• Lorenzo Pieralisi's avatar
    PCI: versatile: Fix pci_remap_iospace() failure path · 53f4f7ee
    Lorenzo Pieralisi authored
    On ARM/ARM64 architectures, PCI IO ports are emulated through memory mapped
    IO, by reserving a chunk of virtual address space starting at PCI_IOBASE
    and by mapping the PCI host bridges memory address space driving PCI IO
    cycles to it.
    
    PCI host bridge drivers that enable downstream PCI IO cycles map the host
    bridge memory address responding to PCI IO cycles to the fixed virtual
    address space through the pci_remap_iospace() API.
    
    This means that if the pci_remap_iospace() function fails, the
    corresponding host bridge PCI IO resource must be considered invalid, in
    that there is no way for the kernel to actually drive PCI IO transactions
    if the memory addresses responding to PCI IO cycles cannot be mapped into
    the CPU virtual address space.
    
    The PCI versatile host bridge driver does not remove the PCI IO resource
    from the host bridge resource windows if the pci_remap_iospace() call
    fails; this is an actual bug in that the PCI host bridge would consider the
    PCI IO resource valid (and possibly assign it to downstream devices) even
    if the kernel was not able to map the PCI host bridge memory address
    driving IO cycle to the CPU virtual address space (ie pci_remap_iospace()
    failures).
    
    Fix the PCI host bridge driver pci_remap_iospace() failure path, by
    destroying the PCI host bridge PCI IO resources retrieved through firmware
    when the pci_remap_iospace() function call fails, therefore preventing the
    kernel from adding the respective PCI IO resource to the list of PCI host
    bridge valid resources, fixing the issue.
    
    Fixes: b7e78170 ("PCI: versatile: Add DT-based ARM Versatile PB PCIe host driver")
    Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
    Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    CC: Rob Herring <robh@kernel.org>
    53f4f7ee
pci-versatile.c 6.37 KB