[PATCH] PCI: mark Thunderbolt-attached devices as removable

[Geramy Loveless <gloveless@jqluv.com>]

pci_set_removable() only marks devices as removable if their upstream
bridge has the ACPI ExternalFacingPort property set.  Some firmware
(e.g. MSI MS-S1 MAX with AMD Strix Halo) does not set this property on
Thunderbolt root ports, so devices behind them are never marked
removable.  This causes all drivers that use dev_is_removable() to miss
eGPU-specific code paths.

Fall back to pci_is_thunderbolt_attached() when the parent is not
already marked removable.  set_pcie_thunderbolt() runs before
pci_set_removable() during device add, so the is_thunderbolt flag is
already available.

This fixes the problem at the PCI core level so all drivers benefit
from correct removable detection, not just individual drivers that add
their own Thunderbolt checks.

Signed-off-by: Geramy Loveless <gloveless@jqluv.com>
---
 drivers/pci/probe.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index bccc7a4bdd7..2387edc5b89 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1761,17 +1761,23 @@ static void pci_set_removable(struct pci_dev *dev)
 	if (!parent)
 		return;
 	/*
-	 * We (only) consider everything tunneled below an external_facing
-	 * device to be removable by the user. We're mainly concerned with
-	 * consumer platforms with user accessible thunderbolt ports that are
-	 * vulnerable to DMA attacks, and we expect those ports to be marked by
-	 * the firmware as external_facing. Devices in traditional hotplug
-	 * slots can technically be removed, but the expectation is that unless
-	 * the port is marked with external_facing, such devices are less
+	 * We consider everything tunneled below an external_facing device to
+	 * be removable by the user. We're mainly concerned with consumer
+	 * platforms with user accessible thunderbolt ports that are vulnerable
+	 * to DMA attacks, and we expect those ports to be marked by the
+	 * firmware as external_facing. Devices in traditional hotplug slots
+	 * can technically be removed, but the expectation is that unless the
+	 * port is marked with external_facing, such devices are less
 	 * accessible to user / may not be removed by end user, and thus not
 	 * exposed as "removable" to userspace.
+	 *
+	 * Some firmware does not set the ExternalFacingPort property on
+	 * Thunderbolt root ports.  In that case, fall back to checking
+	 * whether the device sits below a Thunderbolt controller, which
+	 * is itself inherently user-removable.
 	 */
-	if (dev_is_removable(&parent->dev)) {
+	if (dev_is_removable(&parent->dev) ||
+	    pci_is_thunderbolt_attached(dev)) {
 		dev_set_removable(&dev->dev, DEVICE_REMOVABLE);
 		return;
 	}
-- 
2.43.0