Re: [PATCH v2 13/17] PCI: dwc: Verify in/out regions against iATU constraints

[Rob Herring]

On Wed, May 04, 2022 at 12:46:34AM +0300, Serge Semin wrote:
> Since the DWC PCIe driver private data now contains the iATU inbound and
> outbound regions constraints info like alignment, minimum and maximum
> limits, we can use them to make the in- and outbound iATU regions setup
> methods more strict to the ranges a callee tries to specify.  That will
> give us the safer dw_pcie_prog_outbound_atu(),
> dw_pcie_prog_ep_outbound_atu() and dw_pcie_prog_inbound_atu() functions.
> 
> First of all let's update the outbound ATU entries setup methods to
> returning the operation status. The methods will fail either in case if
> the range is failed to be activated or the passed region doesn't fulfill
> iATU constraints. Secondly the passed to the
> dw_pcie_prog_{ep_}outbound_atu() methods region-related parameters are
> verified against the detected iATU regions constraints. In particular the
> region limit address must not overflow the lower/upper limit CSR RW-fields
> otherwise the specified range will be just silently clamped. That
> verification will also protect the code from having u64 type overflow.
> Secondly let's make sure base address (CPU-address), target address
> (PCI-address) and size are properly aligned. Unaligned ranges will be
> silently aligned down (addresses) and up (limit) on writing the values to
> the corresponding registers, which in it turn may lead to unpredictable
> results like ranges virtual overlap. Finally the CPU-address alignment
> needs to be verified in the dw_pcie_prog_inbound_atu() method too as the
> DWC PCIe RC/EP registers manual demands seeing the lower bits of the in-
> and outbound iATU base address are always zeros.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 39 +++++++++++++-------
>  drivers/pci/controller/dwc/pcie-designware.h | 10 ++---
>  2 files changed, 30 insertions(+), 19 deletions(-)

Reviewed-by: Rob Herring <robh@xxxxxxxxxx>