Re: [Xen-devel] [PATCH v5 02/12] x86/hypervisor: make hypervisor_ap_setup return an error code

["Roger Pau Monné" <roger.pau@citrix.com>]

On Wed, Jan 29, 2020 at 08:20:24PM +0000, Wei Liu wrote:
> We want to be able to handle AP setup error in the upper layer.

Thanks, some comments below.

> 
> Signed-off-by: Wei Liu <liuwe@microsoft.com>
> ---
>  xen/arch/x86/guest/hypervisor.c        |  6 ++++--
>  xen/arch/x86/guest/xen/xen.c           | 11 +++++++++--
>  xen/include/asm-x86/guest/hypervisor.h |  6 +++---
>  3 files changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/x86/guest/hypervisor.c b/xen/arch/x86/guest/hypervisor.c
> index 4f27b98740..e72c92ffdf 100644
> --- a/xen/arch/x86/guest/hypervisor.c
> +++ b/xen/arch/x86/guest/hypervisor.c
> @@ -52,10 +52,12 @@ void __init hypervisor_setup(void)
>          ops->setup();
>  }
>  
> -void hypervisor_ap_setup(void)
> +int hypervisor_ap_setup(void)
>  {
>      if ( ops && ops->ap_setup )
> -        ops->ap_setup();
> +        return ops->ap_setup();
> +
> +    return 0;
>  }
>  
>  void hypervisor_resume(void)
> diff --git a/xen/arch/x86/guest/xen/xen.c b/xen/arch/x86/guest/xen/xen.c
> index 6dbc5f953f..eed8a6edae 100644
> --- a/xen/arch/x86/guest/xen/xen.c
> +++ b/xen/arch/x86/guest/xen/xen.c
> @@ -257,11 +257,18 @@ static void __init setup(void)
>      init_evtchn();
>  }
>  
> -static void ap_setup(void)
> +static int ap_setup(void)
>  {
> +    int rc;
> +
>      set_vcpu_id();
> -    map_vcpuinfo();
> +    rc = map_vcpuinfo();

map_vcpuinfo should be changed so that the BUG_ON is removed, and an
error is only returned if VCPUOP_register_vcpu_info fails and vcpu >=
XEN_LEGACY_MAX_VCPUS, else no error should be returned.

> +    if ( rc )
> +        return rc;
> +
>      init_evtchn();
> +
> +    return 0;

In order to keep this shorter, you could do:

if ( !rc )
    init_evtchn();

return rc;

Thanks, Roger.

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