[patch net-next] net: mana: Handle hardware reset events when probing the device

[longli@linux.microsoft.com]

From: Long Li <longli@microsoft.com>

When MANA is being probed, it's possible that hardware is in recovery
mode and the device may get GDMA_EQE_HWC_RESET_REQUEST over HWC in the
middle of the probe. Detect such condition and go through the recovery
service procedure.

Fixes: fbe346ce9d62 ("net: mana: Handle Reset Request from MANA NIC")
Signed-off-by: Long Li <longli@microsoft.com>
---
 .../net/ethernet/microsoft/mana/gdma_main.c   | 131 +++++++++++++++---
 include/net/mana/gdma.h                       |   9 +-
 2 files changed, 122 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index effe0a2f207a..1d9c2beb22b2 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -15,6 +15,12 @@
 
 struct dentry *mana_debugfs_root;
 
+static struct mana_serv_delayed_work {
+	struct delayed_work work;
+	struct pci_dev *pdev;
+	enum gdma_eqe_type type;
+} mns_delayed_wk;
+
 static u32 mana_gd_r32(struct gdma_context *g, u64 offset)
 {
 	return readl(g->bar0_va + offset);
@@ -387,6 +393,25 @@ EXPORT_SYMBOL_NS(mana_gd_ring_cq, "NET_MANA");
 
 #define MANA_SERVICE_PERIOD 10
 
+static void mana_serv_rescan(struct pci_dev *pdev)
+{
+	struct pci_bus *parent;
+
+	pci_lock_rescan_remove();
+
+	parent = pdev->bus;
+	if (!parent) {
+		dev_err(&pdev->dev, "MANA service: no parent bus\n");
+		goto out;
+	}
+
+	pci_stop_and_remove_bus_device(pdev);
+	pci_rescan_bus(parent);
+
+out:
+	pci_unlock_rescan_remove();
+}
+
 static void mana_serv_fpga(struct pci_dev *pdev)
 {
 	struct pci_bus *bus, *parent;
@@ -419,9 +444,12 @@ static void mana_serv_reset(struct pci_dev *pdev)
 {
 	struct gdma_context *gc = pci_get_drvdata(pdev);
 	struct hw_channel_context *hwc;
+	int ret;
 
 	if (!gc) {
-		dev_err(&pdev->dev, "MANA service: no GC\n");
+		/* Perform PCI rescan on device if GC is not set up */
+		dev_err(&pdev->dev, "MANA service: GC not setup, rescanning\n");
+		mana_serv_rescan(pdev);
 		return;
 	}
 
@@ -440,9 +468,18 @@ static void mana_serv_reset(struct pci_dev *pdev)
 
 	msleep(MANA_SERVICE_PERIOD * 1000);
 
-	mana_gd_resume(pdev);
+	ret = mana_gd_resume(pdev);
+	if (ret == -ETIMEDOUT || ret == -EPROTO) {
+		/* Perform PCI rescan on device if we failed on HWC */
+		dev_err(&pdev->dev, "MANA service: resume failed, rescanning\n");
+		mana_serv_rescan(pdev);
+		goto out;
+	}
 
-	dev_info(&pdev->dev, "MANA reset cycle completed\n");
+	if (ret)
+		dev_info(&pdev->dev, "MANA reset cycle failed err %d\n", ret);
+	else
+		dev_info(&pdev->dev, "MANA reset cycle completed\n");
 
 out:
 	gc->in_service = false;
@@ -454,18 +491,9 @@ struct mana_serv_work {
 	enum gdma_eqe_type type;
 };
 
-static void mana_serv_func(struct work_struct *w)
+static void mana_do_service(enum gdma_eqe_type type, struct pci_dev *pdev)
 {
-	struct mana_serv_work *mns_wk;
-	struct pci_dev *pdev;
-
-	mns_wk = container_of(w, struct mana_serv_work, serv_work);
-	pdev = mns_wk->pdev;
-
-	if (!pdev)
-		goto out;
-
-	switch (mns_wk->type) {
+	switch (type) {
 	case GDMA_EQE_HWC_FPGA_RECONFIG:
 		mana_serv_fpga(pdev);
 		break;
@@ -475,12 +503,36 @@ static void mana_serv_func(struct work_struct *w)
 		break;
 
 	default:
-		dev_err(&pdev->dev, "MANA service: unknown type %d\n",
-			mns_wk->type);
+		dev_err(&pdev->dev, "MANA service: unknown type %d\n", type);
 		break;
 	}
+}
+
+static void mana_serv_delayed_func(struct work_struct *w)
+{
+	struct mana_serv_delayed_work *dwork;
+	struct pci_dev *pdev;
+
+	dwork = container_of(w, struct mana_serv_delayed_work, work.work);
+	pdev = dwork->pdev;
+
+	if (pdev)
+		mana_do_service(dwork->type, pdev);
+
+	pci_dev_put(pdev);
+}
+
+static void mana_serv_func(struct work_struct *w)
+{
+	struct mana_serv_work *mns_wk;
+	struct pci_dev *pdev;
+
+	mns_wk = container_of(w, struct mana_serv_work, serv_work);
+	pdev = mns_wk->pdev;
+
+	if (pdev)
+		mana_do_service(mns_wk->type, pdev);
 
-out:
 	pci_dev_put(pdev);
 	kfree(mns_wk);
 	module_put(THIS_MODULE);
@@ -541,6 +593,17 @@ static void mana_gd_process_eqe(struct gdma_queue *eq)
 	case GDMA_EQE_HWC_RESET_REQUEST:
 		dev_info(gc->dev, "Recv MANA service type:%d\n", type);
 
+		if (atomic_inc_return(&gc->in_probe) == 1) {
+			/*
+			 * Device is in probe and we received an hardware reset
+			 * event, probe() will detect that "in_probe" has
+			 * changed and perform service procedure.
+			 */
+			dev_info(gc->dev,
+				 "Service is to be processed in probe\n");
+			break;
+		}
+
 		if (gc->in_service) {
 			dev_info(gc->dev, "Already in service\n");
 			break;
@@ -1930,6 +1993,8 @@ static int mana_gd_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		gc->mana_pci_debugfs = debugfs_create_dir(pci_slot_name(pdev->slot),
 							  mana_debugfs_root);
 
+	atomic_set(&gc->in_probe, 0);
+
 	err = mana_gd_setup(pdev);
 	if (err)
 		goto unmap_bar;
@@ -1942,8 +2007,19 @@ static int mana_gd_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (err)
 		goto cleanup_mana;
 
+	/*
+	 * If a hardware reset event has occurred over HWC during probe,
+	 * rollback and perform hardware reset procedure.
+	 */
+	if (atomic_inc_return(&gc->in_probe) > 1) {
+		err = -EPROTO;
+		goto cleanup_mana_rdma;
+	}
+
 	return 0;
 
+cleanup_mana_rdma:
+	mana_rdma_remove(&gc->mana_ib);
 cleanup_mana:
 	mana_remove(&gc->mana, false);
 cleanup_gd:
@@ -1967,6 +2043,25 @@ static int mana_gd_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 disable_dev:
 	pci_disable_device(pdev);
 	dev_err(&pdev->dev, "gdma probe failed: err = %d\n", err);
+
+	/*
+	 * Hardware could be in recovery mode and the HWC returns TIMEDOUT or
+	 * EPROTO from mana_gd_setup(), mana_probe() or mana_rdma_probe(), or
+	 * we received a hardware reset event over HWC interrupt. In this case,
+	 * perform the device recovery procedure after MANA_SERVICE_PERIOD
+	 * seconds.
+	 */
+	if (err == -ETIMEDOUT || err == -EPROTO) {
+		dev_info(&pdev->dev, "Start MANA recovery mode\n");
+
+		mns_delayed_wk.pdev = pci_dev_get(pdev);
+		mns_delayed_wk.type = GDMA_EQE_HWC_RESET_REQUEST;
+
+		INIT_DELAYED_WORK(&mns_delayed_wk.work, mana_serv_delayed_func);
+		schedule_delayed_work(&mns_delayed_wk.work,
+				      secs_to_jiffies(MANA_SERVICE_PERIOD));
+	}
+
 	return err;
 }
 
@@ -2084,6 +2179,8 @@ static int __init mana_driver_init(void)
 
 static void __exit mana_driver_exit(void)
 {
+	cancel_delayed_work_sync(&mns_delayed_wk.work);
+
 	pci_unregister_driver(&mana_driver);
 
 	debugfs_remove(mana_debugfs_root);
diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h
index 637f42485dba..1bb4c6ada2b6 100644
--- a/include/net/mana/gdma.h
+++ b/include/net/mana/gdma.h
@@ -430,6 +430,9 @@ struct gdma_context {
 	u64 pf_cap_flags1;
 
 	struct workqueue_struct *service_wq;
+
+	/* Count how many times we have finished probe or HWC events */
+	atomic_t		in_probe;
 };
 
 static inline bool mana_gd_is_mana(struct gdma_dev *gd)
@@ -592,6 +595,9 @@ enum {
 #define GDMA_DRV_CAP_FLAG_1_HANDLE_RECONFIG_EQE BIT(17)
 #define GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE BIT(6)
 
+/* Driver can handle hardware reset events during probe */
+#define GDMA_DRV_CAP_FLAG_1_RECOVER_PROBE BIT(22)
+
 #define GDMA_DRV_CAP_FLAGS1 \
 	(GDMA_DRV_CAP_FLAG_1_EQ_SHARING_MULTI_VPORT | \
 	 GDMA_DRV_CAP_FLAG_1_NAPI_WKDONE_FIX | \
@@ -601,7 +607,8 @@ enum {
 	 GDMA_DRV_CAP_FLAG_1_DYNAMIC_IRQ_ALLOC_SUPPORT | \
 	 GDMA_DRV_CAP_FLAG_1_SELF_RESET_ON_EQE | \
 	 GDMA_DRV_CAP_FLAG_1_HANDLE_RECONFIG_EQE | \
-	 GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE)
+	 GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE | \
+	 GDMA_DRV_CAP_FLAG_1_RECOVER_PROBE)
 
 #define GDMA_DRV_CAP_FLAGS2 0
 
-- 
2.43.0