Hyper-V's Virtual Secure Mode (VSM) is a virtualisation security feature that leverages the hypervisor to create secure execution environments within a guest. VSM is documented as part of Microsoft's Hypervisor Top Level Functional Specification [1]. Security features that build upon VSM, like Windows Credential Guard, are enabled by default on Windows 11, and are becoming a prerequisite in some industries. This RFC series introduces the necessary infrastructure to emulate VSM enabled guests. It is a snapshot of the progress we made so far, and its main goal is to gather design feedback. Specifically on the KVM APIs we introduce. For a high level design overview, see the documentation in patch 33. Additionally, this topic will be discussed as part of the KVM Micro-conference, in this year's Linux Plumbers Conference [2]. The series is accompanied by two repositories: - A PoC QEMU implementation of VSM [3]. - VSM kvm-unit-tests [4]. Note that this isn't a full VSM implementation. For now it only supports 2 VTLs, and only runs on uniprocessor guests. It is capable of booting Windows Sever 2016/2019, but is unstable during runtime. The series is based on the v6.6 kernel release, and depends on the introduction of KVM memory attributes, which is being worked on independently in "KVM: guest_memfd() and per-page attributes" [5]. A full Linux tree is also made available [6]. Series rundown: - Patch 2 introduces the concept of APIC ID groups. - Patches 3-12 introduce the VSM capability and basic VTL awareness into Hyper-V emulation. - Patch 13 introduces vCPU polling support. - Patches 14-31 use KVM's memory attributes to implement VTL memory protections. Introduces the VTL KMV device and secure memory intercepts. - Patch 32 is a temporary implementation of HVCALL_TRANSLATE_VIRTUAL_ADDRESS necessary to boot Windows 2019. - Patch 33 introduces documentation. Our intention is to integrate feedback gathered in the RFC and LPC while we finish the VSM implementation. In the future, we will split the series into distinct feature patch sets and upstream these independently. Thanks, Nicolas [1] https://raw.githubusercontent.com/Microsoft/Virtualization-Documentation/master/tlfs/Hypervisor%20Top%20Level%20Functional%20Specification%20v6.0b.pdf [2] https://lpc.events/event/17/sessions/166/#20231114 [3] https://github.com/vianpl/qemu/tree/vsm-rfc-v1 [4] https://github.com/vianpl/kvm-unit-tests/tree/vsm-rfc-v1 [5] https://lore.kernel.org/lkml/20231105163040.14904-1-pbonzini@xxxxxxxxxx/. [6] Full tree: https://github.com/vianpl/linux/tree/vsm-rfc-v1. There are also two small dependencies with https://marc.info/?l=kvm&m=167887543028109&w=2 and https://lkml.org/lkml/2023/10/17/972
