Re: [Xen-devel] [PATCH 3/6] x86/pvh: allow PVH Dom0 to use the debug IO port console

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.10.18 at 11:42, <roger.pau@xxxxxxxxxx> wrote:
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -681,6 +681,17 @@ Flag that makes a dom0 boot in PVHv2 mode.
>  Flag that makes a dom0 use shadow paging. Only works when "pvh" is
>  enabled.
>  
> +> `debug-ioport`
> +
> +> Default: `false`
> +
> +Flag that enables the HVM debug console for a PVH Dom0. Xen will trap 
> accesses
> +to IO port 0xe9 so that Dom0 kernel can print output using this IO port 
> before
> +setting up the hypercall page.
> +
> +Note this option is not enabled by default because it might clash with 
> hardware
> +on the system using IO port 0xe9 and should only be used for debug purposes.

You also want to extend the "List of" at the top of the option.

> --- a/xen/arch/x86/dom0_build.c
> +++ b/xen/arch/x86/dom0_build.c
> @@ -212,12 +212,16 @@ struct vcpu *__init alloc_dom0_vcpu0(struct domain 
> *dom0)
>  bool __initdata opt_dom0_shadow;
>  #endif
>  bool __initdata dom0_pvh;
> +#ifdef CONFIG_HVM
> +bool __initdata opt_dom0_debug_ioport;
> +#endif

And dom0_pvh does not go into this same conditional?

> @@ -236,6 +240,10 @@ static int __init parse_dom0_param(const char *s)
>  #ifdef CONFIG_SHADOW_PAGING
>          else if ( (val = parse_boolean("shadow", s, ss)) >= 0 )
>              opt_dom0_shadow = val;
> +#endif
> +#ifdef CONFIG_HVM
> +        else if ( (val = parse_boolean("debug-ioport", s, ss)) >= 0 )
> +            opt_dom0_debug_ioport = val;
>  #endif
>          else
>              rc = -EINVAL;
> @@ -433,6 +441,11 @@ int __init dom0_setup_permissions(struct domain *d)
>          rc |= ioports_deny_access(d, pmtmr_ioport, pmtmr_ioport + 3);
>      /* PCI configuration space (NB. 0xcf8 has special treatment). */
>      rc |= ioports_deny_access(d, 0xcfc, 0xcff);
> +#ifdef CONFIG_HVM
> +    if ( is_hvm_domain(d) && opt_dom0_debug_ioport )
> +        /* HVM debug console IO port. */
> +        rc |= ioports_deny_access(d, 0xe9, 0xe9);

I think we finally need a manifest constant for this port number.

Jan



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