diff mbox series

[v2,2/2] s390/vfio-ap: reverse group notifier actions when KVM pointer invalidated

Message ID 20201211222211.20869-3-akrowiak@linux.ibm.com
State New
Headers show
Series Clean up vfio_ap resources when KVM pointer invalidated | expand

Commit Message

Anthony Krowiak Dec. 11, 2020, 10:22 p.m. UTC 
The vfio_ap device driver registers a group notifier with VFIO when the
file descriptor for a VFIO mediated device for a KVM guest is opened to
receive notification that the KVM pointer is set (VFIO_GROUP_NOTIFY_SET_KVM
event). When the KVM pointer is set, the vfio_ap driver takes the
following actions:
1. Stashes the KVM pointer in the vfio_ap_mdev struct that holds the state
   of the mediated device.
2. Calls the kvm_get_kvm() function to increment its reference counter.
3. Sets the function pointer to the function that handles interception of
   the instruction that enables/disables interrupt processing.

When the notifier is called to make notification that the KVM pointer has
been set to NULL, the driver should reverse the actions taken when the
KVM pointer was set as well as unplugging the AP devices passed through
to the KVM guest.

Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback")
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c | 40 ++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 16 deletions(-)

Comments

Greg Kroah-Hartman Dec. 12, 2020, 8:20 a.m. UTC | #1 
On Fri, Dec 11, 2020 at 05:22:11PM -0500, Tony Krowiak wrote:
> The vfio_ap device driver registers a group notifier with VFIO when the

> file descriptor for a VFIO mediated device for a KVM guest is opened to

> receive notification that the KVM pointer is set (VFIO_GROUP_NOTIFY_SET_KVM

> event). When the KVM pointer is set, the vfio_ap driver takes the

> following actions:

> 1. Stashes the KVM pointer in the vfio_ap_mdev struct that holds the state

>    of the mediated device.

> 2. Calls the kvm_get_kvm() function to increment its reference counter.

> 3. Sets the function pointer to the function that handles interception of

>    the instruction that enables/disables interrupt processing.

> 

> When the notifier is called to make notification that the KVM pointer has

> been set to NULL, the driver should reverse the actions taken when the

> KVM pointer was set as well as unplugging the AP devices passed through

> to the KVM guest.

> 

> Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback")

> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>

> ---

>  drivers/s390/crypto/vfio_ap_ops.c | 40 ++++++++++++++++++-------------

>  1 file changed, 24 insertions(+), 16 deletions(-)


<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>
diff mbox series

Patch

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index c854d7ab2079..1c3c2a0898b9 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1033,8 +1033,6 @@  static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
 {
 	struct ap_matrix_mdev *m;
 
-	mutex_lock(&matrix_dev->lock);
-
 	list_for_each_entry(m, &matrix_dev->mdev_list, node) {
 		if ((m != matrix_mdev) && (m->kvm == kvm)) {
 			mutex_unlock(&matrix_dev->lock);
@@ -1045,7 +1043,6 @@  static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
 	matrix_mdev->kvm = kvm;
 	kvm_get_kvm(kvm);
 	kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook;
-	mutex_unlock(&matrix_dev->lock);
 
 	return 0;
 }
@@ -1079,35 +1076,49 @@  static int vfio_ap_mdev_iommu_notifier(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
+static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)
+{
+	kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
+	matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
+	vfio_ap_mdev_reset_queues(matrix_mdev->mdev);
+	kvm_put_kvm(matrix_mdev->kvm);
+	matrix_mdev->kvm = NULL;
+}
+
 static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
 				       unsigned long action, void *data)
 {
-	int ret;
+	int ret, notify_rc = NOTIFY_DONE;
 	struct ap_matrix_mdev *matrix_mdev;
 
 	if (action != VFIO_GROUP_NOTIFY_SET_KVM)
 		return NOTIFY_OK;
 
 	matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier);
+	mutex_lock(&matrix_dev->lock);
 
 	if (!data) {
-		matrix_mdev->kvm = NULL;
-		return NOTIFY_OK;
+		if (matrix_mdev->kvm)
+			vfio_ap_mdev_unset_kvm(matrix_mdev);
+		notify_rc = NOTIFY_OK;
+		goto notify_done;
 	}
 
 	ret = vfio_ap_mdev_set_kvm(matrix_mdev, data);
 	if (ret)
-		return NOTIFY_DONE;
+		goto notify_done;
 
 	/* If there is no CRYCB pointer, then we can't copy the masks */
 	if (!matrix_mdev->kvm->arch.crypto.crycbd)
-		return NOTIFY_DONE;
+		goto notify_done;
 
 	kvm_arch_crypto_set_masks(matrix_mdev->kvm, matrix_mdev->matrix.apm,
 				  matrix_mdev->matrix.aqm,
 				  matrix_mdev->matrix.adm);
 
-	return NOTIFY_OK;
+notify_done:
+	mutex_unlock(&matrix_dev->lock);
+	return notify_rc;
 }
 
 static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
@@ -1234,13 +1245,10 @@  static void vfio_ap_mdev_release(struct mdev_device *mdev)
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
 	mutex_lock(&matrix_dev->lock);
-	if (matrix_mdev->kvm) {
-		kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
-		matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
-		vfio_ap_mdev_reset_queues(mdev);
-		kvm_put_kvm(matrix_mdev->kvm);
-		matrix_mdev->kvm = NULL;
-	}
+	if (matrix_mdev->kvm)
+		vfio_ap_mdev_unset_kvm(matrix_mdev);
+	else
+		vfio_ap_mdev_reset_queues(matrix_mdev->mdev);
 	mutex_unlock(&matrix_dev->lock);
 
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,