[PATCH v9 11/13] PCI: liveupdate: Freeze preservation status during shutdown

[David Matlack <dmatlack@google.com>]

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).

Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
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 3c9a10a892fc..496ba74c26ce 100644
--- a/drivers/pci/liveupdate.c
+++ b/drivers/pci/liveupdate.c
@@ -481,6 +481,11 @@ static int pci_liveupdate_unpreserve_device(struct pci_flb_outgoing *outgoing,
 {
 	struct pci_dev_ser *dev_ser = dev->liveupdate.outgoing;
 
+	if (dev->liveupdate.frozen) {
+		pci_warn(dev, "Cannot unpreserve device after it is frozen!\n");
+		return -EINVAL;
+	}
+
 	if (!dev_ser) {
 		pci_warn(dev, "Cannot unpreserve device that is not preserved\n");
 		return -EINVAL;
@@ -547,6 +552,11 @@ static int pci_liveupdate_preserve_device(struct pci_flb_outgoing *outgoing,
 		return -EINVAL;
 	}
 
+	if (dev->liveupdate.frozen) {
+		pci_warn(dev, "Cannot preserve device after it is frozen!\n");
+		return -EINVAL;
+	}
+
 	if (!dev->liveupdate.outgoing) {
 		struct pci_dev_ser *dev_ser;
 
@@ -797,6 +807,12 @@ void pci_liveupdate_cleanup_device(struct pci_dev *dev)
 		pci_WARN(dev, 1, "Destroying incoming-preserved device!\n");
 }
 
+void pci_liveupdate_freeze(struct pci_dev *dev)
+{
+	guard(rwsem_write)(&pci_liveupdate.rwsem);
+	dev->liveupdate.frozen = true;
+}
+
 static int pci_liveupdate_finish_device(struct pci_ser *ser, struct pci_dev *dev)
 {
 	if (!dev->liveupdate.incoming) {
diff --git a/drivers/pci/liveupdate.h b/drivers/pci/liveupdate.h
index 90b2754ecc0c..5aac19f7bee6 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_preserve_bus_numbers(void);
 bool pci_liveupdate_refuse_bus_numbers(struct pci_bus *bus, struct pci_dev *dev);
 int pci_liveupdate_adopt_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_preserve_bus_numbers(void)
 {
 	return false;
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index e16aa59dd7ac..dff60a03204f 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"
 
@@ -559,6 +560,7 @@ 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 d45a5b524909..bb79348769b7 100644
--- a/include/linux/pci_liveupdate.h
+++ b/include/linux/pci_liveupdate.h
@@ -21,11 +21,14 @@
  *                set up, i.e. it was matched to state preserved by the previous
  *                kernel. Unlike @incoming, this is never cleared, so it stays
  *                true after the device finishes participating in Live Update.
+ * @frozen: True if the outgoing preservation status of this device is frozen
+ *          and thus cannot be changed.
  */
 struct pci_liveupdate {
 	struct pci_dev_ser *outgoing;
 	struct pci_dev_ser *incoming;
 	bool was_incoming;
+	bool frozen;
 };
 
 struct pci_dev;
-- 
2.55.0.1082.g2b9226bbc0-goog