Hi Gavin, Sorry for the late reply. I had to travel outside the UK urgently because of some personal challenging situation. I'm still on the transit back to the UK hence replying from my other email ID..
On Thu, Oct 17, 2024 at 8:07 AM Gavin Shan <gs...@redhat.com> wrote: > Hi Salil, > > The issues reported against on RFCv3 are still existing. I'm listing them > as below two. > Yes, the one existing I had mentioned as part of the TODO list at the end of the RFC V5. Including below two mentioned. > (1) Guest fails to start due to SVE initialization > I do not have the hardware to test this. I will not mind if you can share a patch and also test this part. > > /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \ > -accel kvm -machine virt,gic-version=host,nvdimm=on \ > -cpu host -smp maxcpus=4,cpus=1,sockets=2,clusters=2,cores=1,threads=1 \ > -m 4096M,slots=16,maxmem=128G \ > -object memory-backend-ram,id=mem0,size=2048M \ > -object memory-backend-ram,id=mem1,size=2048M \ > : > kvm_arch_init_vcpu: Error -22 from kvm_arm_sve_set_vls() > qemu-system-aarch64: Failed to initialize host vcpu 1 > > Workaround: The SVE feature bits in ID_AA64PFR0 need to be masked off in > kvm_arm_get_host_cpu_features() after the feature register's value is read > from the host. > This would happen if the kvm_arch_init_vcpu will be called again during hotplug and its SVE related config is different from the one initially configured at the KVM init time. I had included a patch to check such configuration but did not test it for any of the ARm extensions i.e. SVE, SME etc. https://lore.kernel.org/qemu-devel/20241015100012.254223-23-salil.me...@huawei.com/ > > (2) Fail to hot add vCPU whose PMU is turned off > > /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \ > -accel kvm -machine virt,gic-version=host,nvdimm=on \ > -cpu host -smp maxcpus=4,cpus=1,sockets=2,clusters=2,cores=1,threads=1 \ > -m 4096M,slots=16,maxmem=128G \ > -object memory-backend-ram,id=mem0,size=2048M \ > -object memory-backend-ram,id=mem1,size=2048M \ > : > (qemu) device_add > host-arm-cpu,id=cpu1,socket-id=0,cluster-id=1,core-id=0,thread-id=0,pmu=off > kvm_arch_init_vcpu: Error -22 from kvm_arm_vcpu_init() > qemu-system-aarch64: kvm_init_vcpu: kvm_arch_init_vcpu failed (1): Invalid > argument > > Workaround: Keep PMU on while the vCPU is hot added. > we should disallow any vCPU configuration different than already configured at the KVM during VM initialization time. Thanks > > > Thanks, > Gavin > > >
