• Vitaly Kuznetsov's avatar
    ACPI / PCI: Bail early in acpi_pci_add_bus() if there is no ACPI handle · ff28e5cc
    Vitaly Kuznetsov authored
    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: 's avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Signed-off-by: 's avatarBjorn Helgaas <bhelgaas@google.com>
    Cc: Sinan Kaya <okaya@kernel.org>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    ff28e5cc