[PATCH v16 08/14] s390/vfio-ap: allow hot plug/unplug of AP resources using mdev device

[Tony Krowiak <akrowiak@linux.ibm.com>]

Let's allow adapters, domains and control domains to be hot plugged into
and hot unplugged from a KVM guest using a matrix mdev when:

* The adapter, domain or control domain is assigned to or unassigned from
  the matrix mdev

* A queue device with an APQN assigned to the matrix mdev is bound to or
  unbound from the vfio_ap device driver.

Whenever an assignment or unassignment of an adapter, domain or control
domain is performed as well as when a bind or unbind of a queue device
is executed, the AP control block (APCB) that supplies the AP configuration
to the guest is first refreshed.

After refreshing the APCB, if the mdev is in use by a KVM guest, it is
hot plugged into the guest to provide access to dynamically provide
access to the adapters, domains and control domains provided via the
newly refreshed APCB.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c | 91 ++++++++++++++++++++++++-------
 1 file changed, 71 insertions(+), 20 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 6486245aa89a..e388eaf4f601 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -24,7 +24,7 @@
 #define VFIO_AP_MDEV_TYPE_HWVIRT "passthrough"
 #define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"
 
-static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
+static int vfio_ap_mdev_reset_queues(struct ap_matrix *matrix);
 static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
 
 static struct vfio_ap_queue *
@@ -262,8 +262,8 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
 	if (!(vcpu->arch.sie_block->eca & ECA_AIV))
 		return -EOPNOTSUPP;
 
-	apqn = vcpu->run->s.regs.gprs[0] & 0xffff;
 	mutex_lock(&matrix_dev->lock);
+	apqn = vcpu->run->s.regs.gprs[0] & 0xffff;
 
 	if (!vcpu->kvm->arch.crypto.pqap_hook)
 		goto out_unlock;
@@ -336,6 +336,31 @@ static void vfio_ap_mdev_clear_apcb(struct ap_matrix_mdev *matrix_mdev)
 		wake_up_all(&matrix_mdev->wait_for_kvm);
 	}
 }
+
+static void vfio_ap_mdev_commit_apcb(struct ap_matrix_mdev *matrix_mdev)
+{
+	/*
+	 * If the KVM pointer is in the process of being set, wait until the
+	 * process has completed.
+	 */
+	wait_event_cmd(matrix_mdev->wait_for_kvm,
+		       !matrix_mdev->kvm_busy,
+		       mutex_unlock(&matrix_dev->lock),
+		       mutex_lock(&matrix_dev->lock));
+
+	if (vfio_ap_mdev_has_crycb(matrix_mdev)) {
+		matrix_mdev->kvm_busy = true;
+		mutex_unlock(&matrix_dev->lock);
+		kvm_arch_crypto_set_masks(matrix_mdev->kvm,
+					  matrix_mdev->shadow_apcb.apm,
+					  matrix_mdev->shadow_apcb.aqm,
+					  matrix_mdev->shadow_apcb.adm);
+		mutex_lock(&matrix_dev->lock);
+		matrix_mdev->kvm_busy = false;
+		wake_up_all(&matrix_mdev->wait_for_kvm);
+	}
+}
+
 /*
  * vfio_ap_mdev_filter_apcb
  *
@@ -403,6 +428,7 @@ static void vfio_ap_mdev_refresh_apcb(struct ap_matrix_mdev *matrix_mdev)
 		   sizeof(struct ap_matrix)) != 0) {
 		memcpy(&matrix_mdev->shadow_apcb, &shadow_apcb,
 		       sizeof(struct ap_matrix));
+		vfio_ap_mdev_commit_apcb(matrix_mdev);
 	}
 }
 
@@ -492,7 +518,7 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev)
 	WARN(vfio_ap_mdev_has_crycb(matrix_mdev),
 	     "Removing mdev leaves KVM guest without any crypto devices");
 	vfio_ap_mdev_clear_apcb(matrix_mdev);
-	vfio_ap_mdev_reset_queues(mdev);
+	vfio_ap_mdev_reset_queues(&matrix_mdev->matrix);
 	vfio_ap_mdev_unlink_fr_queues(matrix_mdev);
 	list_del(&matrix_mdev->node);
 	kfree(matrix_mdev);
@@ -682,7 +708,7 @@ static ssize_t assign_adapter_store(struct device *dev,
 	 * If the KVM pointer is in flux or the guest is running, disallow
 	 * un-assignment of adapter
 	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
+	if (matrix_mdev->kvm_busy) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -760,7 +786,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
 	 * If the KVM pointer is in flux or the guest is running, disallow
 	 * un-assignment of adapter
 	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
+	if (matrix_mdev->kvm_busy) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -841,7 +867,7 @@ static ssize_t assign_domain_store(struct device *dev,
 	 * If the KVM pointer is in flux or the guest is running, disallow
 	 * assignment of domain
 	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
+	if (matrix_mdev->kvm_busy) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -918,7 +944,7 @@ static ssize_t unassign_domain_store(struct device *dev,
 	 * If the KVM pointer is in flux or the guest is running, disallow
 	 * un-assignment of domain
 	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
+	if (matrix_mdev->kvm_busy) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -943,6 +969,16 @@ static ssize_t unassign_domain_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(unassign_domain);
 
+static void vfio_ap_mdev_hot_plug_cdom(struct ap_matrix_mdev *matrix_mdev,
+				       unsigned long domid)
+{
+	if (!test_bit_inv(domid, matrix_mdev->shadow_apcb.adm) &&
+	    test_bit_inv(domid, (unsigned long *)matrix_dev->info.adm)) {
+		set_bit_inv(domid, matrix_mdev->shadow_apcb.adm);
+		vfio_ap_mdev_commit_apcb(matrix_mdev);
+	}
+}
+
 /**
  * assign_control_domain_store
  *
@@ -974,7 +1010,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
 	 * If the KVM pointer is in flux or the guest is running, disallow
 	 * assignment of control domain.
 	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
+	if (matrix_mdev->kvm_busy) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -994,7 +1030,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
 	 * number of control domains that can be assigned.
 	 */
 	set_bit_inv(id, matrix_mdev->matrix.adm);
-	vfio_ap_mdev_refresh_apcb(matrix_mdev);
+	vfio_ap_mdev_hot_plug_cdom(matrix_mdev, id);
 	ret = count;
 done:
 	mutex_unlock(&matrix_dev->lock);
@@ -1002,6 +1038,15 @@ static ssize_t assign_control_domain_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(assign_control_domain);
 
+static void vfio_ap_mdev_hot_unplug_cdom(struct ap_matrix_mdev *matrix_mdev,
+					 unsigned long domid)
+{
+	if (test_bit_inv(domid, matrix_mdev->shadow_apcb.adm)) {
+		clear_bit_inv(domid, matrix_mdev->shadow_apcb.adm);
+		vfio_ap_mdev_commit_apcb(matrix_mdev);
+	}
+}
+
 /**
  * unassign_control_domain_store
  *
@@ -1034,7 +1079,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
 	 * If the KVM pointer is in flux or the guest is running, disallow
 	 * un-assignment of control domain.
 	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
+	if (matrix_mdev->kvm_busy) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -1048,7 +1093,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
 	}
 
 	clear_bit_inv(domid, matrix_mdev->matrix.adm);
-	vfio_ap_mdev_refresh_apcb(matrix_mdev);
+	vfio_ap_mdev_hot_unplug_cdom(matrix_mdev, domid);
 	ret = count;
 done:
 	mutex_unlock(&matrix_dev->lock);
@@ -1257,7 +1302,7 @@ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)
 		mutex_unlock(&matrix_dev->lock);
 		kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
 		mutex_lock(&matrix_dev->lock);
-		vfio_ap_mdev_reset_queues(matrix_mdev->mdev);
+		vfio_ap_mdev_reset_queues(&matrix_mdev->matrix);
 		matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
 		kvm_put_kvm(matrix_mdev->kvm);
 		matrix_mdev->kvm = NULL;
@@ -1356,18 +1401,15 @@ int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
 	return ret;
 }
 
-static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
+static int vfio_ap_mdev_reset_queues(struct ap_matrix *matrix)
 {
 	int ret;
 	int rc = 0;
 	unsigned long apid, apqi;
 	struct vfio_ap_queue *q;
-	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
-	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm,
-			     matrix_mdev->matrix.apm_max + 1) {
-		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
-				     matrix_mdev->matrix.aqm_max + 1) {
+	for_each_set_bit_inv(apid, matrix->apm, AP_DEVICES) {
+		for_each_set_bit_inv(apqi, matrix->aqm, AP_DOMAINS) {
 			q = vfio_ap_find_queue(AP_MKQID(apid, apqi));
 			ret = vfio_ap_mdev_reset_queue(q, 1);
 			/*
@@ -1478,7 +1520,7 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
 			       mutex_unlock(&matrix_dev->lock),
 			       mutex_lock(&matrix_dev->lock));
 
-		ret = vfio_ap_mdev_reset_queues(mdev);
+		ret = vfio_ap_mdev_reset_queues(&matrix_mdev->matrix);
 		break;
 	default:
 		ret = -EOPNOTSUPP;
@@ -1545,8 +1587,17 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 	q->apqn = to_ap_queue(&apdev->device)->qid;
 	q->saved_isc = VFIO_AP_ISC_INVALID;
 	vfio_ap_queue_link_mdev(q);
-	if (q->matrix_mdev)
+	if (q->matrix_mdev) {
+		/*
+		 * If the KVM pointer is in the process of being set, wait
+		 * until the process has completed.
+		 */
+		wait_event_cmd(q->matrix_mdev->wait_for_kvm,
+			       !q->matrix_mdev->kvm_busy,
+			       mutex_unlock(&matrix_dev->lock),
+			       mutex_lock(&matrix_dev->lock));
 		vfio_ap_mdev_refresh_apcb(q->matrix_mdev);
+	}
 	dev_set_drvdata(&apdev->device, q);
 	mutex_unlock(&matrix_dev->lock);
 
-- 
2.30.2