/*
* Keep track of foreign pages marked as PageForeign so that we don't
* return them to the remote domain prematurely.
*
* PageForeign pages are pinned down by increasing their mapcount.
*
* All other pages are simply returned as is.
*/
void __gnttab_dma_map_page(struct page *page)
{
unsigned int seq;
if (!is_running_on_xen() || !PageForeign(page))
return;
do {
seq = read_seqbegin(&gnttab_dma_lock);
if (gnttab_dma_local_pfn(page))
break;
atomic_set(&page->_mapcount, 0);
/* Make _mapcount visible before read_seqretry. */
smp_mb();
} while (unlikely(read_seqretry(&gnttab_dma_lock, seq)));
}
/* Set up the grant operations for this fragment. If it's a flipping
interface, we also set up the unmap request from here. */
static u16 netbk_gop_frag(netif_t *netif, struct netbk_rx_meta *meta,
int i, struct netrx_pending_operations *npo,
struct page *page, unsigned long size,
unsigned long offset)
{
mmu_update_t *mmu;
gnttab_transfer_t *gop;
gnttab_copy_t *copy_gop;
multicall_entry_t *mcl;
netif_rx_request_t *req;
unsigned long old_mfn, new_mfn;
old_mfn = virt_to_mfn(page_address(page));
req = RING_GET_REQUEST(&netif->rx, netif->rx.req_cons + i);
if (netif->copying_receiver) {
/* The fragment needs to be copied rather than
flipped. */
meta->copy = 1;
copy_gop = npo->copy + npo->copy_prod++;
copy_gop->flags = GNTCOPY_dest_gref;
if (PageForeign(page)) {
struct pending_tx_info *src_pend =
&pending_tx_info[page->index];
copy_gop->source.domid = src_pend->netif->domid;
copy_gop->source.u.ref = src_pend->req.gref;
copy_gop->flags |= GNTCOPY_source_gref;
} else {
copy_gop->source.domid = DOMID_SELF;
copy_gop->source.u.gmfn = old_mfn;
}
copy_gop->source.offset = offset;
copy_gop->dest.domid = netif->domid;
copy_gop->dest.offset = 0;
copy_gop->dest.u.ref = req->gref;
copy_gop->len = size;
} else {
meta->copy = 0;
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
new_mfn = alloc_mfn();
/*
* Set the new P2M table entry before
* reassigning the old data page. Heed the
* comment in pgtable-2level.h:pte_page(). :-)
*/
set_phys_to_machine(page_to_pfn(page), new_mfn);
mcl = npo->mcl + npo->mcl_prod++;
MULTI_update_va_mapping(mcl,
(unsigned long)page_address(page),
pfn_pte_ma(new_mfn, PAGE_KERNEL),
0);
mmu = npo->mmu + npo->mmu_prod++;
mmu->ptr = ((maddr_t)new_mfn << PAGE_SHIFT) |
MMU_MACHPHYS_UPDATE;
mmu->val = page_to_pfn(page);
}
gop = npo->trans + npo->trans_prod++;
gop->mfn = old_mfn;
gop->domid = netif->domid;
gop->ref = req->gref;
}
return req->id;
}
