ice: use DSN instead of PCI BDF for ice_adapter index

Use Device Serial Number instead of PCI bus/device/function for
the index of struct ice_adapter.

Functions on the same physical device should point to the very same
ice_adapter instance, but with two PFs, when at least one of them is
PCI-e passed-through to a VM, it is no longer the case - PFs will get
seemingly random PCI BDF values, and thus indices, what finally leds to
each of them being on their own instance of ice_adapter. That causes them
to don't attempt any synchronization of the PTP HW clock usage, or any
other future resources.

DSN works nicely in place of the index, as it is "immutable" in terms of
virtualization.

Fixes: 0e2bddf ("ice: add ice_adapter for shared data across PFs on the same NIC")
Suggested-by: Jacob Keller <[email protected]>
Suggested-by: Jakub Kicinski <[email protected]>
Suggested-by: Jiri Pirko <[email protected]>
Reviewed-by: Aleksandr Loktionov <[email protected]>
Signed-off-by: Przemek Kitszel <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Tested-by: Rinitha S <[email protected]> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: pkitszel

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>
@@ -14,39 +13,24 @@
 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)
+static struct ice_adapter *ice_adapter_new(u64 dsn)
 {
 	struct ice_adapter *adapter;
 
 	adapter = kzalloc(sizeof(*adapter), GFP_KERNEL);
 	if (!adapter)
 		return NULL;
 
+	adapter->device_serial_number = dsn;
 	spin_lock_init(&adapter->ptp_gltsyn_time_lock);
 	refcount_set(&adapter->refcount, 1);
 
@@ -77,23 +61,26 @@ 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();
+		adapter = ice_adapter_new(dsn);
 		if (!adapter)
 			return ERR_PTR(-ENOMEM);
 		xa_store(&ice_adapters, index, adapter, GFP_KERNEL);
@@ -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))

drivers/net/ethernet/intel/ice/ice_adapter.h

@@ -32,6 +32,7 @@ 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;
@@ -40,9 +41,10 @@ struct ice_adapter {
 
 	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 */