On Thu, Apr 30, 2020 at 03:28:46PM +0200, Vitaly Kuznetsov wrote:
> Wanpeng Li <kernellwp@xxxxxxxxx> writes:
>
> > From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> >
> > Introduce generic fastpath handler to handle MSR fastpath, VMX-preemption
> > timer fastpath etc, move it after vmx_complete_interrupts() in order that
> > later patch can catch the case vmexit occurred while another event was
> > being delivered to guest. There is no obversed performance difference for
> > IPI fastpath testing after this move.
> >
> > Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> > Cc: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> > Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> > ---
> > arch/x86/kvm/vmx/vmx.c | 21 ++++++++++++++++-----
> > 1 file changed, 16 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index 3ab6ca6..9b5adb4 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -6583,6 +6583,20 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp)
> > }
> > }
> >
> > +static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
> > +{
> > + if (!is_guest_mode(vcpu)) {
>
> Nitpick: do we actually expect to have any fastpath handlers anytime
> soon? If not, we could've written this as
>
> if (is_guest_mode(vcpu))
> return EXIT_FASTPATH_NONE;
>
> and save on identation)
Agreed. An alternative approach would be to do the check in the caller, e.g.
if (is_guest_mode(vcpu))
return EXIT_FASTPATH_NONE;
return vmx_exit_handlers_fastpath(vcpu);
I don't have a strong preference either way.
> > + switch (to_vmx(vcpu)->exit_reason) {
> > + case EXIT_REASON_MSR_WRITE:
> > + return handle_fastpath_set_msr_irqoff(vcpu);
> > + default:
> > + return EXIT_FASTPATH_NONE;
> > + }
> > + }
> > +
> > + return EXIT_FASTPATH_NONE;
> > +}
> > +
> > bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
> >
> > static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
> > @@ -6757,17 +6771,14 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
> > if (unlikely(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
> > return EXIT_FASTPATH_NONE;
> >
> > - if (!is_guest_mode(vcpu) && vmx->exit_reason == EXIT_REASON_MSR_WRITE)
> > - exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
> > - else
> > - exit_fastpath = EXIT_FASTPATH_NONE;
> > -
> > vmx->loaded_vmcs->launched = 1;
> > vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
> >
> > vmx_recover_nmi_blocking(vmx);
> > vmx_complete_interrupts(vmx);
> >
> > + exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
No need for capturing the result in a local variable, just return the function
call.
> > +
> > return exit_fastpath;
> > }
>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>
> --
> Vitaly
>
