[PATCH 08/10] PCI: liveupdate: Prevent releasing resource windows of incoming bridges

[David Matlack <dmatlack@google.com>]

Prevent the windows of bridges preserved across Live Update from being
released during the recursive "realloc" failure paths by adding a check
for pci_liveupdate_is_incoming() to pci_bridge_release_resources(), and
log that the window was not released, similar to the message that
pci_release_resource() logs when it releases a window.

This prevents the PCI core from forcibly releasing a preserved bridge
window to satisfy the resource needs of a failing child device.
Instead, the child's resources simply fail to be allocated. This should
never happen in practice though, since the previous kernel should have
established a sane resource allocation before kexec.

Assisted-by: LLM
Signed-off-by: David Matlack <dmatlack@google.com>
---
 drivers/pci/setup-bus.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index b82440394ee2..7283c4be803e 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1700,6 +1700,12 @@ static void pci_bridge_release_resources(struct pci_bus *bus,
 
 	idx = pci_resource_num(dev, b_win);
 
+	if (pci_liveupdate_is_incoming(dev)) {
+		pci_info(dev, "%s %pR: not releasing window of bridge preserved across Live Update\n",
+			 pci_resource_name(dev, idx), b_win);
+		return;
+	}
+
 	/* If there are children, release them all */
 	release_child_resources(b_win);
 
-- 
2.56.0.212.g129ede20d9-goog