xen/grant-table: xen_shim_domain() support

With xen-shim, allocate_xenballooned_pages() only allocates a
place-holder page (pfn 0) expecting a subsequent map_grant_ref to fix
it up.

However, this means that, until the grant operation
(GNTTABOP_map_grant_ref) provides a valid page, we cannot set
PagePrivate or save any state.

This patch elides the setting of that state if xen_shim_domain(). In
addition, gnttab_map_refs() now fills in the appropriate page returned
from the grant operation.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 7ea6fb6a2e5dd78c53a79bfea140e2e297858f7d..ab05b70d98bb0e9bb464a8a3ad0d1788a3474fd4 100644 (file)
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -804,7 +804,7 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
        int ret;
 
        ret = alloc_xenballooned_pages(nr_pages, pages);
-       if (ret < 0)
+       if (ret < 0 || xen_shim_domain())
                return ret;
 
        ret = gnttab_pages_set_private(nr_pages, pages);
@@ -1045,6 +1045,11 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                {
                        struct xen_page_foreign *foreign;
 
+                       if (xen_shim_domain()) {
+                               pages[i] = virt_to_page(map_ops[i].host_addr);
+                               continue;
+                       }
+
                        SetPageForeign(pages[i]);
                        foreign = xen_page_foreign(pages[i]);
                        foreign->domid = map_ops[i].dom;
@@ -1085,8 +1090,10 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
        if (ret)
                return ret;
 
-       for (i = 0; i < count; i++)
-               ClearPageForeign(pages[i]);
+       for (i = 0; i < count; i++) {
+               if (!xen_shim_domain())
+                       ClearPageForeign(pages[i]);
+       }
 
        return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 }
@@ -1113,7 +1120,7 @@ static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
        int pc;
 
        for (pc = 0; pc < item->count; pc++) {
-               if (page_count(item->pages[pc]) > 1) {
+               if (page_count(item->pages[pc]) > 1 && !xen_shim_domain()) {
                        unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
                        schedule_delayed_work(&item->gnttab_work,
                                              msecs_to_jiffies(delay));