On Sun, Mar 13, 2022 at 12:12 PM Ralf Ramsauer <ralf.ramsa...@oth-regensburg.de> wrote: > > Hi, > > I'm trying to run Linux/QEMU+KVM inside an emulated > qemu-system-riscv64 VM (x86 host). On latest&greatest QEMU (1416688c53), > I run Linux inside QEMU. On host side: > > qemu-system-riscv64 -nographic \ > -machine virt \ > -cpu 'rv64,h=true' \ > -smp 8 -m 8G \ > -bios $latest_opensbi \ > -kernel $latest_upstream_linux \ > […snip…] > > Inside that machine, I boot Linux with KVM enabled: > > […] > [ 0.228939] kvm [1]: hypervisor extension available > [ 0.229000] kvm [1]: using Sv48x4 G-stage page table format > [ 0.229033] kvm [1]: VMID 14 bits available > […] > > KVM seems to load correctly. Inside that machine, I compiled QEMU from > the same sources with the KVM accelerator enabled. When I try to start > QEMU with KVM enabled, I get > > ./qemu-system-riscv64 -nographic \ > -monitor none \ > -machine virt \ > -smp 1 -m 1G \ > -bios ./pc-bios/opensbi-riscv64-generic-fw_dynamic.bin \ > -serial stdio \ > -enable-kvm > > [ 4860.559194] kvm [9942]: VCPU exit error -95 > [ 4860.584262] kvm [9942]: SEPC=0x0 SSTATUS=0x200004120 HSTATUS=0x2002001c0 > [ 4860.586839] kvm [9942]: SCAUSE=0x14 STVAL=0x0 HTVAL=0x0 HTINST=0x0 > > on the ringbuffer, together with a register dump of qemu [1] on the > console. Needless to say, but without -enable-kvm, it works fine. > > As far as I see that, SCAUSE=0x14 reports a 'Instruction Guest PF', > which would be kind of correct, if the guest's PC really tries to > execute at phys 0x0. DRAM of the 'virt' machine definition should start > at 0x80000000, where OpenSBI resides. So I wonder if an erroneous reset > PC might be the culprit… > > Before digging deeper into that issue, I wanted to ask if Qemu/KVM > inside an emulated riscv64+H-extension is actually supported, or if this > is a known bug and has some ongoing work.
RISC-V KVM should work. I haven't had a chance to try it myself though. I have CCed two people who hopefully can help. Alistair > > Thanks > Ralf > > [1] > > pc 0000000000000000 > mhartid 0000000000000000 > mstatus 0000000200000000 > mip 0000000000000000 > mie 0000000000000000 > mideleg 0000000000000000 > medeleg 0000000000000000 > mtvec 0000000000000000 > stvec 0000000000000000 > mepc 0000000000000000 > sepc 0000000000000000 > mcause 0000000000000000 > scause 0000000000000000 > mtval 0000000000000000 > stval 0000000000000000 > mscratch 0000000000000000 > sscratch 0000000000000000 > satp 0000000000000000 > x0/zero 0000000000000000 x1/ra 0000000000000000 x2/sp > 0000000000000000 x3/gp 0000000000000000 > x4/tp 0000000000000000 x5/t0 0000000000000000 x6/t1 > 0000000000000000 x7/t2 0000000000000000 > x8/s0 0000000000000000 x9/s1 0000000000000000 x10/a0 > 0000000000000000 x11/a1 00000000bf000000 > x12/a2 0000000000000000 x13/a3 0000000000000000 x14/a4 > 0000000000000000 x15/a5 0000000000000000 > x16/a6 0000000000000000 x17/a7 0000000000000000 x18/s2 > 0000000000000000 x19/s3 0000000000000000 > x20/s4 0000000000000000 x21/s5 0000000000000000 x22/s6 > 0000000000000000 x23/s7 0000000000000000 > x24/s8 0000000000000000 x25/s9 0000000000000000 x26/s10 > 0000000000000000 x27/s11 0000000000000000 > x28/t3 0000000000000000 x29/t4 0000000000000000 x30/t5 > 0000000000000000 x31/t6 0000000000000000 >
