Re: [Xen-devel] [PATCH 7/8] x86/hyperv: retrieve vp_index from Hyper-V

[Paul Durrant <pdurrant@xxxxxxxxx>]

On Sun, 29 Dec 2019 at 18:35, Wei Liu <wl@xxxxxxx> wrote:
>
> This will be useful when invoking hypercall that targets specific
> vcpu(s).
>
> Signed-off-by: Wei Liu <liuwe@xxxxxxxxxxxxx>
> ---
>  xen/arch/x86/guest/hyperv/hyperv.c | 12 ++++++++++++
>  xen/include/asm-x86/guest/hyperv.h |  1 +
>  2 files changed, 13 insertions(+)
>
> diff --git a/xen/arch/x86/guest/hyperv/hyperv.c 
> b/xen/arch/x86/guest/hyperv/hyperv.c
> index 67667936e9..da3a8cd85d 100644
> --- a/xen/arch/x86/guest/hyperv/hyperv.c
> +++ b/xen/arch/x86/guest/hyperv/hyperv.c
> @@ -29,6 +29,7 @@ struct ms_hyperv_info __read_mostly ms_hyperv;
>  void *hv_hypercall;
>  static struct page_info *hv_hypercall_page;
>  DEFINE_PER_CPU_READ_MOSTLY(struct hyperv_pcpu_page, hv_pcpu_input_arg);
> +DEFINE_PER_CPU_READ_MOSTLY(unsigned int, hv_vp_index);
>
>  static const struct hypervisor_ops ops;
>  const struct hypervisor_ops *__init hyperv_probe(void)
> @@ -115,15 +116,26 @@ static void setup_hypercall_pcpu_arg(void)
>      this_cpu(hv_pcpu_input_arg).mapping = mapping;
>  }
>
> +static void setup_vp_index(void)
> +{
> +    uint64_t vp_index_msr;
> +
> +    rdmsrl(HV_X64_MSR_VP_INDEX, vp_index_msr);
> +
> +    this_cpu(hv_vp_index) = vp_index_msr;
> +}

Is it worth a separate function vs. bundling this into
setup_hypercall_pcpu_arg()?

  Paul

> +
>  static void __init setup(void)
>  {
>      setup_hypercall_page();
>      setup_hypercall_pcpu_arg();
> +    setup_vp_index();
>  }
>
>  static void ap_setup(void)
>  {
>      setup_hypercall_pcpu_arg();
> +    setup_vp_index();
>  }
>
>  static const struct hypervisor_ops ops = {
> diff --git a/xen/include/asm-x86/guest/hyperv.h 
> b/xen/include/asm-x86/guest/hyperv.h
> index 83f297468f..4b635829f3 100644
> --- a/xen/include/asm-x86/guest/hyperv.h
> +++ b/xen/include/asm-x86/guest/hyperv.h
> @@ -70,6 +70,7 @@ struct hyperv_pcpu_page {
>      void *mapping;
>  };
>  DECLARE_PER_CPU(struct hyperv_pcpu_page, hv_pcpu_input_arg);
> +DECLARE_PER_CPU(unsigned int, hv_vp_index);
>
>  const struct hypervisor_ops *hyperv_probe(void);
>
> --
> 2.20.1
>

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