On 20/06/19 10:27, Wanpeng Li wrote: > Agreed, in addition, guest can enable/disable cpuid bits by grub > parameter Through what path? Guest can disable X86_FEATURE_* but that's purely a Linux feature, the few CPUID bits that can change at runtime already call kvm_x86_ops->cpuid_update(). Paolo > , should we call kvm_x86_ops->cpuid_update() in > kvm_vcpu_reset() path to reflect the new guest cpuid influence to > exec_control? e.g. the first boot guest disable xsaves in grub, kvm > disables xsaves in exec_control; then guest reboot w/ xsaves enabled, > it still get an #UD when executing.
