Hi Julien > -----Original Message----- > From: Julien Grall <jul...@xen.org> > Sent: Thursday, May 12, 2022 6:54 PM > To: Penny Zheng <penny.zh...@arm.com>; xen-devel@lists.xenproject.org > Cc: Wei Chen <wei.c...@arm.com>; Stefano Stabellini > <sstabell...@kernel.org>; Bertrand Marquis <bertrand.marq...@arm.com>; > Volodymyr Babchuk <volodymyr_babc...@epam.com> > Subject: Re: [PATCH v3 5/8] xen/arm: Add additional reference to owner > domain when the owner is allocated > > > > On 12/05/2022 10:11, Penny Zheng wrote: > > @@ -827,6 +858,37 @@ static int __init allocate_shared_memory(struct > domain *d, > > } > > } > > > > + /* > > + * Get the right amount of references per page, which is the number of > > + * borrow domains. > > + */ > > + ret = acquire_nr_borrower_domain(d, pbase, psize, &nr_borrowers); > > + if ( ret ) > > + return ret; > > + > > + /* > > + * Instead of let borrower domain get a page ref, we add as many > > + * additional reference as the number of borrowers when the owner > > + * is allocated, since there is a chance that owner is created > > + * after borrower. > > + */ > > + page = mfn_to_page(smfn); > Where do you check that the range [smfn, smfn + nr_pages] is actual RAM? > If there are none, then you should use mfn_valid() for each mfn to ensure > there will be a struct page for it. >
Actually, before this, in acquire_shared_memory_bank, we will finally call into acquire_staticmem_pages to acquire [smfn, smfn + nr_pages], and in there, we will do the check. See xen/common/page_alloc.c:acquire_staticmem_pages:2676 > Cheers, > > -- > Julien Grall
