> From: Sean Christopherson <seanjc@xxxxxxxxxx> > Sent: Wednesday, December 29, 2021 8:10 AM > > But why even bother with an extra flag? Can't > vmx_update_exception_bitmap() get > the guest's MSR_IA32_XFD value and intercept #NM accordingly? Then you > could > even handle this fully in kvm_set_msr_common(), e.g. > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 2c9606380bca..c6c936d2b298 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3704,6 +3704,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, > struct msr_data *msr_info) > return 1; > > fpu_update_guest_xfd(&vcpu->arch.guest_fpu, data); > + /* Blah blah blah blah */ > + static_call(kvm_x86_update_exception_bitmap)(vcpu); > break; btw follow Paolo's suggestion here: https://lore.kernel.org/all/6e95b6f7-44dc-7e48-4e6e-81cf85fc11c6@xxxxxxxxxx/ He prefers to disabling xfd interception in vmx specific code instead of introducing a new callback to be called in common code. Since we want to always trap #NM after xfd interception is disabled (which is done after calling the msr common code), it also reads cleaner to call update_exception_bitmap() from vmx.c instead of here. Thanks Kevin
