linux-kernel - [PATCH v6 03/10] s390: vfio-ap: allow hot plug/unplug of AP resources using mdev device

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Date:   Fri, 13 Sep 2019 17:26:51 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     freude@...ux.ibm.com, borntraeger@...ibm.com, cohuck@...hat.com,
        mjrosato@...ux.ibm.com, pmorel@...ux.ibm.com, pasic@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        jjherne@...ux.ibm.com, Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: [PATCH v6 03/10] s390: vfio-ap: allow hot plug/unplug of AP resources using mdev device

Let's allow AP resources - i.e., adapters, domains and control domains -
to be assigned to or unassigned from an AP matrix mdev while it is in use
by a guest. If an AP resource is assigned while a guest is using the
matrix mdev, the guest's CRYCB will be dynamically updated as follows:

* When assigning an adapter or domain, each APQN that is derived from the
  Cartesian product of the adapter numbers (APID) and domain numbers
  (APQI) assigned must reference an AP queue device that is bound to the
  vfio_ap device driver. If a particular APQN does not reference a queue
  bound to vfio_ap, the bits corresponding to the APID and APQI will not
  be set in the guest's CRYCB.

* When assigning a control domain, the bit corresponding to the domain
  number of the control domain will be set in the guest's CRYCB.

Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c | 24 ------------------------
 1 file changed, 24 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 18da9ab2b2fb..18270f286dec 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -511,10 +511,6 @@ static ssize_t assign_adapter_store(struct device *dev,
 	struct mdev_device *mdev = mdev_from_dev(dev);
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
-	/* If the guest is running, disallow assignment of adapter */
-	if (matrix_mdev->kvm)
-		return -EBUSY;
-
 	ret = kstrtoul(buf, 0, &apid);
 	if (ret)
 		return ret;
@@ -565,10 +561,6 @@ static ssize_t unassign_adapter_store(struct device *dev,
 	struct mdev_device *mdev = mdev_from_dev(dev);
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
-	/* If the guest is running, disallow un-assignment of adapter */
-	if (matrix_mdev->kvm)
-		return -EBUSY;
-
 	ret = kstrtoul(buf, 0, &apid);
 	if (ret)
 		return ret;
@@ -627,10 +619,6 @@ static ssize_t assign_domain_store(struct device *dev,
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
 
-	/* If the guest is running, disallow assignment of domain */
-	if (matrix_mdev->kvm)
-		return -EBUSY;
-
 	ret = kstrtoul(buf, 0, &apqi);
 	if (ret)
 		return ret;
@@ -681,10 +669,6 @@ static ssize_t unassign_domain_store(struct device *dev,
 	struct mdev_device *mdev = mdev_from_dev(dev);
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
-	/* If the guest is running, disallow un-assignment of domain */
-	if (matrix_mdev->kvm)
-		return -EBUSY;
-
 	ret = kstrtoul(buf, 0, &apqi);
 	if (ret)
 		return ret;
@@ -725,10 +709,6 @@ static ssize_t assign_control_domain_store(struct device *dev,
 	struct mdev_device *mdev = mdev_from_dev(dev);
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
-	/* If the guest is running, disallow assignment of control domain */
-	if (matrix_mdev->kvm)
-		return -EBUSY;
-
 	ret = kstrtoul(buf, 0, &id);
 	if (ret)
 		return ret;
@@ -770,10 +750,6 @@ static ssize_t unassign_control_domain_store(struct device *dev,
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 	unsigned long max_domid =  matrix_mdev->matrix.adm_max;
 
-	/* If the guest is running, disallow un-assignment of control domain */
-	if (matrix_mdev->kvm)
-		return -EBUSY;
-
 	ret = kstrtoul(buf, 0, &domid);
 	if (ret)
 		return ret;
-- 
2.7.4