Hello,
> Qcom SoCs making use of ARM SMMU require BDF to SID translation table in
> the driver to properly map the SID for the PCIe devices based on their BDF
> identifier. This is currently achieved with the help of
> qcom_pcie_config_sid_1_9_0() function for SoCs supporting the 1_9_0 config.
>
> But With newer Qcom SoCs starting from SM8450, BDF to SID translation is
> set to bypass mode by default in hardware. Due to this, the translation
> table that is set in the qcom_pcie_config_sid_1_9_0() is essentially
> unused and the default SID is used for all endpoints in SoCs starting from
> SM8450.
>
> This is a security concern and also warrants swapping the DeviceID in DT
> while using the GIC ITS to handle MSIs from endpoints. The swapping is
> currently done like below in DT when using GIC ITS:
>
> /*
> * MSIs for BDF (1:0.0) only works with Device ID 0x5980.
> * Hence, the IDs are swapped.
> */
> msi-map = <0x0 &gic_its 0x5981 0x1>,
> <0x100 &gic_its 0x5980 0x1>;
>
> Here, swapping of the DeviceIDs ensure that the endpoint with BDF (1:0.0)
> gets the DeviceID 0x5980 which is associated with the default SID as per
> the iommu mapping in DT. So MSIs were delivered with IDs swapped so far.
> But this also means the Root Port (0:0.0) won't receive any MSIs (for PME,
> AER etc...)
>
> So let's fix these issues by clearing the BDF to SID bypass mode for all
> SoCs making use of the 1_9_0 config. This allows the PCIe devices to use
> the correct SID, thus avoiding the DeviceID swapping hack in DT and also
> achieving the isolation between devices.
Applied to controller/qcom, thank you!
[1/1] PCI: qcom: Enable BDF to SID translation properly
https://git.kernel.org/pci/pci/c/b9bc750e1193
Krzysztof
