• Bjorn Helgaas's avatar
    PCI: Don't check resource_size() in pci_bus_alloc_resource() · ac93ac74
    Bjorn Helgaas authored
    Paul reported that after f75b99d5 ("PCI: Enforce bus address limits in
    resource allocation") on a 32-bit kernel (CONFIG_PHYS_ADDR_T_64BIT not
    set), intel-gtt complained "can't ioremap flush page - no chipset
    flushing".  In addition, other PCI resource allocations, e.g., for bridge
    windows, failed.
    
    This happens because we incorrectly skip bus resources of
    [mem 0x00000000-0xffffffff] because we think they are of size zero.
    When resource_size_t is 32 bits wide, resource_size() on
    [mem 0x00000000-0xffffffff] returns 0 because (r->end - r->start + 1)
    overflows.
    
    Therefore, we can't use "resource_size() == 0" to decide that allocation
    from this resource will fail.  allocate_resource() should fail anyway if it
    can't satisfy the address constraints, so we should just depend on that.
    
    A [mem 0x00000000-0xffffffff] bus resource is obviously not really valid,
    but we do fall back to it as a default when we don't have information about
    host bridge apertures.
    
    Link: https://bugzilla.kernel.org/show_bug.cgi?id=71611
    Fixes: f75b99d5 PCI: Enforce bus address limits in resource allocation
    Reported-and-tested-by: default avatarPaul Bolle <pebolle@tiscali.nl>
    Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    ac93ac74
bus.c 8.68 KB