Re: [PATCH v2 12/15] x86/hyperlaunch: specify dom0 mode with device tree

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.12.2024 17:57, Daniel P. Smith wrote:
> Enable selecting the mode in which the domain will be built and ran. This
> includes:
> 
> - whether it will be either a 32/64 bit domain

I can't spot anything like this in the code changes.

> --- a/xen/arch/x86/domain-builder/fdt.c
> +++ b/xen/arch/x86/domain-builder/fdt.c
> @@ -94,6 +94,25 @@ static int __init process_domain_node(
>              bd->domid = (domid_t)val;
>              printk("  domid: %d\n", bd->domid);
>          }
> +        else if ( strncmp(prop_name, "mode", name_len) == 0 )
> +        {
> +            if ( fdt_prop_as_u32(prop, &bd->mode) != 0 )
> +            {
> +                printk("  failed processing mode for domain %s\n", name);
> +                return -EINVAL;
> +            }
> +
> +            printk("  mode: ");
> +            if ( !(bd->mode & BUILD_MODE_PARAVIRT) )
> +            {
> +                if ( bd->mode & BUILD_MODE_ENABLE_DM )
> +                    printk("HVM\n");
> +                else
> +                    printk("PVH\n");
> +            }
> +            else
> +                printk("PV\n");

Shorter and less indentation as

            if ( bd->mode & BUILD_MODE_PARAVIRT )
                printk("PV\n");
            else if ( bd->mode & BUILD_MODE_ENABLE_DM )
                printk("HVM\n");
            else
                printk("PVH\n");

> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1016,7 +1016,8 @@ static struct domain *__init create_dom0(struct 
> boot_info *bi)
>      struct boot_domain *bd = &bi->domains[0];
>      struct domain *d;
>  
> -    if ( opt_dom0_pvh )
> +    if ( opt_dom0_pvh ||
> +         (bi->hyperlaunch_enabled && !(bd->mode & BUILD_MODE_PARAVIRT)) )

And then dropping BUILD_MODE_ENABLE_DM on the floor?

Also shouldn't this be

    if ( bi->hyperlaunch_enabled
         ? bd->mode & BUILD_MODE_PARAVIRT
         : opt_dom0_pvh )

as it can't do any good to honor a conflicting command line option.
Command line doc then will want amending to clarify that the option
will be ignored in certain cases.

Jan