[GH-ISSUE #7] Support PVM-based deployment #3

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opened 2026-10-29 14:18:12 +00:00 by bsakaguchi · 2 comments

bsakaguchi commented

2026-10-29 14:18:12 +00:00

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Originally created by @LSX-s-Software on GitHub (Jul 27, 2026).
Original GitHub issue: https://github.com/kvcache-ai/AgentENV/issues/7

Originally assigned to: @LSX-s-Software on GitHub.

Motivation

PVM enables users to deploy AgentENV on a cloud server with no nested virtualization support, with all sandbox instances running inside PVM-backed Micro-VMs.

Background

PVM, originally proposed in the paper PVM: Efficient Shadow Paging for Deploying Secure Containers in Cloud-native Environment, is a page-table-based nested virtualization framework built on top of KVM. Unlike conventional nested virtualization, PVM does not require the host hypervisor to expose hardware virtualization extensions (Intel VT-x / AMD-V) to the guest.

Originally created by @LSX-s-Software on GitHub (Jul 27, 2026). Original GitHub issue: https://github.com/kvcache-ai/AgentENV/issues/7 Originally assigned to: @LSX-s-Software on GitHub. ## Motivation PVM enables users to deploy AgentENV on a cloud server **with no nested virtualization support**, with all sandbox instances running inside PVM-backed Micro-VMs. ## Background PVM, originally proposed in the paper [*PVM: Efficient Shadow Paging for Deploying Secure Containers in Cloud-native Environment*](https://dl.acm.org/doi/10.1145/3600006.3613158), is a **page-table-based nested virtualization framework** built on top of KVM. Unlike conventional nested virtualization, PVM does not require the host hypervisor to expose hardware virtualization extensions (Intel VT-x / AMD-V) to the guest.

bsakaguchi

2026-10-29 14:18:12 +00:00

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bsakaguchi commented

2026-10-29 14:18:13 +00:00

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@dushulin commented on GitHub (Jul 28, 2026):

hi~Have you considered using machines that support nested virtualization? Is the PVM technology mature? It doesn't appear to have been merged into the main branch yet.

@dushulin commented on GitHub (Jul 28, 2026): hi~Have you considered using machines that support nested virtualization? Is the PVM technology mature? It doesn't appear to have been merged into the main branch yet.

bsakaguchi commented

2026-10-29 14:18:14 +00:00

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@LSX-s-Software commented on GitHub (Jul 28, 2026):

hi~Have you considered using machines that support nested virtualization? Is the PVM technology mature? It doesn't appear to have been merged into the main branch yet.

Thanks for raising this.

Yes — if the infrastructure offers nested virtualization, standard KVM remains the preferred deployment option. It uses the upstream kernel virtualization stack, requires less host customization, and will remain AgentENV's default mode.

The purpose of PVM support is to provide an additional deployment path for cloud VMs where nested virtualization is not exposed. It is not intended to replace standard KVM on hosts where KVM already works.

Regarding maturity, your concern is valid. As of July 28, 2026, the x86 PVM implementation has not been merged into the upstream Linux kernel. Deploying it therefore requires a PVM-capable host kernel and an additional host module, which introduces more operational and maintenance risk than standard KVM.

At the same time, PVM is more than an early proof of concept: it was published at SOSP 2023, and the paper reports large-scale production use. We view that as evidence that the design can be practical, but not as a substitute for upstream kernel support.

For AgentENV, we plan to treat PVM as an explicit, opt-in deployment mode:

KVM remains the default and recommended mode.
Initial PVM support is limited to x86_64.
AgentENV will not automatically install or replace the host kernel.
PVM uses separate Firecracker and guest-kernel artifacts.
KVM and PVM snapshots and paused sandboxes are not interchangeable.
The deployment documentation will clearly describe the host-kernel requirements, verification steps, operational limitations, and rollback procedure.

AgentENV's PVM integration is still being prepared and has not been merged into the main branch yet. Before considering the issue complete, we want lifecycle, pause/resume, snapshot, and deployment tests to pass on an actual PVM host.

@LSX-s-Software commented on GitHub (Jul 28, 2026): > hi~Have you considered using machines that support nested virtualization? Is the PVM technology mature? It doesn't appear to have been merged into the main branch yet. Thanks for raising this. Yes — if the infrastructure offers nested virtualization, standard KVM remains the preferred deployment option. It uses the upstream kernel virtualization stack, requires less host customization, and will remain AgentENV's default mode. The purpose of PVM support is to provide an additional deployment path for **cloud VMs where nested virtualization is not exposed**. It is not intended to replace standard KVM on hosts where KVM already works. Regarding maturity, your concern is valid. As of July 28, 2026, the x86 PVM implementation has not been merged into the upstream Linux kernel. Deploying it therefore requires a PVM-capable host kernel and an additional host module, which introduces more operational and maintenance risk than standard KVM. At the same time, PVM is more than an early proof of concept: it was published at SOSP 2023, and [the paper](https://dlnext.acm.org/doi/pdf/10.1145/3600006.3613158) reports large-scale production use. We view that as evidence that the design can be practical, but not as a substitute for upstream kernel support. For AgentENV, we plan to treat PVM as an explicit, opt-in deployment mode: - KVM remains the default and recommended mode. - Initial PVM support is limited to x86_64. - AgentENV will not automatically install or replace the host kernel. - PVM uses separate Firecracker and guest-kernel artifacts. - KVM and PVM snapshots and paused sandboxes are not interchangeable. - The deployment documentation will clearly describe the host-kernel requirements, verification steps, operational limitations, and rollback procedure. AgentENV's PVM integration is still being prepared and has not been merged into the main branch yet. Before considering the issue complete, we want lifecycle, pause/resume, snapshot, and deployment tests to pass on an actual PVM host.

bsakaguchi referenced this issue

2026-10-29 14:19:52 +00:00

[PR #3] [MERGED] Update README with citation section #115