Re: [PATCH] PCI: mvebu: Fix endianity when accessing pci emul bridge members

From: Pali Rohár
Date: Fri Aug 12 2022 - 09:58:53 EST


On Friday 12 August 2022 11:32:59 Robin Murphy wrote:
> On 2022-08-12 10:40, Pali Rohár wrote:
> > PCI emul bridge members iolimitupper, iobaseupper, memlimit and membase are
> > of type __le16, so correctly access these members via le16_to_cpu() macros.
> >
> > Fixes: 4ded69473adb ("PCI: mvebu: Propagate errors when updating PCI_IO_BASE and PCI_MEM_BASE registers")
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
> > ---
> > drivers/pci/controller/pci-mvebu.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
> > index c1ffdb06c971..00ea0836b81a 100644
> > --- a/drivers/pci/controller/pci-mvebu.c
> > +++ b/drivers/pci/controller/pci-mvebu.c
> > @@ -523,7 +523,7 @@ static int mvebu_pcie_handle_iobase_change(struct mvebu_pcie_port *port)
> > /* Are the new iobase/iolimit values invalid? */
> > if (conf->iolimit < conf->iobase ||
> > - conf->iolimitupper < conf->iobaseupper)
> > + le16_to_cpu(conf->iolimitupper) < le16_to_cpu(conf->iobaseupper))
> > return mvebu_pcie_set_window(port, port->io_target, port->io_attr,
> > &desired, &port->iowin);
> > @@ -535,10 +535,10 @@ static int mvebu_pcie_handle_iobase_change(struct mvebu_pcie_port *port)
> > * is the CPU address.
> > */
> > desired.remap = ((conf->iobase & 0xF0) << 8) |
> > - (conf->iobaseupper << 16);
> > + le16_to_cpu(conf->iobaseupper << 16);
>
> This will always give 0, even when natively LE.

You are right, I overlooked it and I put closing parenthesis at wrong
place. Bit shifting should be applied after le to cpu conversion. I will
fix it in V2.

> > desired.base = port->pcie->io.start + desired.remap;
> > desired.size = ((0xFFF | ((conf->iolimit & 0xF0) << 8) |
> > - (conf->iolimitupper << 16)) -
> > + le16_to_cpu(conf->iolimitupper << 16)) -
>
> Similarly here.
>
> Robin.
>
> > desired.remap) +
> > 1;
> > @@ -552,7 +552,7 @@ static int mvebu_pcie_handle_membase_change(struct mvebu_pcie_port *port)
> > struct pci_bridge_emul_conf *conf = &port->bridge.conf;
> > /* Are the new membase/memlimit values invalid? */
> > - if (conf->memlimit < conf->membase)
> > + if (le16_to_cpu(conf->memlimit) < le16_to_cpu(conf->membase))
> > return mvebu_pcie_set_window(port, port->mem_target, port->mem_attr,
> > &desired, &port->memwin);
> > @@ -562,8 +562,8 @@ static int mvebu_pcie_handle_membase_change(struct mvebu_pcie_port *port)
> > * window to setup, according to the PCI-to-PCI bridge
> > * specifications.
> > */
> > - desired.base = ((conf->membase & 0xFFF0) << 16);
> > - desired.size = (((conf->memlimit & 0xFFF0) << 16) | 0xFFFFF) -
> > + desired.base = ((le16_to_cpu(conf->membase) & 0xFFF0) << 16);
> > + desired.size = (((le16_to_cpu(conf->memlimit) & 0xFFF0) << 16) | 0xFFFFF) -
> > desired.base + 1;
> > return mvebu_pcie_set_window(port, port->mem_target, port->mem_attr, &desired,