On Sun, Oct 06, 2024 at 10:34:19PM +0300, Dmitry Baryshkov wrote: > On Sat, Oct 05, 2024 at 02:53:53AM GMT, Mukesh Ojha wrote: > > Qualcomm is looking to enable remote processors on the SA8775p SoC > > running KVM Linux host and is currently trying to figure out an > > upstream-compatible solution for the IOMMU translation scheme problem it > > is facing when SoCs running with KVM. This issue arises due to > > differences in how IOMMU translation is currently handled on SoCs > > running Qualcomm EL2 hypervisor(QHEE) where IOMMU translation for any > > device is completely owned by it and the other issue is that remote > > processors firmware does not contain resource table where these IOMMU > > configuration setting will be present. > > > > Qualcomm SoCs running with the QHEE(EL2) have been utilizing the > > Peripheral Authentication Service (PAS) from its TrustZone (TZ) firmware > > to securely authenticate and reset via a single SMC call > > _auth_and_reset_. This call first gets trapped to QHEE, which then > > makes a call to TZ for authentication. Once it is done, the call returns > > to QHEE, which sets up the IOMMU translation scheme for these remote > > processors and later brings them out of reset. The design of the > > Qualcomm EL2 hypervisor dictates that the Linux host OS running at EL1 > > is not allowed to set up IOMMU translation for remote processors, > > and only a single stage is being configured for them. > > > > To make the remote processors’ bring-up (PAS) sequence > > hypervisor-independent, the auth_and_reset SMC call is now entirely > > handled by TZ. However, the problem of IOMMU handling still remains with > > the KVM host, which has no knowledge of the remote processors’ IOMMU > > configuration. > > > > We have looked up one approach where SoC remoteproc device tree could > > contain resources like iommus for remoteproc carveout and qcom,devmem > > specific binding for device memory needed for remoteproc and these > > properties are optional and will only be overlaid by the firmware if it > > is running with non-QHEE based hypervisor like KVM. > > Can you follow the approach that has been implemented for existing > systems (ChromeOS) not using QHEE? See drivers/remoteproc/qcom_q6v5_adsp.c > If this approach can not be used, please describe why. > The intent is to reuse same PAS based remoteproc implementation assisted by TZ with or without QHEE while qcom_q6v5_adsp.c caters to independent control at Linux. So it better suites to support it from qcom_q6v5_pas.c . regards Shiraz
