On Tue, Sep 16, 2025 at 12:34:42PM -0500, Bjorn Helgaas wrote: > I know I've asked this before, but I'm still confused about how this > is related to PCIe r7.0, sec 7.7.12, which says that if an SR-IOV > device implements internal peer-to-peer transactions, ACS is required, > and ACS P2P Egress Control must be supported.
Right, certainly for SRIOV Linux has always taken the view that VFs and PFs have NO internal loopback if there are no ACS caps. The entire industry has aligned to this because having an hidden uncontrolled internal loopback where the VF can reach the PF's BAR would be catastrophically security broken for virtualization. Virtualization is the main use case for having SRIOV in the first place, so nobody would build an insecure internal loopback.. Jason
