+static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu) +{
- struct vcpu_vmx *vmx = to_vmx(vcpu);
- if (!cpu_feature_enabled(X86_FEATURE_FRED) ||
!guest_cpuid_has(vcpu, X86_FEATURE_FRED))return;- /* Enable loading guest FRED MSRs from VMCS */
- vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
- /*
* Enable saving guest FRED MSRs into VMCS and loading host FRED MSRs* from VMCS.*/- vm_exit_controls_setbit(vmx,
VM_EXIT_ACTIVATE_SECONDARY_CONTROLS);
- secondary_vm_exit_controls_setbit(vmx,
SECONDARY_VM_EXIT_SAVE_IA32_FRED|
SECONDARY_VM_EXIT_LOAD_IA32_FRED);
all above vmcs controls need to be cleared if guest doesn't enumerate FRED, see
Good point, the user space could set cpuid multiple times...
Clearing VM_EXIT_ACTIVATE_SECONDARY_CONTROLS may be problematic when new bits are added to secondary vmcs controls. Why not keep VM_EXIT_ACTIVATE_SECONDARY_CONTROLS always on if it is supported? or you see any perf impact?
I think it from the other way, why keeps hw loading it on every vmentry even if it's not used by a guest?
Different CPUs may implement it in different ways, which we can't assume.
Other features needing it should set it separately, say with a refcount.