Hi Julien
> -----Original Message-----
> From: Julien Grall <jul...@xen.org>
> Sent: Tuesday, May 18, 2021 7:02 PM
> To: Penny Zheng <penny.zh...@arm.com>; xen-devel@lists.xenproject.org;
> sstabell...@kernel.org
> Cc: Bertrand Marquis <bertrand.marq...@arm.com>; Wei Chen
> <wei.c...@arm.com>; nd <n...@arm.com>
> Subject: Re: [PATCH 08/10] xen/arm: introduce reserved_page_list
>
> Hi Penny,
>
> On 18/05/2021 06:21, Penny Zheng wrote:
> > Since page_list under struct domain refers to linked pages as gueast
> > RAM
>
> s/gueast/guest/
>
Thx~
> > allocated from heap, it should not include reserved pages of static memory.
>
> You already have PGC_reserved to indicate they are "static memory". So why
> do you need yet another list?
>
> >
> > The number of PGC_reserved pages assigned to a domain is tracked in a
> > new 'reserved_pages' counter. Also introduce a new reserved_page_list
> > to link pages of static memory. Let page_to_list return
> > reserved_page_list, when flag is PGC_reserved.
> >
> > Later, when domain get destroyed or restarted, those new values will
> > help relinquish memory to proper place, not been given back to heap.
> >
> > Signed-off-by: Penny Zheng <penny.zh...@arm.com>
> > ---
> > xen/common/domain.c | 1 +
> > xen/common/page_alloc.c | 7 +++++--
> > xen/include/xen/sched.h | 5 +++++
> > 3 files changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/xen/common/domain.c b/xen/common/domain.c index
> > 6b71c6d6a9..c38afd2969 100644
> > --- a/xen/common/domain.c
> > +++ b/xen/common/domain.c
> > @@ -578,6 +578,7 @@ struct domain *domain_create(domid_t domid,
> > INIT_PAGE_LIST_HEAD(&d->page_list);
> > INIT_PAGE_LIST_HEAD(&d->extra_page_list);
> > INIT_PAGE_LIST_HEAD(&d->xenpage_list);
> > + INIT_PAGE_LIST_HEAD(&d->reserved_page_list);
> >
> > spin_lock_init(&d->node_affinity_lock);
> > d->node_affinity = NODE_MASK_ALL; diff --git
> > a/xen/common/page_alloc.c b/xen/common/page_alloc.c index
> > f1f1296a61..e3f07ec6c5 100644
> > --- a/xen/common/page_alloc.c
> > +++ b/xen/common/page_alloc.c
> > @@ -2410,7 +2410,7 @@ int assign_pages(
> >
> > for ( i = 0; i < nr_pfns; i++ )
> > {
> > - ASSERT(!(pg[i].count_info & ~PGC_extra));
> > + ASSERT(!(pg[i].count_info & ~(PGC_extra |
> > + PGC_reserved)));
> I think this change belongs to the previous patch.
>
Ok. It will be re-organized into previous commit of
"xen/arm: intruduce alloc_domstatic_pages"
> > if ( pg[i].count_info & PGC_extra )
> > extra_pages++;
> > }
> > @@ -2439,6 +2439,9 @@ int assign_pages(
> > }
> > }
> >
> > + if ( pg[0].count_info & PGC_reserved )
> > + d->reserved_pages += nr_pfns;
>
> reserved_pages doesn't seem to be ever read or decremented. So why do
> you need it?
>
Yeah, I may delete it from this Patch Serie.
Like I addressed in before commits:
"when implementing rebooting domain on static allocation, memory will be
relinquished
and right now, all shall be freed back to heap, which is not suitable for
static memory here.
` relinquish_memory(d, &d->page_list) --> put_page --> free_domheap_page`
For pages in PGC_reserved, now, I am considering that, other than giving it
back to heap,
maybe creating a new global `struct page_info*[DOMID]` value to hold.
So it is better to have a new field in struct page_info, as follows, to hold
such info.
/* Page is reserved. */
struct {
/*
* Reserved Owner of this page,
* if this page is reserved to a specific domain.
*/
domid_t reserved_owner;
} reserved;
"
So I will delete here, and re-import when implementing rebooting domain on
static allocation.
> > +
> > if ( !(memflags & MEMF_no_refcount) &&
> > unlikely(domain_adjust_tot_pages(d, nr_pfns) == nr_pfns) )
> > get_knownalive_domain(d);
> > @@ -2452,7 +2455,7 @@ int assign_pages(
> > page_set_reserved_owner(&pg[i], d);
> > smp_wmb(); /* Domain pointer must be visible before updating
> refcnt. */
> > pg[i].count_info =
> > - (pg[i].count_info & PGC_extra) | PGC_allocated | 1;
> > + (pg[i].count_info & (PGC_extra | PGC_reserved)) |
> > + PGC_allocated | 1;
>
> Same here.
I'll re-organize it to the previous commit.
>
> > page_list_add_tail(&pg[i], page_to_list(d, &pg[i]));
> > }
> >
> > diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h index
> > 3982167144..b6333ed8bb 100644
> > --- a/xen/include/xen/sched.h
> > +++ b/xen/include/xen/sched.h
> > @@ -368,6 +368,7 @@ struct domain
> > struct page_list_head page_list; /* linked list */
> > struct page_list_head extra_page_list; /* linked list (size
> > extra_pages) */
> > struct page_list_head xenpage_list; /* linked list (size
> > xenheap_pages) */
> > + struct page_list_head reserved_page_list; /* linked list (size
> > + reserved pages) */
> >
> > /*
> > * This field should only be directly accessed by
> > domain_adjust_tot_pages() @@ -379,6 +380,7 @@ struct domain
> > unsigned int outstanding_pages; /* pages claimed but not possessed
> */
> > unsigned int max_pages; /* maximum value for
> domain_tot_pages() */
> > unsigned int extra_pages; /* pages not included in
> domain_tot_pages() */
> > + unsigned int reserved_pages; /* pages of static memory */
> > atomic_t shr_pages; /* shared pages */
> > atomic_t paged_pages; /* paged-out pages */
> >
> > @@ -588,6 +590,9 @@ static inline struct page_list_head *page_to_list(
> > if ( pg->count_info & PGC_extra )
> > return &d->extra_page_list;
> >
> > + if ( pg->count_info & PGC_reserved )
> > + return &d->reserved_page_list;
> > +
> > return &d->page_list;
> > }
> >
> >
>
> Cheers,
>
> --
> Julien Grall
Cheers
Penny Zheng
