Re: [Qemu-devel] [PATCH v3 0/4] Introduce the microvm machine type

[Sergio Lopez <slp@redhat.com>]

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Peter Maydell <peter.maydell@linaro.org> writes:

> On Tue, 2 Jul 2019 at 13:14, Sergio Lopez <slp@redhat.com> wrote:
>>
>> Microvm is a machine type inspired by both NEMU and Firecracker, and
>> constructed after the machine model implemented by the latter.
>>
>> It's main purpose is providing users a KVM-only machine type with fast
>> boot times, minimal attack surface (measured as the number of IO ports
>> and MMIO regions exposed to the Guest) and small footprint (specially
>> when combined with the ongoing QEMU modularization effort).
>>
>> Normally, other than the device support provided by KVM itself,
>> microvm only supports virtio-mmio devices. Microvm also includes a
>> legacy mode, which adds an ISA bus with a 16550A serial port, useful
>> for being able to see the early boot kernel messages.
>
> Could we use virtio-pci instead of virtio-mmio? virtio-mmio is
> a bit deprecated and tends not to support all the features that
> virtio-pci does. It was introduced mostly as a stopgap while we
> didn't have pci support in the aarch64 virt machine, and remains
> for legacy "we don't like to break existing working setups" rather
> than as a recommended config for new systems.

Using virtio-pci implies keeping PCI and ACPI support, defeating a
significant part of microvm's purpose.

What are the issues with the current state of virtio-mmio? Is there a
way I can help to improve the situation?

Sergio.



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