Move and rename some Vm traits #1105

ludfjig · 2025-12-10T21:41:12Z

Some follow up items from #924. Please review commit by commit

Moves kvm.rs/hyperv_linux.rs/hyperv_windows.rs into new vm module.
Renames Hyperv_linux.rs to mshv.rs. Renames hyperv_windows.rs to whp.rs
Renames Hypervisor trait to Vm trait
Renames HyperlightExit to VmExit
Moves some hypervisor specific code out from sandbox module, to hypervisor/vm module

Note that this PR does not modify any code (with exception of renames and moves)

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com> Clean up import paths after file move Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com> Rename hyperv_linux to mshv, hyperv_windows to whp Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Copilot

Pull request overview

This PR performs a significant refactoring of VM-related code to improve organization and naming consistency. It moves hypervisor-specific implementation files from the root hypervisor module and the sandbox module into a new hypervisor/vm submodule, renames files to use shorter and more descriptive names (mshv, whp), and renames core abstractions (Hypervisor trait → Vm trait, HyperlightExit → VmExit) to better reflect their purpose.

Key Changes:

Created new hypervisor/vm module to consolidate VM implementations (KVM, MSHV, WHP)
Renamed Hypervisor trait to Vm and HyperlightExit enum to VmExit for clearer semantics
Moved hypervisor detection logic from sandbox::hypervisor to hypervisor::vm

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/hyperlight_host/src/sandbox/mod.rs	Removed hypervisor submodule and moved `is_hypervisor_present()` to hypervisor/vm module
src/hyperlight_host/src/sandbox/hypervisor.rs	Deleted - functionality moved to hypervisor/vm/mod.rs
src/hyperlight_host/src/lib.rs	Updated public export to reference `hypervisor::vm::is_hypervisor_present`
src/hyperlight_host/src/hypervisor/vm/mod.rs	New module containing VM trait, VmExit enum, hypervisor detection, and test moved from sandbox
src/hyperlight_host/src/hypervisor/vm/whp.rs	Renamed from hyperv_windows.rs; updated trait implementation and imports
src/hyperlight_host/src/hypervisor/vm/mshv.rs	Renamed from hyperv_linux.rs; updated trait implementation and imports
src/hyperlight_host/src/hypervisor/vm/kvm.rs	Moved to vm submodule; updated trait implementation and imports
src/hyperlight_host/src/hypervisor/mod.rs	Removed Hypervisor trait, HyperlightExit enum, and old module declarations
src/hyperlight_host/src/hypervisor/hyperlight_vm.rs	Updated imports to reference vm module and new Vm/VmExit names; updated comments
src/hyperlight_host/src/hypervisor/gdb/mod.rs	Updated DebuggableVm trait to extend Vm instead of Hypervisor

src/hyperlight_host/src/hypervisor/gdb/mod.rs

src/hyperlight_host/src/hypervisor/vm/mod.rs

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

danbugs

I like the change from Hypervisor → Vm. I agree that it is more accurate. Same for VmExit over HyperlightExit.

Though, iirc, in the past, when we considered changing from hyperv_* to mshv/whp, we opted to keep the previous names.

ludfjig · 2025-12-11T18:28:28Z

I like the change from Hypervisor → Vm. I agree that it is more accurate. Same for VmExit over HyperlightExit.

Though, iirc, in the past, when we considered changing from hyperv_* to mshv/whp, we opted to keep the previous names.

THanks. I think the renaming was discarded in the past due to making a PR too hard to review

danbugs · 2025-12-11T18:54:51Z

I like the change from Hypervisor → Vm. I agree that it is more accurate. Same for VmExit over HyperlightExit.
Though, iirc, in the past, when we considered changing from hyperv_* to mshv/whp, we opted to keep the previous names.

THanks. I think the renaming was discarded in the past due to making a PR too hard to review

I think Simon also mentioned the hyperv_* names are more descriptive: #517 (comment)

jsturtevant · 2025-12-11T20:48:18Z

LGTM, I tend to agree that I perfer hyperv_linux and hyperv_windows over mshv and whp.

ludfjig · 2025-12-11T21:13:55Z

I like whp (windows hypervisor platform) because it's the name of the API we use https://learn.microsoft.com/en-us/virtualization/api/hypervisor-platform/hypervisor-platform

simongdavies

Just al little concerned about VM name since we also will have VM as an abbreviation for Virtual Memory

simongdavies · 2025-12-16T20:39:02Z

src/hyperlight_host/src/hypervisor/mod.rs

-#[cfg(kvm)]
-/// Functionality to manipulate KVM-based virtual machines
-pub(crate) mod kvm;
+pub(crate) mod vm;


Can we call this virtual_machine, #1093 introduces a vm module too (we should probably rename that to virtual_memory a well

gosh I just reviewed that and didn't notice that was vm as in virtual_memory. Should #1093 also rename vm->virtual_memory?

simongdavies · 2025-12-16T20:42:05Z

src/hyperlight_host/src/hypervisor/gdb/mod.rs

 /// Trait for VMs that support debugging capabilities.
 /// This extends the base Hypervisor trait with GDB-specific functionality.
-pub(crate) trait DebuggableVm: Hypervisor {
+pub(crate) trait DebuggableVm: Vm {


Again can we consider calling this VirtualMachine and DebuggableVirtualMachine? I agree with the rename its just the ambiguity with vm as an abbreviation for VirtualMemory

simongdavies · 2025-12-16T20:55:19Z

src/hyperlight_host/src/hypervisor/vm/mod.rs

+                }
+            } else if #[cfg(target_os = "windows")] {
+                if whp::is_hypervisor_present() {
+                    Some(HypervisorType::Whp)


I just realised that we have code in unitializedsandbox::new that checks for supported versions of windows , I don't know why that code is there and not wrapped up in the check for whp presence here , IIRC that code is to check that we are running on Windows 11 or Windows 2022 or later because we need an API that is only available on those Os versions

simongdavies · 2025-12-16T21:01:09Z

I like the change from Hypervisor → Vm. I agree that it is more accurate. Same for VmExit over HyperlightExit.
Though, iirc, in the past, when we considered changing from hyperv_* to mshv/whp, we opted to keep the previous names.

THanks. I think the renaming was discarded in the past due to making a PR too hard to review

I think Simon also mentioned the hyperv_* names are more descriptive: #517 (comment)

Well I must be mellowing rapidly since I don't really mind that renaming, I'm easy either way (although being totally contradictory to my previous comments the new names do have a certain amount of symmetry to them). Not sure about VM abbreviation though and don't like ::vm::vm much either

ludfjig added 4 commits December 10, 2025 12:39

Rename Hypervisor trait to Vm trait. Rename HyperlightExit to VmExit

9cf7847

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Move hypervisor-related functions out of sandbox module

1146fb7

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

License header + cargo fmt

bd7b26d

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

ludfjig added the kind/refactor For PRs that restructure or remove code without adding new functionality. label Dec 10, 2025

ludfjig marked this pull request as ready for review December 11, 2025 00:05

ludfjig requested review from danbugs, dblnz, devigned, jprendes, marosset, simongdavies and syntactically as code owners December 11, 2025 00:05

ludfjig requested a review from Copilot December 11, 2025 00:05

Copilot started reviewing on behalf of ludfjig December 11, 2025 00:06 View session

Copilot AI reviewed Dec 11, 2025

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Update comments based on PR feedback

6d2f287

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

ludfjig force-pushed the vm-unit-test branch from 99037b1 to 6d2f287 Compare December 11, 2025 00:18

ludfjig mentioned this pull request Dec 11, 2025

Add unit test for kvm/mshv/whp #1106

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danbugs reviewed Dec 11, 2025

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simongdavies reviewed Dec 16, 2025

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Move and rename some Vm traits #1105

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ludfjig commented Dec 10, 2025 •

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