Re: [PATCH v4 09/13] x86/hyperlaunch: add domain id parsing to domain config

[dmkhn@xxxxxxxxx]

On Thu, Apr 17, 2025 at 01:48:31PM +0100, Alejandro Vallejo wrote:
> From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> 
> Introduce the ability to specify the desired domain id for the domain
> definition. The domain id will be populated in the domid property of the
> domain node in the device tree configuration.
> 
> Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Alejandro Vallejo <agarciav@xxxxxxx>
> ---
> v4:
>   * Add missing newline
>   * Adjusted printks
>   * Checked domid node against list of outstanding domids.
> ---
>  xen/arch/x86/setup.c            |  5 ++--
>  xen/common/domain-builder/fdt.c | 51 ++++++++++++++++++++++++++++++++-
>  2 files changed, 53 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 76ceb5221f..04ad2d0937 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1033,8 +1033,9 @@ static struct domain *__init create_dom0(struct 
> boot_info *bi)
>      if ( iommu_enabled )
>          dom0_cfg.flags |= XEN_DOMCTL_CDF_iommu;
> 
> -    /* Create initial domain.  Not d0 for pvshim. */
> -    bd->domid = get_initial_domain_id();
> +    if ( bd->domid == DOMID_INVALID )
> +        /* Create initial domain.  Not d0 for pvshim. */
> +        bd->domid = get_initial_domain_id();
>      d = domain_create(bd->domid, &dom0_cfg, pv_shim ? 0 : CDF_privileged);
>      if ( IS_ERR(d) )
>          panic("Error creating d%u: %ld\n", bd->domid, PTR_ERR(d));
> diff --git a/xen/common/domain-builder/fdt.c b/xen/common/domain-builder/fdt.c
> index c0f526a4ce..0d3c713041 100644
> --- a/xen/common/domain-builder/fdt.c
> +++ b/xen/common/domain-builder/fdt.c
> @@ -2,6 +2,7 @@
>  /*
>   * Copyright (C) 2024, Apertus Solutions, LLC
>   */
> +#include <xen/domain.h>
>  #include <xen/err.h>
>  #include <xen/init.h>
>  #include <xen/lib.h>
> @@ -178,12 +179,54 @@ static int __init fdt_read_multiboot_module(const void 
> *fdt, int node,
>  static int __init process_domain_node(
>      struct boot_info *bi, const void *fdt, int dom_node)
>  {
> -    int node;
> +    int node, property;
>      struct boot_domain *bd = &bi->domains[bi->nr_domains];
>      const char *name = fdt_get_name(fdt, dom_node, NULL) ?: "unknown";
>      int address_cells = fdt_address_cells(fdt, dom_node);
>      int size_cells = fdt_size_cells(fdt, dom_node);
> 
> +    fdt_for_each_property_offset(property, fdt, dom_node)
> +    {
> +        const struct fdt_property *prop;
> +        const char *prop_name;
> +        int name_len, rc;
> +
> +        prop = fdt_get_property_by_offset(fdt, property, NULL);
> +        if ( !prop )
> +            continue; /* silently skip */
> +
> +        prop_name = fdt_get_string(fdt, fdt32_to_cpu(prop->nameoff), 
> &name_len);
> +
> +        if ( !strncmp(prop_name, "domid", name_len) )
> +        {
> +            uint32_t val = DOMID_INVALID;
> +
> +            if ( (rc = fdt_prop_as_u32(prop, &val)) )
> +            {
> +                printk(XENLOG_ERR
> +                       "  failed processing domain id for domain %s\n", 
> name);
> +                return rc;
> +            }
> +            if ( val >= DOMID_FIRST_RESERVED )
> +            {
> +                printk(XENLOG_ERR "  invalid domain id for domain %s\n", 
> name);
> +                return -EINVAL;
> +            }
> +
> +            for ( unsigned int i = 0; i < bi->nr_domains; i++ )
> +            {
> +                if ( bi->domains[i].domid == val )
> +                {
> +                    printk(XENLOG_ERR "  duplicate id for domain %s\n", 
> name);
> +                    return -EINVAL;
> +                }
> +            }
> +
> +            bd->domid = val;
> +            printk(XENLOG_INFO "  domid: %d\n", bd->domid);
> +        }
> +    }
> +
>      fdt_for_each_subnode(node, fdt, dom_node)
>      {
>          if ( !fdt_node_check_compatible(fdt, node, "multiboot,kernel") )
> @@ -249,6 +292,12 @@ static int __init process_domain_node(
>          return -ENODATA;
>      }
> 
> +    if ( bd->domid == DOMID_INVALID )
> +        bd->domid = get_initial_domain_id();
> +    else if ( bd->domid != get_initial_domain_id() )
> +        printk(XENLOG_WARNING
> +               "Warning: Unsuported boot with missing initial domid\n");

s/Unsuported/Unsupported/

Also, add bd->domid to the printout?

> +
>      return 0;
>  }
> 
> --
> 2.43.0
> 
>