Re: [RFC PATCH 1/1] server extension: PCIe requirements
Josh Scheid
On Mon, Jun 14, 2021 at 4:02 PM Greg Favor <gfavor@...> wrote:
I understand that IOPMP is not an IOMMU, but to the extent that it is a general "bus master memory protection" widget, it can be used by M-mode to ensure simple things, such as that S-mode-SW-controlled PCIe initiators can not access address regions not accessible by S-mode. There's value in memory protection even without full virtualization support. I'm questioning how vague the memory protection "requirement" should be to the extent that it ends up being usable and sufficient to provide a defined level of assurance. For example, the platform spec could avoid mentioning the IOPMP proposal, but state that the platform is required to have a mechanism to allow M-mode SW to control (including prevent) PCIe initiator access to regions of system address space. While remaining open to custom implementations, it's clear on the functional intent. -Josh
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