Re: [PATCH 01/12] xen: introduce xen_dom_flags

[Jan Beulich <jbeulich@suse.com>]

On 15.04.2020 03:02, Stefano Stabellini wrote:
> We are passing an extra special boolean flag at domain creation to
> specify whether we want to the domain to be privileged (i.e. dom0) or
> not. Another flag will be introduced later in this series.
> 
> Introduce a new struct xen_dom_flags and move the privileged flag to it.
> Other flags will be added to struct xen_dom_flags.

I'm unsure whether introducing a 2nd structure is worth it here.
We could as well define some internal-use-only flags for
struct xen_domctl_createdomain's respective field.

> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -529,7 +529,8 @@ static bool emulation_flags_ok(const struct domain *d, uint32_t emflags)
>  }
>  
>  int arch_domain_create(struct domain *d,
> -                       struct xen_domctl_createdomain *config)
> +                       struct xen_domctl_createdomain *config,
> +                       struct xen_dom_flags *flags)

const (also elsewhere)?

> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -706,6 +706,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>          .max_maptrack_frames = -1,
>      };
>      const char *hypervisor_name;
> +    struct xen_dom_flags flags = { !pv_shim };

Here and elsewhere please use field designators right away, even if
there's only a single field now.

> @@ -363,7 +363,7 @@ struct domain *domain_create(domid_t domid,
>      ASSERT(is_system_domain(d) ? config == NULL : config != NULL);
>  
>      /* Sort out our idea of is_control_domain(). */
> -    d->is_privileged = is_priv;
> +    d->is_privileged =  flags ? flags->is_priv : false;

Stray double blanks.

> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -364,6 +364,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
>      bool_t copyback = 0;
>      struct xen_domctl curop, *op = &curop;
>      struct domain *d;
> +    struct xen_dom_flags flags ={ false };

Missing blank.

> --- a/xen/include/xen/domain.h
> +++ b/xen/include/xen/domain.h
> @@ -63,8 +63,13 @@ void arch_vcpu_destroy(struct vcpu *v);
>  int map_vcpu_info(struct vcpu *v, unsigned long gfn, unsigned offset);
>  void unmap_vcpu_info(struct vcpu *v);
>  
> +struct xen_dom_flags {
> +    bool is_priv;

Use a single bit bitfield instead? May even want to consider passing
this struct by value then.

Jan