6.18-stable review patch. If anyone has any objections, please let me know.
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From: Ilpo Järvinen ilpo.jarvinen@linux.intel.com
[ Upstream commit 91c4c89db41499eea1b29c56655f79c3bae66e93 ]
pbus_reassign_bridge_resources() saves bridge windows into the saved list before attempting to adjust resource assignments to perform a BAR resize operation. If resource adjustments cannot be completed fully, rollback is attempted by restoring the resource from the saved list.
The rollback, however, does not check whether the resources it restores were assigned by the partial resize attempt. If restore changes addresses of the resource, it can result in corrupting the resource tree.
An example of a corrupted resource tree with overlapping addresses:
6200000000000-6203fbfffffff : pciex@620c3c0000000 6200000000000-6203fbff0ffff : PCI Bus 0030:01 6200020000000-62000207fffff : 0030:01:00.0 6200000000000-6203fbff0ffff : PCI Bus 0030:02
A resource that are assigned into the resource tree must remain unchanged. Thus, release such a resource before attempting to restore and claim it back.
For simplicity, always do the release and claim back for the resource even in the cases where it is restored to the same address range.
Note: this fix may "break" some cases where devices "worked" because the resource tree corruption allowed address space double counting to fit more resource than what can now be assigned without double counting. The upcoming changes to BAR resizing should address those scenarios (to the extent possible).
Fixes: 8bb705e3e79d ("PCI: Add pci_resize_resource() for resizing BARs") Reported-by: Simon Richter Simon.Richter@hogyros.de Link: https://lore.kernel.org/linux-pci/67840a16-99b4-4d8c-9b5c-4721ab0970a2@hogyr... Reported-by: Alex Bennée alex.bennee@linaro.org Link: https://lore.kernel.org/linux-pci/874irqop6b.fsf@draig.linaro.org/ Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Tested-by: Alex Bennée alex.bennee@linaro.org # AVA, AMD GPU Link: https://patch.msgid.link/20251113162628.5946-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/setup-bus.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 3645f392a9fd3..5ba878f15db35 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -2504,6 +2504,11 @@ int pbus_reassign_bridge_resources(struct pci_bus *bus, struct resource *res) bridge = dev_res->dev; i = pci_resource_num(bridge, res);
+ if (res->parent) { + release_child_resources(res); + pci_release_resource(bridge, i); + } + restore_dev_resource(dev_res);
pci_claim_resource(bridge, i);