_verify_no_sharing - verify APQNs are not shared by
matrix mdevs
*
- * @matrix_mdev: the mediated matrix device
+ * @mdev_apm: mask indicating the APIDs of the APQNs to be verified
+ * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified
*
- * Verifies that the APQNs derived from the cross product of the AP
adapter IDs
- * and AP queue indexes comprising the AP matrix are not configured
for another
+ * Verifies that each APQN derived from the Cartesian product of a
bitmap of
+ * AP adapter IDs and AP queue indexes is not configured for any matrix
* mediated device. AP queue sharing is not allowed.
*
- * Return: 0 if the APQNs are not shared; otherwise returns
-EADDRINUSE.
+ * Return: 0 if the APQNs are not shared; otherwise return -EADDRINUSE.
*/
-static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev
*matrix_mdev)
+static int vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
+ unsigned long *mdev_aqm)
{
- struct ap_matrix_mdev *lstdev;
+ struct ap_matrix_mdev *matrix_mdev;
DECLARE_BITMAP(apm, AP_DEVICES);
DECLARE_BITMAP(aqm, AP_DOMAINS);
- list_for_each_entry(lstdev, &matrix_dev->mdev_list, node) {
- if (matrix_mdev == lstdev)
+ list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
+ /*
+ * If the input apm and aqm belong to the matrix_mdev's matrix,
How about:
s/belong to the matrix_mdev's matrix/are fields of the matrix_mdev
object/
This is the comment I wrote:
/*
* Comparing an mdev's newly updated apm/aqm with itself would
* result in a false positive when verifying whether any APQNs
* are shared; so, if the input apm and aqm belong to the
* matrix_mdev's matrix, then move on to the next one.
*/
However, I'd be happy to change it to whatever either of you want.
+ * then move on to the next.
+ */
+ if (mdev_apm == matrix_mdev->matrix.apm &&
+ mdev_aqm == matrix_mdev->matrix.aqm)
continue;
We may have a problem here. This check seems like it exists to stop
you from
comparing an mdev's apm/aqm with itself. Obviously comparing an mdev's
newly
updated apm/aqm with itself would cause a false positive sharing
check, right?
If this is the case, I think the comment should be changed to reflect
that.
You are correct, this check is performed to prevent comparing an mdev to
itself, I'll improve the comment.
Aside from the comment, what stops this particular series of if
statements from
allowing us to configure a second mdev with the exact same apm/aqm
values as an
existing mdev? If we do, then this check's continue will short circuit
the rest
of the function thereby allowing that 2nd mdev even though it should be a
sharing violation.
I don't see how this is possible.
I agree with Tony and his explanation.
Furthermore IMHO is relates to the class identity vs equality problem, in
a sense that identity always implies equality.
Regards,
Halil
