Re: [PATCH 6/6] x86/mem-paging: consistently use gfn_t

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 16/04/2020 16:48, Jan Beulich wrote:
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -2151,16 +2151,17 @@ static int mod_l1_entry(l1_pgentry_t *pl
>                paging_mode_translate(pg_dom) )
>           {
>               p2m_type_t p2mt;
> +            unsigned long gfn = l1e_get_pfn(nl1e);
How about making gfn a gfn_t directly? This would avoid code churn when...

>               p2m_query_t q = l1e_get_flags(nl1e) & _PAGE_RW ?
>                               P2M_ALLOC | P2M_UNSHARE : P2M_ALLOC;
>   
> -            page = get_page_from_gfn(pg_dom, l1e_get_pfn(nl1e), &p2mt, q);
> +            page = get_page_from_gfn(pg_dom, gfn, &p2mt, q);
... I am going to convert get_page_from_gfn() to use typesafe gfn. See [1].

> @@ -89,16 +88,15 @@ void p2m_mem_paging_drop_page(struct dom
>    * already sent to the pager. In this case the caller has to try again until 
> the
>    * gfn is fully paged in again.
>    */
> -void p2m_mem_paging_populate(struct domain *d, unsigned long gfn_l)
> +void p2m_mem_paging_populate(struct domain *d, gfn_t gfn)
>   {
>       struct vcpu *v = current;
>       vm_event_request_t req = {
>           .reason = VM_EVENT_REASON_MEM_PAGING,
> -        .u.mem_paging.gfn = gfn_l
> +        .u.mem_paging.gfn = gfn_x(gfn)
>       };
>       p2m_type_t p2mt;
>       p2m_access_t a;
> -    gfn_t gfn = _gfn(gfn_l);
>       mfn_t mfn;
>       struct p2m_domain *p2m = p2m_get_hostp2m(d);
>       int rc = vm_event_claim_slot(d, d->vm_event_paging);
> @@ -107,7 +105,7 @@ void p2m_mem_paging_populate(struct doma
>       if ( rc == -EOPNOTSUPP )
>       {
>           gdprintk(XENLOG_ERR, "Dom%d paging gfn %lx yet no ring in place\n",
> -                 d->domain_id, gfn_l);
> +                 d->domain_id, gfn_x(gfn));
Please use PRI_gfn in the format string to match the argument change.

Cheers,

[1] 
https://lore.kernel.org/xen-devel/20200322161418.31606-18-julien@xxxxxxx/
--
Julien Grall