[PATCH v6 16/21] vfio-pci/zdev: add open/close device hooks

[Matthew Rosato <mjrosato@linux.ibm.com>]

During vfio-pci open_device, register a notifier for the zPCI device to
catch KVM registration.  This is needed in order to pass a special
indicator (GISA) to firmware to allow zPCI interpretation facilities to be
used for only the specific KVM associated with the vfio-pci device.
During vfio-pci close_device, unregister the notifier.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
 arch/s390/include/asm/pci.h      |  2 ++
 drivers/vfio/pci/vfio_pci_core.c |  2 ++
 drivers/vfio/pci/vfio_pci_zdev.c | 50 ++++++++++++++++++++++++++++++++
 include/linux/vfio_pci_core.h    | 10 +++++++
 4 files changed, 64 insertions(+)

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 322060a75d9f..fdcc95b36edb 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -5,6 +5,7 @@
 #include <linux/pci.h>
 #include <linux/mutex.h>
 #include <linux/iommu.h>
+#include <linux/notifier.h>
 #include <linux/pci_hotplug.h>
 #include <asm-generic/pci.h>
 #include <asm/pci_clp.h>
@@ -194,6 +195,7 @@ struct zpci_dev {
 	/* IOMMU and passthrough */
 	struct s390_domain *s390_domain; /* s390 IOMMU domain data */
 	struct kvm_zdev *kzdev;
+	struct notifier_block nb; /* vfio notifications */
 };
 
 static inline bool zdev_enabled(struct zpci_dev *zdev)
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 06b6f3594a13..d53125b308f0 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -449,6 +449,7 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev)
 		vdev->sriov_pf_core_dev->vf_token->users--;
 		mutex_unlock(&vdev->sriov_pf_core_dev->vf_token->lock);
 	}
+	vfio_pci_zdev_release(vdev);
 	vfio_spapr_pci_eeh_release(vdev->pdev);
 	vfio_pci_core_disable(vdev);
 
@@ -469,6 +470,7 @@ void vfio_pci_core_finish_enable(struct vfio_pci_core_device *vdev)
 {
 	vfio_pci_probe_mmaps(vdev);
 	vfio_spapr_pci_eeh_open(vdev->pdev);
+	vfio_pci_zdev_open(vdev);
 
 	if (vdev->sriov_pf_core_dev) {
 		mutex_lock(&vdev->sriov_pf_core_dev->vf_token->lock);
diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index ea4c0d2b0663..112c1f820f8e 100644
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -11,6 +11,7 @@
 #include <linux/uaccess.h>
 #include <linux/vfio.h>
 #include <linux/vfio_zdev.h>
+#include <linux/kvm_host.h>
 #include <asm/pci_clp.h>
 #include <asm/pci_io.h>
 
@@ -136,3 +137,52 @@ int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
 
 	return ret;
 }
+
+static int vfio_pci_zdev_group_notifier(struct notifier_block *nb,
+					unsigned long action, void *data)
+{
+	struct zpci_dev *zdev = container_of(nb, struct zpci_dev, nb);
+	int (*fn)(struct zpci_dev *zdev, struct kvm *kvm);
+	int rc = NOTIFY_OK;
+
+	if (action == VFIO_GROUP_NOTIFY_SET_KVM) {
+		if (!zdev)
+			return NOTIFY_DONE;
+
+		fn = symbol_get(kvm_s390_pci_register_kvm);
+		if (!fn)
+			return NOTIFY_DONE;
+
+		if (fn(zdev, (struct kvm *)data))
+			rc = NOTIFY_BAD;
+
+		symbol_put(kvm_s390_pci_register_kvm);
+	}
+
+	return rc;
+}
+
+void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
+{
+	unsigned long events = VFIO_GROUP_NOTIFY_SET_KVM;
+	struct zpci_dev *zdev = to_zpci(vdev->pdev);
+
+	if (!zdev)
+		return;
+
+	zdev->nb.notifier_call = vfio_pci_zdev_group_notifier;
+
+	vfio_register_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
+			       &events, &zdev->nb);
+}
+
+void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
+{
+	struct zpci_dev *zdev = to_zpci(vdev->pdev);
+
+	if (!zdev)
+		return;
+
+	vfio_unregister_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
+				 &zdev->nb);
+}
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 48f2dd3c568c..b1b285421c18 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -209,12 +209,22 @@ static inline int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
 #ifdef CONFIG_S390
 extern int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
 				       struct vfio_info_cap *caps);
+void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev);
+void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev);
 #else
 static inline int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
 					      struct vfio_info_cap *caps)
 {
 	return -ENODEV;
 }
+
+static inline void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
+{
+}
+
+static inline void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
+{
+}
 #endif
 
 /* Will be exported for vfio pci drivers usage */
-- 
2.27.0