On Tue, Aug 24, 2021, Xiaoyao Li wrote: > A minor optimation to WRMSR MSR_IA32_RTIT_CTL when necessary. > > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> > --- > arch/x86/kvm/vmx/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index fada1055f325..e0a9460e4dab 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -1075,7 +1075,8 @@ static void pt_guest_exit(struct vcpu_vmx *vmx) > } > > /* Reload host state (IA32_RTIT_CTL will be cleared on VM exit). */ Could you opportunistically update the comment to call out that KVM requires VM_EXIT_CLEAR_IA32_RTIT_CTL to expose PT to the guest? E.g. something like /* * KVM's requires VM_EXIT_CLEAR_IA32_RTIT_CTL to expose PT to the guest, * i.e. RTIT_CTL is always cleared on VM-Exit. Restore it if necessary. */ With that, Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx> > - wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); > + if (vmx->pt_desc.host.ctl) > + wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); > } > > void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel, > -- > 2.27.0 >
