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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Mar 07, 2024 at 12:19:56PM +0100, Konrad Dybcio wrote: > > > On 3/7/24 12:05, Manivannan Sadhasivam wrote: > > 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. > > > > Cc: # 5.11 > > Fixes: 4c9398822106 ("PCI: qcom: Add support for configuring BDF to SID mapping for SM8250") > > Signed-off-by: Manivannan Sadhasivam > > --- > > Looks sensible.. > > Does switching away from bypass show any performance degradation? > Not at all with my throughput test on SM8450 dev board. But there shouldn't be any performance related issue since we are just forcing the hw to use a different SID (correct one) than the default one. - Mani -- மணிவண்ணன் சதாசிவம்