Re: [Xen-devel] [PATCH v3.1 10/15] xen/x86: split Dom0 build into PV and PVHv2

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.10.16 at 10:59, <roger.pau@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/domain_build.c
> +++ b/xen/arch/x86/domain_build.c
> @@ -191,10 +191,8 @@ struct vcpu *__init alloc_dom0_vcpu0(struct domain *dom0)
>  }
>  
>  #ifdef CONFIG_SHADOW_PAGING
> -static bool_t __initdata opt_dom0_shadow;
> +bool __initdata opt_dom0_shadow;
>  boolean_param("dom0_shadow", opt_dom0_shadow);
> -#else
> -#define opt_dom0_shadow 0
>  #endif

I think the new option parsing would better go here, avoiding the need
for this change. Making dom0_hvm visible globally is the less intrusive
variant.

> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -67,6 +67,16 @@ unsigned long __read_mostly cr4_pv32_mask;
>  static bool_t __initdata opt_dom0pvh;
>  boolean_param("dom0pvh", opt_dom0pvh);
>  
> +/*
> + * List of parameters that affect Dom0 creation:
> + *
> + *  - hvm               Create a PVHv2 Dom0.
> + *  - shadow            Use shadow paging for Dom0.
> + */
> +static void parse_dom0_param(char *s);

Please try to avoid such forward declarations.

> @@ -1543,6 +1574,14 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>      if ( opt_dom0pvh )
>          domcr_flags |= DOMCRF_pvh | DOMCRF_hap;
>  
> +    if ( dom0_hvm )
> +    {
> +        domcr_flags |= DOMCRF_hvm |
> +                       ((hvm_funcs.hap_supported && !opt_dom0_shadow) ?
> +                         DOMCRF_hap : 0);
> +        config.emulation_flags = XEN_X86_EMU_LAPIC|XEN_X86_EMU_IOAPIC;
> +    }

If you wire this up here already, instead of later in the series, what's
the effect of someone using this option? Crash?

Jan


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