[PATCH v2 04/10] PCI/LUO: Restore state at PCI enumeration

Chris Li
2025-09-16T07:45:18Z

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.

Restore the dev->lu.flags from the saved flags field.
Add such devices to the "probed_devices" list.

Signed-off-by: Chris Li <chrisl@kernel.org>
---
drivers/pci/liveupdate.c | 50 ++++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 6 +++++
drivers/pci/probe.c | 2 ++
include/linux/dev_liveupdate.h | 2 ++
4 files changed, 60 insertions(+)

diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
index 2b215c224fb78c908579b0d22be713e1dc7ca21f..305c5e85aba6bac9d02f97c83e7b3250298d2eff 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 */
@@ -87,6 +88,7 @@ static int build_liveupdate_devices(struct list_head *head)
static void dev_cleanup_liveupdate(struct device *dev)
{
dev->lu.flags &= ~LU_DEPENDED;
+ dev->lu.dev_state = NULL;
list_del_init(&dev->lu.lu_next);
}

@@ -306,6 +308,54 @@ 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;
+ dev->dev.lu.flags = s->flags;
+ pci_info(dev, "liveupdate restore flags %x data: [%llx]\n",
+ s->flags, 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 80a723c7701ac4ddc2ddd03d0ffc9cc5a62a6083..bb7ecf159dfa82e3779d938811541dddcf8f40af 100644
--- a/include/linux/dev_liveupdate.h
+++ b/include/linux/dev_liveupdate.h
@@ -27,6 +27,7 @@ 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.
* @flags: Indicate what liveupdate feature does the device
* participtate.
* @visited: Only used by the bus devices when travese the PCI buses
@@ -38,6 +39,7 @@ struct device;
*/
struct dev_liveupdate {
struct list_head lu_next;
+ void *dev_state;
enum liveupdate_flag flags;
bool visited:1;
};

--
2.51.0.384.g4c02a37b29-goog