Re: [PATCH v2 4/7] s390: vfio-ap: allow assignment of unavailable AP resources to mdev device

From: Pierre Morel
Date: Mon May 06 2019 - 03:05:53 EST

On 03/05/2019 23:14, Tony Krowiak wrote:
The AP architecture does not preclude assignment of AP resources that are
not yet in the AP configuration (i.e., not available or not online).
Let's go ahead and implement this facet of the AP architecture for linux
guests.

The current implementation does not allow assignment of AP resources to
an mdev device if the AP queue devices identified by the assignment are
not bound to the vfio_ap device driver. This patch allows assignment of AP
resources to the mdev device even if the AP queue devices are not bound to
the vfio_ap device driver, as long as the AP queue devices are not
reserved by the AP BUS for use by the zcrypt device drivers.

or another mediated device.



Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
---
drivers/s390/crypto/vfio_ap_ops.c | 231 ++++++++------------------------------
1 file changed, 44 insertions(+), 187 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 1021466cb661..ea24caf17a16 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -113,122 +113,6 @@ static struct attribute_group *vfio_ap_mdev_type_groups[] = {
NULL,
};
-struct vfio_ap_queue_reserved {
- unsigned long *apid;
- unsigned long *apqi;
- bool reserved;
-};
-
-/**
- * vfio_ap_has_queue
- *
- * @dev: an AP queue device
- * @data: a struct vfio_ap_queue_reserved reference
- *
- * Flags whether the AP queue device (@dev) has a queue ID containing the APQN,
- * apid or apqi specified in @data:
- *
- * - If @data contains both an apid and apqi value, then @data will be flagged
- * as reserved if the APID and APQI fields for the AP queue device matches
- *
- * - If @data contains only an apid value, @data will be flagged as
- * reserved if the APID field in the AP queue device matches
- *
- * - If @data contains only an apqi value, @data will be flagged as
- * reserved if the APQI field in the AP queue device matches
- *
- * Returns 0 to indicate the input to function succeeded. Returns -EINVAL if
- * @data does not contain either an apid or apqi.
- */
-static int vfio_ap_has_queue(struct device *dev, void *data)
-{
- struct vfio_ap_queue_reserved *qres = data;
- struct ap_queue *ap_queue = to_ap_queue(dev);
- ap_qid_t qid;
- unsigned long id;
-
- if (qres->apid && qres->apqi) {
- qid = AP_MKQID(*qres->apid, *qres->apqi);
- if (qid == ap_queue->qid)
- qres->reserved = true;
- } else if (qres->apid && !qres->apqi) {
- id = AP_QID_CARD(ap_queue->qid);
- if (id == *qres->apid)
- qres->reserved = true;
- } else if (!qres->apid && qres->apqi) {
- id = AP_QID_QUEUE(ap_queue->qid);
- if (id == *qres->apqi)
- qres->reserved = true;
- } else {
- return -EINVAL;
- }
-
- return 0;
-}
-
-/**
- * vfio_ap_verify_queue_reserved
- *
- * @matrix_dev: a mediated matrix device
- * @apid: an AP adapter ID
- * @apqi: an AP queue index
- *
- * Verifies that the AP queue with @apid/@apqi is reserved by the VFIO AP device
- * driver according to the following rules:
- *
- * - If both @apid and @apqi are not NULL, then there must be an AP queue
- * device bound to the vfio_ap driver with the APQN identified by @apid and
- * @apqi
- *
- * - If only @apid is not NULL, then there must be an AP queue device bound
- * to the vfio_ap driver with an APQN containing @apid
- *
- * - If only @apqi is not NULL, then there must be an AP queue device bound
- * to the vfio_ap driver with an APQN containing @apqi
- *
- * Returns 0 if the AP queue is reserved; otherwise, returns -EADDRNOTAVAIL.
- */
-static int vfio_ap_verify_queue_reserved(unsigned long *apid,
- unsigned long *apqi)
-{
- int ret;
- struct vfio_ap_queue_reserved qres;
-
- qres.apid = apid;
- qres.apqi = apqi;
- qres.reserved = false;
-
- ret = driver_for_each_device(&matrix_dev->vfio_ap_drv->driver, NULL,
- &qres, vfio_ap_has_queue);
- if (ret)
- return ret;
-
- if (qres.reserved)
- return 0;
-
- return -EADDRNOTAVAIL;
-}
-
-static int
-vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev,
- unsigned long apid)
-{
- int ret;
- unsigned long apqi;
- unsigned long nbits = matrix_mdev->matrix.aqm_max + 1;
-
- if (find_first_bit_inv(matrix_mdev->matrix.aqm, nbits) >= nbits)
- return vfio_ap_verify_queue_reserved(&apid, NULL);
-
- for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, nbits) {
- ret = vfio_ap_verify_queue_reserved(&apid, &apqi);
- if (ret)
- return ret;
- }
-
- return 0;
-}
-
/**
* vfio_ap_mdev_verify_no_sharing
*
@@ -236,18 +120,26 @@ vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev,
* and AP queue indexes comprising the AP matrix are not configured for another
* mediated device. AP queue sharing is not allowed.
*
- * @matrix_mdev: the mediated matrix device
+ * @mdev_apm: the mask identifying the adapters assigned to mdev
+ * @mdev_apm: the mask identifying the adapters assigned to mdev
*
* Returns 0 if the APQNs are not shared, otherwise; returns -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;
DECLARE_BITMAP(apm, AP_DEVICES);
DECLARE_BITMAP(aqm, AP_DOMAINS);
list_for_each_entry(lstdev, &matrix_dev->mdev_list, node) {
- if (matrix_mdev == lstdev)
+ /*
+ * If either of the input masks belongs to the mdev to which an
+ * AP resource is being assigned, then we don't need to verify
+ * that mdev's masks.
+ */
+ if ((mdev_apm == lstdev->matrix.apm) ||
+ (mdev_aqm == lstdev->matrix.aqm))
continue;

Is it possible that mdev_apm and mdev_aqm do not belong to the same mediated device?

...snip...


--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany