Interface proposal for the split TD partitioning VMM #355
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Add design doc INTERFACES-OF-SPLIT-TDP-VMM.md and related picture resources. This design doc majorly takes about the interfaces between the user mode VMM and the kernel mode VMM, which are implemented via the file based syscall ABIs. Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
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The markdown doc is converted to a pdf file, which is now uploaded to this PR. |
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This draft PR is opened to collect review comments and discussions, but not to merge.
The TD partitioning VMM was implemented fully in the coconut-svsm kernel mode, which runs the coconut-svsm as a L1 VMM in TD and a Linux OS as a L2 guest. The code is published here.
Following the development plan, most parts of this TD partitioning VMM should be moved to the user mode for security reasons, while keeping the necessary parts (e.g., executing TDCALL instruction) left in the svsm kernel. We made a document, available for preview here, which discusses the high-level architecture of the split TD partitioning VMM and outlines the key VMM interfaces between user mode and kernel mode. In short, the proposal is to use the common file based syscalls ABI, e.g., open, ioctl, mmap as the VMM interfaces, and clone syscall to create multiple vCPU threads which shares the same user mode address space.
Before moving forward, we would like to use this PR to collect the review comments from the community about this proposal and possibility of extending it for SEV user mode VMM, as well as any alternative proposals that the community prefers. We would greatly appreciate it if you could take some time to review and share your thoughts.