Re: [PATCH v5 10/10] Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs

Nuno Das Neves
2025-03-01T01:38:04Z

On 2/27/2025 10:50 AM, Roman Kisel wrote:
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>
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> On 2/26/2025 3:08 PM, Nuno Das Neves wrote:
>> Provide a set of IOCTLs for creating and managing child partitions when
>> running as root partition on Hyper-V. The new driver is enabled via
>> CONFIG_MSHV_ROOT.
>>
>
> [...]
>
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> As I understood, the changes fall into these buckets:
>
> 1. Partition management (VPs and memory). Built of the top of fd's which
>    looks as the right approach. There is ref counting etc.
> 2. Scheduling. Here, there is the mature KVM and Xen code dto find
>    inspiration in. Xen being the Type 1 hypervisor should likely be
>    closer to MSHV in my understanding.
> 3. IOCTL code allocation. Not sure how this is allocated yet given that
>    the patch series has been through a multi-year review, that must be
>    settled by now.
> 4. IOCTLs themselves. The majority just marshals data to the
>    hypervisor.
>
This is a good summary, thanks.

> Despite the rather large size of the patch, I spot-checked the places
> where I have the chance to make an informed decision, and could not find
> anything that'd stand out as suspicious to me. Going to extrapolate that
> the patch itself should be good enough. Given that this code has been in
> development and validation for a few years, I'd vote to merge it. That
> will also enable upstreaming the rest of the VTL mode code that powers
> Azure Boost (https://github.com/microsoft/OHCL-Linux-Kernel)
>
> Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
>