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? Paolo