4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> commit a0040c0145945d3bd203df8fa97f6dfa819f3f7d upstream. Hyper-V instances support PCI pass-through which is implemented through PV pci-hyperv driver. When a device is passed through, a new root PCI bus is created in the guest. The bus sits on top of VMBus and has no associated information in ACPI. acpi_pci_add_bus() in this case proceeds all the way to acpi_evaluate_dsm(), which reports ACPI: \: failed to evaluate _DSM (0x1001) While acpi_pci_slot_enumerate() and acpiphp_enumerate_slots() are protected against ACPI_HANDLE() being NULL and do nothing, acpi_evaluate_dsm() is not and gives us the error. It seems the correct fix is to not do anything in acpi_pci_add_bus() in such cases. Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Cc: Sinan Kaya <okaya@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/pci/pci-acpi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -543,7 +543,7 @@ void acpi_pci_add_bus(struct pci_bus *bu union acpi_object *obj; struct pci_host_bridge *bridge; - if (acpi_pci_disabled || !bus->bridge) + if (acpi_pci_disabled || !bus->bridge || !ACPI_HANDLE(bus->bridge)) return; acpi_pci_slot_enumerate(bus);
