Re: [PATCH v6] x86/altp2m: Aggregate get entry and populate into common funcs

["Jan Beulich" <JBeulich@suse.com>]

>>> On 23.04.19 at 16:30, <aisaila@bitdefender.com> wrote:
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -478,6 +478,43 @@ void p2m_unlock_and_tlb_flush(struct p2m_domain *p2m)
>          mm_write_unlock(&p2m->lock);
>  }
>  
> +int altp2m_get_effective_entry(struct p2m_domain *ap2m, gfn_t gfn, mfn_t *mfn,
> +                               p2m_type_t *t, p2m_access_t *a,
> +                               bool prepopulate)
> +{
> +    *mfn = ap2m->get_entry(ap2m, gfn, t, a, 0, NULL, NULL);
> +
> +    /* Check host p2m if no valid entry in alternate */
> +    if ( !mfn_valid(*mfn) && !p2m_is_hostp2m(ap2m) )
> +    {
> +        struct p2m_domain *hp2m = p2m_get_hostp2m(ap2m->domain);
> +        unsigned int page_order;
> +        int rc;
> +
> +        *mfn = __get_gfn_type_access(hp2m, gfn_x(gfn), t, a,
> +                                     P2M_ALLOC | P2M_UNSHARE, &page_order, 0);
> +
> +        rc = -ESRCH;
> +        if ( !mfn_valid(*mfn) || *t != p2m_ram_rw )
> +            return rc;
> +
> +        /* If this is a superpage, copy that first */
> +        if ( prepopulate && page_order != PAGE_ORDER_4K )
> +        {
> +            unsigned long mask = ~((1UL << page_order) - 1);
> +            gfn_t gfn_aligned = _gfn(gfn_x(gfn) & mask);
> +            mfn_t mfn_aligned = _mfn(mfn_x(*mfn) & mask);
> +
> +            rc = ap2m->set_entry(ap2m, gfn_aligned, mfn_aligned, page_order, *t, *a, 1);
> +            if ( rc )
> +                return rc;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +
>  mfn_t __get_gfn_type_access(struct p2m_domain *p2m, unsigned long gfn_l,
>                      p2m_type_t *t, p2m_access_t *a, p2m_query_t q,
>                      unsigned int *page_order, bool_t locked)

May I ask how the placement of this function was chosen? It looks
as if all its callers live inside #ifdef CONFIG_HVM sections, just this
function doesn't (reportedly causing build issues together with
later changes).

Jan



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