[PATCH v3 24/30] vfio-pci/zdev: wire up group notifier

[Matthew Rosato <mjrosato@xxxxxxxxxxxxx>]

KVM zPCI passthrough device logic will need a reference to the associated
kvm guest that has access to the device.  Let's register a group notifier
for VFIO_GROUP_NOTIFY_SET_KVM to catch this information in order to create
an association between a kvm guest and the host zdev.

Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_pci.h  |  2 ++
 drivers/vfio/pci/vfio_pci_core.c |  2 ++
 drivers/vfio/pci/vfio_pci_zdev.c | 46 ++++++++++++++++++++++++++++++++
 include/linux/vfio_pci_core.h    | 10 +++++++
 4 files changed, 60 insertions(+)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index e4696f5592e1..16290b4cf2a6 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -16,6 +16,7 @@
 #include <linux/kvm.h>
 #include <linux/pci.h>
 #include <linux/mutex.h>
+#include <linux/notifier.h>
 #include <asm/pci_insn.h>
 #include <asm/pci_dma.h>
 
@@ -32,6 +33,7 @@ struct kvm_zdev {
 	u64 rpcit_count;
 	struct kvm_zdev_ioat ioat;
 	struct zpci_fib fib;
+	struct notifier_block nb;
 };
 
 int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index f948e6cd2993..fc57d4d0abbe 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -452,6 +452,7 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev)
 
 	vfio_pci_vf_token_user_add(vdev, -1);
 	vfio_spapr_pci_eeh_release(vdev->pdev);
+	vfio_pci_zdev_release(vdev);
 	vfio_pci_core_disable(vdev);
 
 	mutex_lock(&vdev->igate);
@@ -470,6 +471,7 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_close_device);
 void vfio_pci_core_finish_enable(struct vfio_pci_core_device *vdev)
 {
 	vfio_pci_probe_mmaps(vdev);
+	vfio_pci_zdev_open(vdev);
 	vfio_spapr_pci_eeh_open(vdev->pdev);
 	vfio_pci_vf_token_user_add(vdev, 1);
 }
diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index ea4c0d2b0663..9f8284499111 100644
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -13,6 +13,7 @@
 #include <linux/vfio_zdev.h>
 #include <asm/pci_clp.h>
 #include <asm/pci_io.h>
+#include <asm/kvm_pci.h>
 
 #include <linux/vfio_pci_core.h>
 
@@ -136,3 +137,48 @@ 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 kvm_zdev *kzdev = container_of(nb, struct kvm_zdev, nb);
+
+	if (action == VFIO_GROUP_NOTIFY_SET_KVM) {
+		if (!data || !kzdev->zdev)
+			return NOTIFY_DONE;
+		kzdev->kvm = data;
+	}
+
+	return NOTIFY_OK;
+}
+
+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;
+
+	if (kvm_s390_pci_dev_open(zdev))
+		return;
+
+	zdev->kzdev->nb.notifier_call = vfio_pci_zdev_group_notifier;
+
+	if (vfio_register_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
+				   &events, &zdev->kzdev->nb))
+		kvm_s390_pci_dev_release(zdev);
+}
+
+void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
+{
+	struct zpci_dev *zdev = to_zpci(vdev->pdev);
+
+	if (!zdev || !zdev->kzdev)
+		return;
+
+	vfio_unregister_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
+				 &zdev->kzdev->nb);
+
+	kvm_s390_pci_dev_release(zdev);
+}
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 5e2bca3b89db..05287f8ac855 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -198,12 +198,22 @@ static inline int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
 #ifdef CONFIG_VFIO_PCI_ZDEV
 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