Re: [PATCH v4 00/20] KVM RISC-V Support

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/08/19 14:27, Anup Patel wrote:
> This series adds initial KVM RISC-V support. Currently, we are able to boot
> RISC-V 64bit Linux Guests with multiple VCPUs.

Looks good to me!  Still need an Acked-by from arch/riscv folks if I
have to merge it, otherwise they can take care of the initial merge.

Paolo

> Few key aspects of KVM RISC-V added by this series are:
> 1. Minimal possible KVM world-switch which touches only GPRs and few CSRs.
> 2. Full Guest/VM switch is done via vcpu_get/vcpu_put infrastructure.
> 3. KVM ONE_REG interface for VCPU register access from user-space.
> 4. PLIC emulation is done in user-space. In-kernel PLIC emulation, will
>    be added in future.
> 5. Timer and IPI emuation is done in-kernel.
> 6. MMU notifiers supported.
> 7. FP lazy save/restore supported.
> 8. SBI v0.1 emulation for KVM Guest available.
> 
> Here's a brief TODO list which we will work upon after this series:
> 1. Handle trap from unpriv access in reading Guest instruction
> 2. Handle trap from unpriv access in SBI v0.1 emulation
> 3. Implement recursive stage2 page table programing
> 4. SBI v0.2 emulation in-kernel
> 5. SBI v0.2 hart hotplug emulation in-kernel
> 6. In-kernel PLIC emulation
> 7. ..... and more .....
> 
> This series can be found in riscv_kvm_v4 branch at:
> https//github.com/avpatel/linux.git
> 
> Our work-in-progress KVMTOOL RISC-V port can be found in riscv_v1 branch at:
> https//github.com/avpatel/kvmtool.git
> 
> We need OpenSBI with RISC-V hypervisor extension support which can be
> found in hyp_ext_changes_v1 branch at:
> https://github.com/riscv/opensbi.git
> 
> The QEMU RISC-V hypervisor emulation is done by Alistair and is available
> in riscv-hyp-work.next branch at:
> https://github.com/alistair23/qemu.git
> 
> To play around with KVM RISC-V, here are few reference commands:
> 1) To cross-compile KVMTOOL:
>    $ make lkvm-static
> 2) To launch RISC-V Host Linux:
>    $ qemu-system-riscv64 -monitor null -cpu rv64,h=true -M virt \
>    -m 512M -display none -serial mon:stdio \
>    -kernel opensbi/build/platform/qemu/virt/firmware/fw_jump.elf \
>    -device loader,file=build-riscv64/arch/riscv/boot/Image,addr=0x80200000 \
>    -initrd ./rootfs_kvm_riscv64.img \
>    -append "root=/dev/ram rw console=ttyS0 earlycon=sbi"
> 3) To launch RISC-V Guest Linux with 9P rootfs:
>    $ ./apps/lkvm-static run -m 128 -c2 --console serial \
>    -p "console=ttyS0 earlycon=uart8250,mmio,0x3f8" -k ./apps/Image --debug
> 4) To launch RISC-V Guest Linux with initrd:
>    $ ./apps/lkvm-static run -m 128 -c2 --console serial \
>    -p "console=ttyS0 earlycon=uart8250,mmio,0x3f8" -k ./apps/Image \
>    -i ./apps/rootfs.img --debug
> 
> Changes since v3:
> - Moved patch for ISA bitmap from KVM prep series to this series
> - Make vsip_shadow as run-time percpu variable instead of compile-time
> - Flush Guest TLBs on all Host CPUs whenever we run-out of VMIDs