On 04/12/19 14:33, Catherine Ho wrote: > Hi Paolo > [sorry to resend it, seems to reply it incorrectly] > > On Wed, 4 Dec 2019 at 19:23, Paolo Bonzini <pbonzini@xxxxxxxxxx > <mailto:pbonzini@xxxxxxxxxx>> wrote: > > On 04/12/19 09:50, Catherine Ho wrote: > > Commit 20a78b02d315 ("target/i386: add VMX features") unconditionally > > add vmx msr entry although older host kernels don't include them. > > > > But old host kernel + newest qemu will cause a qemu crash as follows: > > qemu-system-x86_64: error: failed to set MSR 0x480 to 0x0 > > target/i386/kvm.c:2932: kvm_put_msrs: Assertion `ret == > > cpu->kvm_msr_buf->nmsrs' failed. > > > > This fixes it by relaxing the condition. > > This is intentional. The VMX MSR entries should not have been added. > What combination of host kernel/QEMU are you using, and what QEMU > command line? > > > Host kernel: 4.15.0 (ubuntu 18.04) > Qemu: https://gitlab.com/virtio-fs/qemu/tree/virtio-fs-dev > cmdline: qemu-system-x86_64 -M pc -cpu host --enable-kvm -smp 8 \ > -m 4G,maxmem=4G > > But before 20a78b02d315, the older kernel + latest qemu can boot guest > successfully. Ok, so the problem is that some MSR didn't exist in that version. Which one it is? Can you make it conditional, similar to MSR_IA32_VMX_VMFUNC? Thanks, Paolo
