netdev - [PATCH RFC v2 virtio 6/7] pds_vdpa: subscribe to the pds

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Date:   Wed, 8 Mar 2023 17:30:45 -0800
From:   Shannon Nelson <shannon.nelson@....com>
To:     <jasowang@...hat.com>, <mst@...hat.com>,
        <virtualization@...ts.linux-foundation.org>,
        <shannon.nelson@....com>, <brett.creeley@....com>,
        <davem@...emloft.net>, <netdev@...r.kernel.org>, <kuba@...nel.org>
CC:     <drivers@...sando.io>
Subject: [PATCH RFC v2 virtio 6/7] pds_vdpa: subscribe to the pds_core events

Register for the pds_core's notification events, primarily to
find out when the FW has been reset so we can pass this on
back up the chain.

Signed-off-by: Shannon Nelson <shannon.nelson@....com>
---
 drivers/vdpa/pds/vdpa_dev.c | 68 ++++++++++++++++++++++++++++++++++++-
 drivers/vdpa/pds/vdpa_dev.h |  1 +
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/pds/vdpa_dev.c b/drivers/vdpa/pds/vdpa_dev.c
index 2e0a5078d379..d99adb4f9fb1 100644
--- a/drivers/vdpa/pds/vdpa_dev.c
+++ b/drivers/vdpa/pds/vdpa_dev.c
@@ -22,6 +22,61 @@ static struct pds_vdpa_device *vdpa_to_pdsv(struct vdpa_device *vdpa_dev)
 	return container_of(vdpa_dev, struct pds_vdpa_device, vdpa_dev);
 }
 
+static int pds_vdpa_notify_handler(struct notifier_block *nb,
+				   unsigned long ecode,
+				   void *data)
+{
+	struct pds_vdpa_device *pdsv = container_of(nb, struct pds_vdpa_device, nb);
+	struct device *dev = pdsv->vdpa_aux->padev->vf->dev;
+
+	dev_dbg(dev, "%s: event code %lu\n", __func__, ecode);
+
+	/* Give the upper layers a hint that something interesting
+	 * may have happened.  It seems that the only thing this
+	 * triggers in the virtio-net drivers above us is a check
+	 * of link status.
+	 *
+	 * We don't set the NEEDS_RESET flag for EVENT_RESET
+	 * because we're likely going through a recovery or
+	 * fw_update and will be back up and running soon.
+	 */
+	if (ecode == PDS_EVENT_RESET || ecode == PDS_EVENT_LINK_CHANGE) {
+		if (pdsv->config_cb.callback)
+			pdsv->config_cb.callback(pdsv->config_cb.private);
+	}
+
+	return 0;
+}
+
+static int pds_vdpa_register_event_handler(struct pds_vdpa_device *pdsv)
+{
+	struct device *dev = pdsv->vdpa_aux->padev->vf->dev;
+	struct notifier_block *nb = &pdsv->nb;
+	int err;
+
+	if (!nb->notifier_call) {
+		nb->notifier_call = pds_vdpa_notify_handler;
+		err = pdsc_register_notify(nb);
+		if (err) {
+			nb->notifier_call = NULL;
+			dev_err(dev, "failed to register pds event handler: %ps\n",
+				ERR_PTR(err));
+			return -EINVAL;
+		}
+		dev_dbg(dev, "pds event handler registered\n");
+	}
+
+	return 0;
+}
+
+static void pds_vdpa_unregister_event_handler(struct pds_vdpa_device *pdsv)
+{
+	if (pdsv->nb.notifier_call) {
+		pdsc_unregister_notify(&pdsv->nb);
+		pdsv->nb.notifier_call = NULL;
+	}
+}
+
 static int pds_vdpa_set_vq_address(struct vdpa_device *vdpa_dev, u16 qid,
 				   u64 desc_addr, u64 driver_addr, u64 device_addr)
 {
@@ -538,6 +593,12 @@ static int pds_vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 
 	pdsv->vdpa_dev.mdev = &vdpa_aux->vdpa_mdev;
 
+	err = pds_vdpa_register_event_handler(pdsv);
+	if (err) {
+		dev_err(dev, "Failed to register for PDS events: %pe\n", ERR_PTR(err));
+		goto err_unmap;
+	}
+
 	/* We use the _vdpa_register_device() call rather than the
 	 * vdpa_register_device() to avoid a deadlock because our
 	 * dev_add() is called with the vdpa_dev_lock already set
@@ -546,13 +607,15 @@ static int pds_vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 	err = _vdpa_register_device(&pdsv->vdpa_dev, pdsv->num_vqs);
 	if (err) {
 		dev_err(dev, "Failed to register to vDPA bus: %pe\n", ERR_PTR(err));
-		goto err_unmap;
+		goto err_unevent;
 	}
 
 	pds_vdpa_debugfs_add_vdpadev(vdpa_aux);
 
 	return 0;
 
+err_unevent:
+	pds_vdpa_unregister_event_handler(pdsv);
 err_unmap:
 	put_device(&pdsv->vdpa_dev.dev);
 	vdpa_aux->pdsv = NULL;
@@ -562,8 +625,11 @@ static int pds_vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 static void pds_vdpa_dev_del(struct vdpa_mgmt_dev *mdev,
 			     struct vdpa_device *vdpa_dev)
 {
+	struct pds_vdpa_device *pdsv = vdpa_to_pdsv(vdpa_dev);
 	struct pds_vdpa_aux *vdpa_aux;
 
+	pds_vdpa_unregister_event_handler(pdsv);
+
 	vdpa_aux = container_of(mdev, struct pds_vdpa_aux, vdpa_mdev);
 	_vdpa_unregister_device(vdpa_dev);
 	pds_vdpa_debugfs_del_vdpadev(vdpa_aux);
diff --git a/drivers/vdpa/pds/vdpa_dev.h b/drivers/vdpa/pds/vdpa_dev.h
index 33284ebe538c..4e7a1b04a12a 100644
--- a/drivers/vdpa/pds/vdpa_dev.h
+++ b/drivers/vdpa/pds/vdpa_dev.h
@@ -43,6 +43,7 @@ struct pds_vdpa_device {
 	u8 vdpa_index;			/* rsvd for future subdevice use */
 	u8 num_vqs;			/* num vqs in use */
 	struct vdpa_callback config_cb;
+	struct notifier_block nb;
 };
 
 int pds_vdpa_get_mgmt_info(struct pds_vdpa_aux *vdpa_aux);
-- 
2.17.1