Re: [Xen-devel] [PATCH V6 4/4] x86/mm: Make use of the default access param from xc_altp2m_create_view

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 12/23/19 2:04 PM, Alexandru Stefan ISAILA wrote:
> At this moment the default_access param from xc_altp2m_create_view is
> not used.
> 
> This patch assigns default_access to p2m->default_access at the time of
> initializing a new altp2m view.

That's certainly not what it looks like.  It looks like you're changing
it from...

> @@ -2562,7 +2564,7 @@ static int p2m_activate_altp2m(struct domain *d,
unsigned int idx)
>          goto out;
>      }
>
> -    p2m->default_access = hostp2m->default_access;
> +    p2m->default_access = hvmmem_default_access;
>      p2m->domain = hostp2m->domain;
>      p2m->global_logdirty = hostp2m->global_logdirty;
>      p2m->min_remapped_gfn = gfn_x(INVALID_GFN);

...hostp2m->default_access to...

> @@ -340,7 +340,10 @@ static bool xenmem_access_to_p2m_access(struct
p2m_domain *p2m,
>          *paccess = memaccess[xaccess];
>          break;
>      case XENMEM_access_default:
> -        *paccess = p2m->default_access;
> +        if ( !p2m )
> +            *paccess = p2m_access_rwx;
> +        else
> +            *paccess = p2m->default_access;
>          break;
>      default:
>          return false;

...p2m_access_rwx (by passing NULL in to this function in
p2m_init_next_altp2m).

Why don't you...

> -int p2m_init_next_altp2m(struct domain *d, uint16_t *idx)
> +int p2m_init_next_altp2m(struct domain *d, uint16_t *idx,
> +                         xenmem_access_t hvmmem_default_access)
>  {
>      int rc = -EINVAL;
>      unsigned int i;
> +    p2m_access_t a;
> +    struct p2m_domain *p2m;
> +
> +    if ( hvmmem_default_access > XENMEM_access_default ||
> +         !xenmem_access_to_p2m_access(NULL, hvmmem_default_access, &a) )
> +        return rc;
>
>      altp2m_list_lock(d);
>

...pass in hostp2m here?

Also...

> @@ -2606,7 +2616,8 @@ 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);
> +        p2m = d->arch.altp2m_p2m[i];

What's this about?

 -George

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