qemu-system-riscv64 is not found in package qemu-system-misc

I'm trying to set up xv6 on Ubuntu 18.04.5 but there is an error during make qemu:

# outputs...
qemu-system-riscv64 -machine virt -bios none -kernel kernel/kernel -m 128M -smp 3 -nographic -drive file=fs.img,if=none,format=raw,id=x0 -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
make: qemu-system-riscv64: Command not found

I found that there is no qemu-system-riscv64 under /usr/bin after installing qemu-system-misc(version 1:2.11+dfsg-1ubuntu7.36):

$ ls /usr/bin | grep qemu
qemu-img
qemu-io
qemu-nbd
qemu-system-alpha
qemu-system-cris
qemu-system-lm32
qemu-system-m68k
qemu-system-microblaze
qemu-system-microblazeel
qemu-system-moxie
qemu-system-nios2
qemu-system-or1k
qemu-system-sh4
qemu-system-sh4eb
qemu-system-tricore
qemu-system-unicore32
qemu-system-xtensa
qemu-system-xtensaeb

I've tried to install an older version of qemu-system-misc which is mentioned in Tools Used in 6.S081

At this moment in time, it seems that the package qemu-system-misc has received an update that breaks its compatibility with our kernel. If you run make qemu and the script appears to hang after

qemu-system-riscv64 -machine virt -bios none -kernel kernel/kernel -m 128M -smp 3 nographic -drive file=fs.img,if=none,format=raw,id=x0 -device virtio-blk device,drive=x0,bus=virtio-mmio-bus.0

you'll need to uninstall that package and install an older version:

$ sudo apt-get remove qemu-system-misc
$ sudo apt-get install qemu-system-misc=1:4.2-3ubuntu6

yet this version was not found.

Any solution for installing either qemu-system-riscv64 or an older version of qemu-system-misc?

Everything went right after I upgraded Ubuntu to version 20.04.2 :)