Freeze a device's outgoing preservation status (preserved or not
preserved) during shutdown. This enables the PCI core and drivers to
safely make decisions based on the device's preservation status during
shutdown.

Note that pci_liveupdate_freeze() is triggered by the PCI core rather
than from drivers participating in Live Update so that all devices can
have their status frozen (i.e. prevent non-preserved devices from
getting preserved late).

Signed-off-by: David Matlack <dmatlack@google.com>
---
 drivers/pci/liveupdate.c       | 16 ++++++++++++++++
 drivers/pci/liveupdate.h       |  5 +++++
 drivers/pci/pci-driver.c       |  2 ++
 include/linux/pci_liveupdate.h |  3 +++
 4 files changed, 26 insertions(+)

diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
index 6ab03bd548b3..825166a57913 100644
--- a/drivers/pci/liveupdate.c
+++ b/drivers/pci/liveupdate.c
@@ -334,6 +334,11 @@ static int pci_liveupdate_unpreserve_device(struct pci_ser *ser, struct pci_dev
 
 	guard(write_lock)(&dev->liveupdate.lock);
 
+	if (dev->liveupdate.frozen) {
+		pci_WARN(dev, 1, "Cannot unpreserve device after it is frozen!\n");
+		return -EINVAL;
+	}
+
 	dev_ser = dev->liveupdate.outgoing;
 	if (!dev_ser) {
 		pci_warn(dev, "Cannot unpreserve device that is not preserved\n");
@@ -420,6 +425,11 @@ static int pci_liveupdate_preserve_device(struct pci_ser *ser, struct pci_dev *d
 {
 	guard(write_lock)(&dev->liveupdate.lock);
 
+	if (dev->liveupdate.frozen) {
+		pci_WARN(dev, 1, "Cannot preserve device after it is frozen!\n");
+		return -EINVAL;
+	}
+
 	if (dev->liveupdate.outgoing)
 		return pci_liveupdate_preserve_device_existing(dev);
 	else
@@ -625,6 +635,12 @@ void pci_liveupdate_cleanup_device(struct pci_dev *dev)
 		pci_liveupdate_flb_put_incoming();
 }
 
+void pci_liveupdate_freeze(struct pci_dev *dev)
+{
+	guard(write_lock)(&dev->liveupdate.lock);
+	dev->liveupdate.frozen = 1;
+}
+
 static int __pci_liveupdate_finish_device(struct pci_dev *dev)
 {
 	guard(write_lock)(&dev->liveupdate.lock);
diff --git a/drivers/pci/liveupdate.h b/drivers/pci/liveupdate.h
index fd7693c7ddd2..30deaa673efe 100644
--- a/drivers/pci/liveupdate.h
+++ b/drivers/pci/liveupdate.h
@@ -13,6 +13,7 @@
 #ifdef CONFIG_PCI_LIVEUPDATE
 void pci_liveupdate_setup_device(struct pci_dev *dev);
 void pci_liveupdate_cleanup_device(struct pci_dev *dev);
+void pci_liveupdate_freeze(struct pci_dev *dev);
 bool pci_liveupdate_inherit_buses(void);
 void pci_liveupdate_init_acs(struct pci_dev *dev);
 bool pci_liveupdate_inherit_acs(struct pci_dev *dev);
@@ -26,6 +27,10 @@ static inline void pci_liveupdate_cleanup_device(struct pci_dev *dev)
 {
 }
 
+static inline void pci_liveupdate_freeze(struct pci_dev *dev);
+{
+}
+
 static inline bool pci_liveupdate_inherit_buses(void)
 {
 	return false;
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index d10ece0889f0..f7a5e65a7c75 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -21,6 +21,7 @@
 #include <linux/acpi.h>
 #include <linux/dma-map-ops.h>
 #include <linux/iommu.h>
+#include "liveupdate.h"
 #include "pci.h"
 #include "pcie/portdrv.h"
 
@@ -536,6 +537,7 @@ static void pci_device_shutdown(struct device *dev)
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	struct pci_driver *drv = pci_dev->driver;
 
+	pci_liveupdate_freeze(pci_dev);
 	pm_runtime_resume(dev);
 
 	if (drv && drv->shutdown)
diff --git a/include/linux/pci_liveupdate.h b/include/linux/pci_liveupdate.h
index 34f9900c7d29..7e4ac7a0f4fc 100644
--- a/include/linux/pci_liveupdate.h
+++ b/include/linux/pci_liveupdate.h
@@ -22,6 +22,8 @@
  * @was_preserved: True if this struct pci_dev was preserved by the previous
  *                 kernel. Unlike @incoming, this field is not cleared after
  *                 the device is finished participating in Live Update.
+ * @frozen: True if the outgoing preservation status of this device is frozen
+ *          and thus cannot be changed.
  */
 struct pci_liveupdate {
 	rwlock_t lock;
@@ -29,6 +31,7 @@ struct pci_liveupdate {
 	struct pci_dev_ser *incoming;
 	u16 acs_ctrl;
 	unsigned int was_preserved:1;
+	unsigned int frozen:1;
 };
 
 struct pci_dev;
-- 
2.54.0.563.g4f69b47b94-goog