Skip to main content

KVM Virtualization based on OpenSBI-H

RevyOS provides KVM support for TH1520 platform, based on OpenSBI-H.

Currently supported & verified boards:

  • Milk-V Meles
  • Sipeed Lichee Pi 4A
warning

OpenSBI-H support on TH1520 is experimental. Do expect issues like long KVM boot time, slow console output, or significant performance loss in specific use cases.

Install Packages​

note

Older system versions are not supported, please use the latest system image.

Before proceeding, you must do a full system upgrade, and install kernel version 6.6.77, which comes with kvm module.

Once the installation is completed, do a system reboot.

sudo apt update; sudo apt upgrade -y
sudo apt install -y th1520-mainline-opensbi-h qemu-system wget linux-image-6.6.77-th1520
# If you need to boot the VM with U-Boot:
# sudo apt install -y u-boot-qemu
sudo reboot

Verification​

If you already connected UART serial to your board, you will see the following log output during boot:

Hypervisor Extension      : Emulated
Shadow PT Space Base      : 0x3ff000000
Shadow PT Space Size      : 4096 pages

After booting into the system, you can check /proc/cpuinfo:

grep isa /proc/cpuinfo

Which should looks like this (every core's ISA part has H extension added):

processor       : 0
hart            : 0
isa             : rv64imafdch_zicntr_zicsr_zifencei_zihpm_xtheadvector
mmu             : sv39
uarch           : thead,c910
mvendorid       : 0x5b7
marchid         : 0x0
mimpid          : 0x0

processor       : 1
hart            : 1
isa             : rv64imafdch_zicntr_zicsr_zifencei_zihpm_xtheadvector
mmu             : sv39
uarch           : thead,c910
mvendorid       : 0x5b7
marchid         : 0x0
mimpid          : 0x0

processor       : 2
hart            : 2
isa             : rv64imafdch_zicntr_zicsr_zifencei_zihpm_xtheadvector
mmu             : sv39
uarch           : thead,c910
mvendorid       : 0x5b7
marchid         : 0x0
mimpid          : 0x0

processor       : 3
hart            : 3
isa             : rv64imafdch_zicntr_zicsr_zifencei_zihpm_xtheadvector
mmu             : sv39
uarch           : thead,c910
mvendorid       : 0x5b7
marchid         : 0x0
mimpid          : 0x0

Usage​

Load kvm kernel module.

sudo modprobe kvm

Check dmesg：

$ sudo dmesg | grep kvm
[ 1645.703407] kvm [762]: hypervisor extension available
[ 1645.708548] kvm [762]: using Sv39x4 G-stage page table format
[ 1645.714352] kvm [762]: VMID 0 bits available

We provide a KVM demo based on busybox, which comes with a static built coremark binary for your convenience.

warning

You might see unreasonably slow execution time for coremark. This is expected. For now, benchmark results might not reflect real VM performance.

wget https://mirror.iscas.ac.cn/revyos/extra/kvm_demo/rootfs_kvm_guest.img \
     https://mirror.iscas.ac.cn/revyos/extra/kvm_demo/start_vm.sh \
     https://mirror.iscas.ac.cn/revyos/extra/kvm_demo/Image \

Start the KVM:

chmod +x start_vm.sh; ./start_vm.sh

The following warnings by qemu-system-riscv64 are expected and can be safely ignored:

qemu-system-riscv64: warning: disabling h extension for hart 0x0 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zba extension for hart 0x0 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zbb extension for hart 0x0 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zbc extension for hart 0x0 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zbs extension for hart 0x0 because privilege spec version does not match
qemu-system-riscv64: warning: disabling sstc extension for hart 0x0 because privilege spec version does not match
qemu-system-riscv64: warning: disabling h extension for hart 0x1 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zba extension for hart 0x1 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zbb extension for hart 0x1 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zbc extension for hart 0x1 because privilege spec version does not match
qemu-system-riscv64: warning: disabling zbs extension for hart 0x1 because privilege spec version does not match
qemu-system-riscv64: warning: disabling sstc extension for hart 0x1 because privilege spec version does not match

Press Enter to active the console:

[   13.274754] Run /init as init process
           _  _
          | ||_|
          | | _ ____  _   _  _  _ 
          | || |  _ \| | | |\ \/ /
          | || | | | | |_| |/    \
          |_||_|_| |_|\____|\_/\_/

               Busybox Rootfs

Please press Enter to activate this console.
/ #

Screen record (running on a Milk-V Meles):

asciicast

CoreMark results as follows:

/ # coremark
2K performance run parameters for coremark.
CoreMark Size    : 666
Total ticks      : 19343
Total time (secs): 19.343000
Iterations/Sec   : 10339.657757
Iterations       : 200000
Compiler version : GCC13.2.0
Compiler flags   : -O2   -lrt
Memory location  : Please put data memory location here
                        (e.g. code in flash, data on heap etc)
seedcrc          : 0xe9f5
[0]crclist       : 0xe714
[0]crcmatrix     : 0x1fd7
[0]crcstate      : 0x8e3a
[0]crcfinal      : 0x4983
Correct operation validated. See README.md for run and reporting rules.
CoreMark 1.0 : 10339.657757 / GCC13.2.0 -O2   -lrt / Heap
/ #

Restore​

Revert to the original OpenSBI and then reboot.

sudo apt install th1520-mainline-opensbi -y

Credits​