[PATCH v2 06/10] PCI/LUO: Save and restore driver name

Chris Li
2025-09-16T07:45:19Z

Save the PCI driver name into "struct pci_dev_ser" during the PCI
prepare callback.

After kexec, use driver_set_override() to ensure the device is
bound only to the saved driver.

Clear the override after the finish callback.

Signed-off-by: Chris Li <chrisl@kernel.org>
---
drivers/pci/liveupdate.c | 36 ++++++++++++++++++++++++++++++++++--
drivers/pci/pci.h | 2 ++
drivers/pci/probe.c | 2 ++
3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
index 41606df346f751c78f6c69caa275b4a76be72510..ae8f4dc5cf92577a4da83743c3b80bc72974a43e 100644
--- a/drivers/pci/liveupdate.c
+++ b/drivers/pci/liveupdate.c
@@ -21,6 +21,7 @@ static LIST_HEAD(probe_devices);
struct pci_dev_ser {
u32 path; /* domain + bus + slot + fn */
u32 flags;
+ char driver_name[63];
u64 driver_data; /* driver data */
};

@@ -87,6 +88,10 @@ static int build_liveupdate_devices(struct list_head *head)

static void dev_cleanup_liveupdate(struct device *dev)
{
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ if (liveupdate_state_updated())
+ WARN_ON(driver_set_override(dev, &pdev->driver_override, "", 0));
dev->lu.flags &= ~LU_DEPENDED;
dev->lu.dev_state = NULL;
list_del_init(&dev->lu.lu_next);
@@ -135,7 +140,13 @@ static int pci_get_device_path(struct pci_dev *pdev)
static int pci_save_device_state(struct device *dev, struct pci_dev_ser *s)
{
struct pci_dev *pdev = to_pci_dev(dev);
+ const char *name = dev->driver->name;

+ if (!name)
+ return -ENXIO;
+ if (strlen(name) > sizeof(s->driver_name) - 1)
+ return -ENOSPC;
+ strscpy(s->driver_name, name, sizeof(s->driver_name));
s->path = pci_get_device_path(pdev);
s->flags = dev->lu.flags;
return 0;
@@ -363,8 +374,8 @@ 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);
+ pci_info(dev, "liveupdate restore flags %x driver: %s data: [%llx]\n",
+ s->flags, s->driver_name, s->driver_data);
list_move_tail(&dev->dev.lu.lu_next, &probe_devices);
}

@@ -384,6 +395,27 @@ void pci_liveupdate_restore(struct pci_dev *dev)
return pci_dev_do_restore(dev, s);
}

+void pci_liveupdate_override_driver(struct pci_dev *dev)
+{
+ struct pci_dev_ser *s = dev->dev.lu.dev_state;
+ int ret;
+ int len;
+
+ if (!s)
+ return;
+
+ len = strlen(s->driver_name);
+ if (!len)
+ return;
+
+ ret = driver_set_override(&dev->dev,
+ &dev->driver_override,
+ s->driver_name, len);
+ if (ret)
+ panic("PCI Liveupdate override driver failed: %s", s->driver_name);
+}
+
+
static int __init pci_liveupdate_init(void)
{
int ret;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index c9a7383753949994e031dc362920286a475fe2ab..b79a18c5e948980fe2ef3f0a10e0d795b1eee6d7 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -1161,8 +1161,10 @@ static inline int pci_msix_write_tph_tag(struct pci_dev *pdev, unsigned int inde

#ifdef CONFIG_LIVEUPDATE
void pci_liveupdate_restore(struct pci_dev *dev);
+void pci_liveupdate_override_driver(struct pci_dev *dev);
#else
static inline void pci_liveupdate_restore(struct pci_dev *dev) {}
+static inline void pci_liveupdate_override_driver(struct pci_dev *dev) {}
#endif

#endif /* DRIVERS_PCI_H */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index a0605af1a699cd07b09897172803dcba1d2da9f9..e41a1bef2083aa9184fd1c894d5de964f19d5c01 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2714,6 +2714,8 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
/* Set up MSI IRQ domain */
pci_set_msi_domain(dev);

+ pci_liveupdate_override_driver(dev);
+
/* Notifier could use PCI capabilities */
ret = device_add(&dev->dev);
WARN_ON(ret < 0);

--
2.51.0.384.g4c02a37b29-goog