Hi, all, On Tue, Apr 14, 2020 at 12:45 PM Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> wrote: > > On Tue, 14 Apr 2020 09:40:26 +0800 > maobibo <maobibo@xxxxxxxxxxx> wrote: > > > On 04/13/2020 04:18 PM, Jiaxun Yang wrote: > > > On Mon, 13 Apr 2020 15:30:09 +0800 > > > Huacai Chen <chenhc@xxxxxxxxxx> wrote: > > > > > >> We are preparing to add KVM support for Loongson-3. VZ extension is > > >> fully supported in Loongson-3A R4+, and we will not care about old > > >> CPUs (at least now). We already have a full functional Linux kernel > > >> (based on Linux-5.4.x LTS) and QEMU (based on 5.0.0-rc2) and their > > >> git repositories are here: > > >> > > >> QEMU: https://github.com/chenhuacai/qemu > > >> Kernel: https://github.com/chenhuacai/linux > > >> > > >> Of course these two repositories need to be rework and not suitable > > >> for upstream (especially the commits need to be splitted). We show > > >> them here is just to tell others what we have done, and how > > >> KVM/Loongson will look like. > > >> > > >> Our plan is make the KVM host side be upstream first, and after > > >> that, we will make the KVM guest side and QEMU emulator be > > >> upstream. > > > > > > + Aleksandar as QEMU/MIPS mainatiner > > > > > > I was involved in KVM/Loongson development a bit and also intend to > > > help with mainline these works. > > > > > > After dealing with basic LS7A PCH kernel support, I'm going to > > > cooperate with Huacai and anyone who interested in to deal with > > > following stuff: > > > > > > - Basic QEMU/TCG support for Loongson64 instructions. > > > Well, it seems unrelated with KVM, but that would make > > > development easier with cross ISA emulation. I'm not going > > > to implement all the features like Loongson's page table fast walk > > > extension and binary translation extension but I'll ensure > > > any binary compiled with march=loongson3a can run flawlessly on > > > TCG. > > > > > > - Design of Loongson-VIRT QEMU machine > > > It is nearly impossible to bring a real Loongson system into > > > QEMU. Both RS780E and LS7A PCH have tons of unreasonable > > > design that would make the emulation extremely complex, Loongson > > > company's KVM implementation[1] has already proofed that, > > > thay're now in the hell. So we all agreed that we should > > > build a machine from draft. I think we should reuse existing infra > > > as far as possible to reduce our work load. I'm planing to use > > > pci-host-cam-generic together with VIRTIO PCI devices and a > > > a strip down version of loongson,liointc-1.0a to build a > > > pure PCI based system. But if any one have better idea please just > > > tell us, I'm still considering how to implement SMP-IPI and > > > ACPI stuff. > > Hi Bibo, > Thanks for your response. > > + Xing Li as I heard he is in charge of KVM from Loongson's news post. > > > It is a good job to add kvm virtualization support on loongson64 > > platform. I agree that we should define common virt machine hardware > > system, however the compiled kernel binary should be the same with > > host system, else it will bring out trouble for customers to > > differentiate them between guest system and host system. > > I'm planing to use DeviceTree to pass device information between QEMU > and guest kernel. So we can upgrade VM design at any moment without > breaking Host Guest kernel compatibility. > > > > For pci host bridge emulation, I suggest that gpex pcie host bridge > > should be used, since it supports pcie hotplug and arm/riscv uses > > this pcie host bridge. > > > gpex is basically a pci-host-cam-generic at kernel point of view. I'm > planing to reuse it too. I agree to use GPEX, and the qemu in github is updated to use GPEX. > > > > > For virtual interrupt controller, it should support MSI/MSIX > > interrupt, irqchip in kernel, IRQFD, vhost/vfio etc. I have no idea > > how to define virtual interrupt controller now. > > Yes, APIC from x86 and GIC from Arm are all bonded closely with their > architecture so we can't reuse them. Probably what we need is a > modified version of EXTIOI from Loongson-3A4000. > > Does Loongson have a plan to implement hardware virtual irqchip? If so > we must align with it's design. > > My plan is we can firstly implement a very simple IRQCHIP instead of > complex one which only handle UART and PCI INTx. That is enough to make > the system work. After that we can sit and discuss how to implement a > complicated version to archive more features. > > > > > > > regards > > bibo,mao > > > [...]
