On Wed, Mar 05, 2025 at 06:11:22AM +0000, Wathsala Wathawana Vithanage wrote: > By not enabling TPH in device-specific mode, hypervisors can ensure that > setting an ST in a device-specific location (like queue contexts) will have no > effect. VMs should also not be allowed to enable TPH. So many workloads run inside VMs now for security reasons that is not a reasonable approach. > I believe this could > be enforced by trapping (causing VM exits) on MSI-X/ST table writes. Yes, I think this was always part of the plan for virtualization when using a MSI-X table. > Having said that, regardless of this proposal or the availability of kernel > TPH support, a VFIO driver could enable TPH and set an arbitrary ST on the > MSI-X/ST table or a device-specific location on supported platforms. If the > driver doesn't have a list of valid STs, it can enumerate 8- or 16-bit STs and > measure access latencies to determine valid ones. And you think it is absolutely true that no TPH value can cause a platform malfunction or security failure? Jason
