Re: [PATCH v4 10/13] x86/hyperlaunch: specify dom0 mode with device tree

[dmkhn@xxxxxxxxx]

On Thu, Apr 17, 2025 at 01:48:32PM +0100, Alejandro Vallejo wrote:
> From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> 
> 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
>   - if it will be run as a PV or HVM domain
>   - and if it will require a device model (not applicable for dom0)
> 
> In the device tree, this will be represented as a bit map that will be carried
> through into struct boot_domain.
> 
> Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> Signed-off-by: Alejandro Vallejo <agarciav@xxxxxxx>

Reviewed-by: Denis Mukhin <dmukhin@xxxxxxxx>

> ---
> v4:
>   * printk adjustments
>   * reject nodes with conflicting mode settings
> ---
>  xen/arch/x86/include/asm/boot-domain.h |  5 +++++
>  xen/arch/x86/setup.c                   |  3 ++-
>  xen/common/domain-builder/fdt.c        | 21 +++++++++++++++++++++
>  3 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/x86/include/asm/boot-domain.h 
> b/xen/arch/x86/include/asm/boot-domain.h
> index d7c6042e25..e316d4bcde 100644
> --- a/xen/arch/x86/include/asm/boot-domain.h
> +++ b/xen/arch/x86/include/asm/boot-domain.h
> @@ -13,6 +13,11 @@
>  struct boot_domain {
>      domid_t domid;
> 
> +                                          /* On     | Off    */
> +#define BUILD_MODE_PARAVIRT      (1 << 0) /* PV     | PVH/HVM */
> +#define BUILD_MODE_ENABLE_DM     (1 << 1) /* HVM    | PVH     */
> +    uint32_t mode;
> +
>      struct boot_module *kernel;
>      struct boot_module *module;
>      const char *cmdline;
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 04ad2d0937..05e3d2cf2a 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1020,7 +1020,8 @@ 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)) )
>      {
>          dom0_cfg.flags |= (XEN_DOMCTL_CDF_hvm |
>                             ((hvm_hap_supported() && !opt_dom0_shadow) ?
> diff --git a/xen/common/domain-builder/fdt.c b/xen/common/domain-builder/fdt.c
> index 0d3c713041..6809c7f917 100644
> --- a/xen/common/domain-builder/fdt.c
> +++ b/xen/common/domain-builder/fdt.c
> @@ -225,6 +225,27 @@ static int __init process_domain_node(
>              bd->domid = val;
>              printk(XENLOG_INFO "  domid: %d\n", bd->domid);
>          }
> +        else if ( !strncmp(prop_name, "mode", name_len) )
> +        {
> +            if ( (rc = fdt_prop_as_u32(prop, &bd->mode)) )
> +            {
> +                printk(XENLOG_ERR
> +                       "  failed processing mode for domain %s\n", name);
> +                return rc;
> +            }
> +
> +            if ( (bd->mode & BUILD_MODE_PARAVIRT)  &&
> +                 (bd->mode & BUILD_MODE_ENABLE_DM) )
> +            {
> +                printk(XENLOG_ERR "  mode: invalid (pv+hvm)\n");
> +                return -EINVAL;
> +            }
> +
> +            printk(XENLOG_INFO "  mode: %s\n",
> +                   (bd->mode & BUILD_MODE_PARAVIRT)  ? "pv"  :
> +                   (bd->mode & BUILD_MODE_ENABLE_DM) ? "hvm" :
> +                                                       "pvh");
> +        }
>      }
> 
>      fdt_for_each_subnode(node, fdt, dom_node)
> --
> 2.43.0
> 
>