Re: [Xen-devel] [PATCH V2 2/2] x86/mm: Make use of the default access param from xc_altp2m_create_view

[Jan Beulich <jbeulich@suse.com>]

On 06.11.2019 16:35, Alexandru Stefan ISAILA wrote:
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -1345,13 +1345,14 @@ void setup_ept_dump(void)
>      register_keyhandler('D', ept_dump_p2m_table, "dump VT-x EPT tables", 0);
>  }
>  
> -void p2m_init_altp2m_ept(struct domain *d, unsigned int i)
> +void p2m_init_altp2m_ept(struct domain *d, unsigned int i,
> +                         p2m_access_t default_access)
>  {
>      struct p2m_domain *p2m = d->arch.altp2m_p2m[i];
>      struct p2m_domain *hostp2m = p2m_get_hostp2m(d);
>      struct ept_data *ept;
>  
> -    p2m->default_access = hostp2m->default_access;
> +    p2m->default_access = default_access;
>      p2m->domain = hostp2m->domain;
>  
>      p2m->global_logdirty = hostp2m->global_logdirty;

All of this is not EPT-specific. Before adding more infrastructure to
cover for this (here: another function parameter), how about moving
these parts into vendor-independent code?

> @@ -2572,17 +2574,36 @@ int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx)
>      altp2m_list_lock(d);
>  
>      if ( d->arch.altp2m_eptp[idx] == mfn_x(INVALID_MFN) )
> -        rc = p2m_activate_altp2m(d, idx);
> +        rc = p2m_activate_altp2m(d, idx, hostp2m->default_access);
>  
>      altp2m_list_unlock(d);
>      return rc;
>  }
>  
> -int p2m_init_next_altp2m(struct domain *d, uint16_t *idx)
> +int p2m_init_next_altp2m(struct domain *d, uint16_t *idx,
> +                         uint16_t hvmmem_default_access)
>  {
>      int rc = -EINVAL;
>      unsigned int i;
>  
> +    static const p2m_access_t memaccess[] = {
> +#define ACCESS(ac) [XENMEM_access_##ac] = p2m_access_##ac
> +        ACCESS(n),
> +        ACCESS(r),
> +        ACCESS(w),
> +        ACCESS(rw),
> +        ACCESS(x),
> +        ACCESS(rx),
> +        ACCESS(wx),
> +        ACCESS(rwx),
> +        ACCESS(rx2rw),
> +        ACCESS(n2rwx),
> +#undef ACCESS
> +    };
> +
> +    if ( hvmmem_default_access > XENMEM_access_default )
> +        return rc;
> +
>      altp2m_list_lock(d);
>  
>      for ( i = 0; i < MAX_ALTP2M; i++ )
> @@ -2590,7 +2611,7 @@ int p2m_init_next_altp2m(struct domain *d, uint16_t *idx)
>          if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
>              continue;
>  
> -        rc = p2m_activate_altp2m(d, i);
> +        rc = p2m_activate_altp2m(d, i, memaccess[hvmmem_default_access]);

Aren't you open-coding xenmem_access_to_p2m_access() here? In
no event should there be two instances of the same static array.

Jan

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