>>> On 06.12.10 at 21:59, Olaf Hering <olaf@xxxxxxxxx> wrote:
> --- xen-unstable.hg-4.1.22459.orig/xen/arch/x86/mm/guest_walk.c
> +++ xen-unstable.hg-4.1.22459/xen/arch/x86/mm/guest_walk.c
> @@ -93,11 +93,12 @@ static inline void *map_domain_gfn(struc
> uint32_t *rc)
> {
> /* Translate the gfn, unsharing if shared */
> +retry:
> *mfn = gfn_to_mfn_unshare(p2m, gfn_x(gfn), p2mt, 0);
> if ( p2m_is_paging(*p2mt) )
> {
> - p2m_mem_paging_populate(p2m, gfn_x(gfn));
> -
> + if ( p2m_mem_paging_populate(p2m, gfn_x(gfn)) )
> + goto retry;
> *rc = _PAGE_PAGED;
> return NULL;
> }
Is this retry loop (and similar ones later in the patch) guaranteed
to be bounded in some way?
> --- xen-unstable.hg-4.1.22459.orig/xen/arch/x86/mm/p2m.c
> +++ xen-unstable.hg-4.1.22459/xen/arch/x86/mm/p2m.c
> @@ -2805,13 +2806,13 @@ void p2m_mem_paging_populate(struct p2m_
> /* Pause domain */
> if ( v->domain->domain_id == d->domain_id )
> {
> - vcpu_pause_nosync(v);
> req.flags |= MEM_EVENT_FLAG_VCPU_PAUSED;
> + ret = 1;
> }
> else if ( p2mt != p2m_ram_paging_out && p2mt != p2m_ram_paged )
> {
> /* gfn is already on its way back and vcpu is not paused */
> - return;
> + goto populate_out;
Do you really need a goto here (i.e. are you foreseeing to get stuff
added between the label and the return below)?
> }
>
> /* Send request to pager */
> @@ -2820,6 +2821,14 @@ void p2m_mem_paging_populate(struct p2m_
> req.vcpu_id = v->vcpu_id;
>
> mem_event_put_request(d, &req);
> +
> + if ( req.flags & MEM_EVENT_FLAG_VCPU_PAUSED )
> + {
> + wait_event(d->wq, mfn_valid(gfn_to_mfn(p2m, gfn, &p2mt)) &&
> !p2m_is_paging(p2mt));
> + }
> +
> +populate_out:
> + return ret;
> }
>
> int p2m_mem_paging_prep(struct p2m_domain *p2m, unsigned long gfn)
> --- xen-unstable.hg-4.1.22459.orig/xen/include/asm-x86/p2m.h
> +++ xen-unstable.hg-4.1.22459/xen/include/asm-x86/p2m.h
> @@ -474,7 +474,8 @@ int p2m_mem_paging_evict(struct p2m_doma
> /* Tell xenpaging to drop a paged out frame */
> void p2m_mem_paging_drop_page(struct p2m_domain *p2m, unsigned long gfn);
> /* Start populating a paged out frame */
> -void p2m_mem_paging_populate(struct p2m_domain *p2m, unsigned long gfn);
> +/* retval 1 means the page is present on return */
> +int p2m_mem_paging_populate(struct p2m_domain *p2m, unsigned long gfn);
Isn't this a case where you absolutely need the return value checked?
If so, you will want to add __must_check here.
Jan
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