[PATCH iwl-net v2] ice: use DSN instead of PCI BDF for ice_adapter index

[Przemek Kitszel <przemyslaw.kitszel@intel.com>]

Use Device Serial Number instead of PCI bus/device/function for
index of struct ice_adapter.
Functions on the same physical device should point to the very same
ice_adapter instance.

This is not only simplification, but also fixes things up when PF
is passed to VM (and thus has a random BDF).

Suggested-by: Jacob Keller <jacob.e.keller@intel.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Suggested-by: Jiri Pirko <jiri@resnulli.us>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
---
CC: Karol Kolacinski <karol.kolacinski@intel.com>
CC: Grzegorz Nitka <grzegorz.nitka@intel.com>
CC: Michal Schmidt <mschmidt@redhat.com>
CC: Sergey Temerkhanov <sergey.temerkhanov@intel.com>

v2:
 - target to -net (Jiri)
 - mix both halves of u64 DSN on 32bit systems (Jiri)
 - (no changes in terms of fallbacks for pre-prod HW)
 - warn when there is DSN collision after reducing to 32bit

v1:
https://lore.kernel.org/netdev/20250306211159.3697-2-przemyslaw.kitszel@intel.com
---
 drivers/net/ethernet/intel/ice/ice_adapter.h |  6 ++-
 drivers/net/ethernet/intel/ice/ice_adapter.c | 43 ++++++++------------
 2 files changed, 20 insertions(+), 29 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.h b/drivers/net/ethernet/intel/ice/ice_adapter.h
index e233225848b3..ac15c0d2bc1a 100644
--- a/drivers/net/ethernet/intel/ice/ice_adapter.h
+++ b/drivers/net/ethernet/intel/ice/ice_adapter.h
@@ -32,17 +32,19 @@ struct ice_port_list {
  * @refcount: Reference count. struct ice_pf objects hold the references.
  * @ctrl_pf: Control PF of the adapter
  * @ports: Ports list
+ * @device_serial_number: DSN cached for collision detection on 32bit systems
  */
 struct ice_adapter {
 	refcount_t refcount;
 	/* For access to the GLTSYN_TIME register */
 	spinlock_t ptp_gltsyn_time_lock;
 
 	struct ice_pf *ctrl_pf;
 	struct ice_port_list ports;
+	u64 device_serial_number;
 };
 
-struct ice_adapter *ice_adapter_get(const struct pci_dev *pdev);
-void ice_adapter_put(const struct pci_dev *pdev);
+struct ice_adapter *ice_adapter_get(struct pci_dev *pdev);
+void ice_adapter_put(struct pci_dev *pdev);
 
 #endif /* _ICE_ADAPTER_H */
diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.c b/drivers/net/ethernet/intel/ice/ice_adapter.c
index 01a08cfd0090..3df3fa6d5129 100644
--- a/drivers/net/ethernet/intel/ice/ice_adapter.c
+++ b/drivers/net/ethernet/intel/ice/ice_adapter.c
@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 // SPDX-FileCopyrightText: Copyright Red Hat
 
-#include <linux/bitfield.h>
 #include <linux/cleanup.h>
 #include <linux/mutex.h>
 #include <linux/pci.h>
@@ -14,29 +13,13 @@
 static DEFINE_XARRAY(ice_adapters);
 static DEFINE_MUTEX(ice_adapters_mutex);
 
-/* PCI bus number is 8 bits. Slot is 5 bits. Domain can have the rest. */
-#define INDEX_FIELD_DOMAIN GENMASK(BITS_PER_LONG - 1, 13)
-#define INDEX_FIELD_DEV    GENMASK(31, 16)
-#define INDEX_FIELD_BUS    GENMASK(12, 5)
-#define INDEX_FIELD_SLOT   GENMASK(4, 0)
-
-static unsigned long ice_adapter_index(const struct pci_dev *pdev)
+static unsigned long ice_adapter_index(u64 dsn)
 {
-	unsigned int domain = pci_domain_nr(pdev->bus);
-
-	WARN_ON(domain > FIELD_MAX(INDEX_FIELD_DOMAIN));
-
-	switch (pdev->device) {
-	case ICE_DEV_ID_E825C_BACKPLANE:
-	case ICE_DEV_ID_E825C_QSFP:
-	case ICE_DEV_ID_E825C_SFP:
-	case ICE_DEV_ID_E825C_SGMII:
-		return FIELD_PREP(INDEX_FIELD_DEV, pdev->device);
-	default:
-		return FIELD_PREP(INDEX_FIELD_DOMAIN, domain) |
-		       FIELD_PREP(INDEX_FIELD_BUS,    pdev->bus->number) |
-		       FIELD_PREP(INDEX_FIELD_SLOT,   PCI_SLOT(pdev->devfn));
-	}
+#if BITS_PER_LONG == 64
+	return dsn;
+#else
+	return (u32)dsn ^ u32(dsn >> 32);
+#endif
 }
 
 static struct ice_adapter *ice_adapter_new(void)
@@ -77,25 +60,29 @@ static void ice_adapter_free(struct ice_adapter *adapter)
  * Return:  Pointer to ice_adapter on success.
  *          ERR_PTR() on error. -ENOMEM is the only possible error.
  */
-struct ice_adapter *ice_adapter_get(const struct pci_dev *pdev)
+struct ice_adapter *ice_adapter_get(struct pci_dev *pdev)
 {
-	unsigned long index = ice_adapter_index(pdev);
+	u64 dsn = pci_get_dsn(pdev);
 	struct ice_adapter *adapter;
+	unsigned long index;
 	int err;
 
+	index = ice_adapter_index(dsn);
 	scoped_guard(mutex, &ice_adapters_mutex) {
 		err = xa_insert(&ice_adapters, index, NULL, GFP_KERNEL);
 		if (err == -EBUSY) {
 			adapter = xa_load(&ice_adapters, index);
 			refcount_inc(&adapter->refcount);
+			WARN_ON_ONCE(adapter->device_serial_number != dsn);
 			return adapter;
 		}
 		if (err)
 			return ERR_PTR(err);
 
 		adapter = ice_adapter_new();
 		if (!adapter)
 			return ERR_PTR(-ENOMEM);
+		adapter->device_serial_number = dsn;
 		xa_store(&ice_adapters, index, adapter, GFP_KERNEL);
 	}
 	return adapter;
@@ -110,11 +97,13 @@ struct ice_adapter *ice_adapter_get(const struct pci_dev *pdev)
  *
  * Context: Process, may sleep.
  */
-void ice_adapter_put(const struct pci_dev *pdev)
+void ice_adapter_put(struct pci_dev *pdev)
 {
-	unsigned long index = ice_adapter_index(pdev);
+	u64 dsn = pci_get_dsn(pdev);
 	struct ice_adapter *adapter;
+	unsigned long index;
 
+	index = ice_adapter_index(dsn);
 	scoped_guard(mutex, &ice_adapters_mutex) {
 		adapter = xa_load(&ice_adapters, index);
 		if (WARN_ON(!adapter))
-- 
2.39.3