2016-09-21 10:14+0800, Wanpeng Li:
> From: Wanpeng Li <wanpeng...@hotmail.com>
> 
> I observed that kvmvapic(to optimize flexpriority=N or AMD) is used 
> to boost TPR access when testing kvm-unit-test/eventinj.flat tpr case
> on my haswell desktop (w/ flexpriority, w/o APICv). Commit (8d14695f9542 
> x86, apicv: add virtual x2apic support) disable virtual x2apic mode 
> completely if w/o APICv, and the author also told me that windows guest
> can't enter into x2apic mode when he developed the APICv feature several 
> years ago. However, it is not truth currently, Interrupt Remapping and 
> vIOMMU is added to qemu and the developers from Intel test windows 8 can 
> work in x2apic mode w/ Interrupt Remapping enabled recently. 
> 
> This patch enables TPR shadow for virtual x2apic mode to boost 
> windows guest in x2apic mode even if w/o APICv.
> 
> Can pass the kvm-unit-test.
> 
> Suggested-by: Radim Krčmář <rkrc...@redhat.com>
> Suggested-by: Wincy Van <fanwenyi0...@gmail.com>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Cc: Radim Krčmář <rkrc...@redhat.com>
> Cc: Wincy Van <fanwenyi0...@gmail.com>
> Cc: Yang Zhang <yang.zhang...@gmail.com>
> Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
> ---
> v2 -> v3:
>  * introduce a new set of bitmaps and assign them in vmx_set_msr_bitmap()
> v1 -> v2: 
>  * leverage the cached msr bitmap
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> @@ -2518,10 +2520,18 @@ static void vmx_set_msr_bitmap(struct kvm_vcpu *vcpu)
>       else if (cpu_has_secondary_exec_ctrls() &&
>                (vmcs_read32(SECONDARY_VM_EXEC_CONTROL) &
>                 SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE)) {
> -             if (is_long_mode(vcpu))
> -                     msr_bitmap = vmx_msr_bitmap_longmode_x2apic;
> -             else
> -                     msr_bitmap = vmx_msr_bitmap_legacy_x2apic;
> +             if (enable_apicv && kvm_vcpu_apicv_active(vcpu)) {
> +                     if (is_long_mode(vcpu))
> +                             msr_bitmap = vmx_msr_bitmap_longmode_x2apic;
> +                     else
> +                             msr_bitmap = vmx_msr_bitmap_legacy_x2apic;
> +             } else if ((enable_apicv && !kvm_vcpu_apicv_active(vcpu)) ||
> +                             !enable_apicv) {

Could only be "else" without if here.  I'll change that when refactoring
of vmx bitmap handling, posting soon (hopefully).

> +                     if (is_long_mode(vcpu))
> +                             msr_bitmap = 
> vmx_msr_bitmap_longmode_x2apic_apicv_inactive;
> +                     else
> +                             msr_bitmap = 
> vmx_msr_bitmap_legacy_x2apic_apicv_inactive;
> +             }
>       } else {
>               if (is_long_mode(vcpu))
>                       msr_bitmap = vmx_msr_bitmap_longmode;
> @@ -4678,28 +4688,49 @@ static void vmx_disable_intercept_for_msr(u32 msr, 
> bool longmode_only)
> -static void vmx_enable_intercept_msr_read_x2apic(u32 msr)
> +static void vmx_enable_intercept_msr_read_x2apic(u32 msr, bool apicv_active)
>  {
> -     __vmx_enable_intercept_for_msr(vmx_msr_bitmap_legacy_x2apic,
> -                     msr, MSR_TYPE_R);
> -     __vmx_enable_intercept_for_msr(vmx_msr_bitmap_longmode_x2apic,
> -                     msr, MSR_TYPE_R);
> +     if (apicv_active) {
> +             __vmx_enable_intercept_for_msr(vmx_msr_bitmap_legacy_x2apic,
> +                             msr, MSR_TYPE_R);
> +             __vmx_enable_intercept_for_msr(vmx_msr_bitmap_longmode_x2apic,
> +                             msr, MSR_TYPE_R);
> +     } else {
> +             
> __vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy_x2apic_apicv_inactive,
> +                             msr, MSR_TYPE_R);
> +             
> __vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode_x2apic_apicv_inactive,
> +                             msr, MSR_TYPE_R);

Pasto here (disable vs. enable).  It's not called with !apicv_active and
the refactoring will delete the whole function, so

Reviwed-by: Radim Krčmář <rkrc...@redhat.com>

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