[PATCH RFC 05/25] PCI/LUO: Restore state at PCI enumeration

[Chris Li <chrisl@xxxxxxxxxx>]

Add a PCI device saved state member to indicate the device is requested
vs depended.

Restore the PCI subsystem saved state folio during PCI enumeration.

When a new PCI device is created, restore the per device state pointer
into the dev->lu.dev_state if the device is found in the saved
devices array, by matching the device path.

Also restore the dev->lu.requested or dev->lu.depended base on the saved
"requested" field. Add such devices to the "probed_devices" list.

Signed-off-by: Chris Li <chrisl@xxxxxxxxxx>
---
 drivers/pci/liveupdate.c       | 54 ++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h              |  6 +++++
 drivers/pci/probe.c            |  2 ++
 include/linux/dev_liveupdate.h |  2 ++
 4 files changed, 64 insertions(+)

diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
index bbff9b314f99185dfe8941b711cdf0db16b1ed8a..4d13071f5edd6520adb64003262f08d1f79e26c4 100644
--- a/drivers/pci/liveupdate.c
+++ b/drivers/pci/liveupdate.c
@@ -16,6 +16,7 @@
 #define PCI_SUBSYSTEM_NAME "pci"
 
 static LIST_HEAD(preserved_devices);
+static LIST_HEAD(probe_devices);
 
 struct pci_dev_ser {
 	u32	path;		/* domain + bus + slot + fn */
@@ -91,6 +92,7 @@ static int build_liveupdate_devices(struct list_head *head)
 static void dev_cleanup_liveupdate(struct device *dev)
 {
 	dev->lu.depended = 0;
+	dev->lu.dev_state = NULL;
 	list_del_init(&dev->lu.lu_next);
 }
 
@@ -310,6 +312,58 @@ struct liveupdate_subsystem pci_liveupdate_ops = {
 	.name = PCI_SUBSYSTEM_NAME,
 };
 
+static struct pci_ser *pci_state_get(void)
+{
+	static struct pci_ser *pci_state;
+	struct folio *folio;
+	phys_addr_t data = 0;
+	int ret;
+
+	if (pci_state)
+		return pci_state;
+
+	ret = liveupdate_get_subsystem_data(&pci_liveupdate_ops, &data);
+	if (ret || !data)
+		panic("PCI liveupdate: get subsystem data: [%llx] ret: %d", data, ret);
+
+	folio = kho_restore_folio(data);
+	if (!folio)
+		panic("PCI liveupdate: restore folio from %llx failed", data);
+
+	/* Cache the value for future callers. */
+	pci_state = folio_address(folio);
+	return pci_state;
+}
+
+static void pci_dev_do_restore(struct pci_dev *dev, struct pci_dev_ser *s)
+{
+	dev->dev.lu.dev_state = s;
+	if (s->requested)
+		dev->dev.lu.requested = 1;
+	else
+		dev->dev.lu.depended = 1;
+	pci_info(dev, "liveupdate restore [%s] data: [%llx]\n",
+		 s->requested ? "requested" : "depended",
+		 s->driver_data);
+	list_move_tail(&dev->dev.lu.lu_next, &probe_devices);
+}
+
+void pci_liveupdate_restore(struct pci_dev *dev)
+{
+	int path;
+	struct pci_dev_ser *s, *end;
+
+	if (!liveupdate_state_updated())
+		return;
+
+	path = pci_get_device_path(dev);
+	s = pci_state_get()->devs;
+	end = s + pci_state_get()->count;
+	for (; s < end; s++)
+		if (s->path == path)
+			return pci_dev_do_restore(dev, s);
+}
+
 static int __init pci_liveupdate_init(void)
 {
 	int ret;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 12215ee72afb682b669c0e3a582b5379828e70c4..c9a7383753949994e031dc362920286a475fe2ab 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -1159,4 +1159,10 @@ static inline int pci_msix_write_tph_tag(struct pci_dev *pdev, unsigned int inde
 	(PCI_CONF1_ADDRESS(bus, dev, func, reg) | \
 	 PCI_CONF1_EXT_REG(reg))
 
+#ifdef CONFIG_LIVEUPDATE
+void pci_liveupdate_restore(struct pci_dev *dev);
+#else
+static inline void pci_liveupdate_restore(struct pci_dev *dev) {}
+#endif
+
 #endif /* DRIVERS_PCI_H */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index dddd7ebc03d1a6e6ee456e0bf02ab9833a819509..a0605af1a699cd07b09897172803dcba1d2da9f9 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2017,6 +2017,8 @@ int pci_setup_device(struct pci_dev *dev)
 	if (pci_early_dump)
 		early_dump_pci_device(dev);
 
+	pci_liveupdate_restore(dev);
+
 	/* Need to have dev->class ready */
 	dev->cfg_size = pci_cfg_space_size(dev);
 
diff --git a/include/linux/dev_liveupdate.h b/include/linux/dev_liveupdate.h
index fa664976f9f5e90b8a5a17cfbed8bd2fdc87b7a1..dc65e2b2d92c02bf15440b6745c62cd748721eef 100644
--- a/include/linux/dev_liveupdate.h
+++ b/include/linux/dev_liveupdate.h
@@ -19,6 +19,7 @@ struct device;
  * @lu_next:	List head for linking the device into live update
  *		related lists (e.g., a list of devices participating
  *		in a live update sequence).
+ * @dev_state:	Set to the device state at restore.
  * @requested:	Set if a live update has been requested for this
  *		device (i.e. device will participate in live update).
  * @depended:	Set if the device participtate the live update due to
@@ -32,6 +33,7 @@ struct device;
  */
 struct dev_liveupdate {
 	struct list_head lu_next;
+	void *dev_state;
 	bool requested:1;
 	bool depended:1;
 	bool visited:1;

-- 
2.50.1.487.gc89ff58d15-goog