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

[Sergio Lopez]

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.

Microvm only supports booting PVH-enabled Linux ELF images. Booting
other PVH-enabled kernels may be possible, but due to the lack of ACPI
and firmware, we're relying on the command line for specifying the
location of the virtio-mmio transports. If there's an interest on
using this machine type with other kernels, we'll try to find some
kind of middle ground solution.

This is the list of the exposed IO ports and MMIO regions when running
in non-legacy mode:

address-space: memory
    00000000d0000000-00000000d00001ff (prio 0, i/o): virtio-mmio
    00000000d0000200-00000000d00003ff (prio 0, i/o): virtio-mmio
    00000000d0000400-00000000d00005ff (prio 0, i/o): virtio-mmio
    00000000d0000600-00000000d00007ff (prio 0, i/o): virtio-mmio
    00000000d0000800-00000000d00009ff (prio 0, i/o): virtio-mmio
    00000000d0000a00-00000000d0000bff (prio 0, i/o): virtio-mmio
    00000000d0000c00-00000000d0000dff (prio 0, i/o): virtio-mmio
    00000000d0000e00-00000000d0000fff (prio 0, i/o): virtio-mmio
    00000000fee00000-00000000feefffff (prio 4096, i/o): kvm-apic-msi

address-space: I/O
  0000000000000000-000000000000ffff (prio 0, i/o): io
    0000000000000020-0000000000000021 (prio 0, i/o): kvm-pic
    0000000000000040-0000000000000043 (prio 0, i/o): kvm-pit
    000000000000007e-000000000000007f (prio 0, i/o): kvmvapic
    00000000000000a0-00000000000000a1 (prio 0, i/o): kvm-pic
    00000000000004d0-00000000000004d0 (prio 0, i/o): kvm-elcr
    00000000000004d1-00000000000004d1 (prio 0, i/o): kvm-elcr

A QEMU instance with the microvm machine type can be invoked this way:

 - Normal mode:

qemu-system-x86_64 -M microvm -m 512m -smp 2 \
 -kernel vmlinux -append "console=hvc0 root=/dev/vda" \
 -nodefaults -no-user-config \
 -chardev pty,id=virtiocon0,server \
 -device virtio-serial-device \
 -device virtconsole,chardev=virtiocon0 \
 -drive id=test,file=test.img,format=raw,if=none \
 -device virtio-blk-device,drive=test \
 -netdev tap,id=tap0,script=no,downscript=no \
 -device virtio-net-device,netdev=tap0

 - Legacy mode:

qemu-system-x86_64 -M microvm,legacy -m 512m -smp 2 \
 -kernel vmlinux -append "console=ttyS0 root=/dev/vda" \
 -nodefaults -no-user-config \
 -drive id=test,file=test.img,format=raw,if=none \
 -device virtio-blk-device,drive=test \
 -netdev tap,id=tap0,script=no,downscript=no \
 -device virtio-net-device,netdev=tap0 \
 -serial stdio


Changelog:
v3:
  - Add initrd support (thanks Stefano).

v2:
  - Drop "[PATCH 1/4] hw/i386: Factorize CPU routine".
  - Simplify machine definition (thanks Eduardo).
  - Remove use of unneeded NUMA-related callbacks (thanks Eduardo).
  - Add a patch to factorize PVH-related functions.
  - Replace use of Linux's Zero Page with PVH (thanks Maran and Paolo).


Sergio Lopez (4):
  hw/virtio: Factorize virtio-mmio headers
  hw/i386: Add an Intel MPTable generator
  hw/i386: Factorize PVH related functions
  hw/i386: Introduce the microvm machine type

 default-configs/i386-softmmu.mak            |   1 +
 hw/i386/Kconfig                             |   4 +
 hw/i386/Makefile.objs                       |   2 +
 hw/i386/microvm.c                           | 550 ++++++++++++++++++++
 hw/i386/mptable.c                           | 156 ++++++
 hw/i386/pc.c                                | 120 +----
 hw/i386/pvh.c                               | 113 ++++
 hw/i386/pvh.h                               |  10 +
 hw/virtio/virtio-mmio.c                     |  35 +-
 hw/virtio/virtio-mmio.h                     |  60 +++
 include/hw/i386/microvm.h                   |  82 +++
 include/hw/i386/mptable.h                   |  36 ++
 include/standard-headers/linux/mpspec_def.h | 182 +++++++
 13 files changed, 1209 insertions(+), 142 deletions(-)
 create mode 100644 hw/i386/microvm.c
 create mode 100644 hw/i386/mptable.c
 create mode 100644 hw/i386/pvh.c
 create mode 100644 hw/i386/pvh.h
 create mode 100644 hw/virtio/virtio-mmio.h
 create mode 100644 include/hw/i386/microvm.h
 create mode 100644 include/hw/i386/mptable.h
 create mode 100644 include/standard-headers/linux/mpspec_def.h

--
2.21.0