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Commit 1affa98d authored by Daniel De Graaf's avatar Daniel De Graaf Committed by Konrad Rzeszutek Wilk
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xen/gntdev: remove erronous use of copy_to_user 



Since there is now a mapping of granted pages in kernel address space in
both PV and HVM, use it for UNMAP_NOTIFY_CLEAR_BYTE instead of accessing
memory via copy_to_user and triggering sleep-in-atomic warnings.

Signed-off-by: default avatarDaniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 16a1d022

drivers/xen/gntdev.c

+3 −10
Original line number Diff line number Diff line
@@ -312,17 +312,10 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages) 


	if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {

		int pgno = (map->notify.addr >> PAGE_SHIFT);

		if (pgno >= offset && pgno < offset + pages && use_ptemod) {

			void __user *tmp = (void __user *)

				map->vma->vm_start + map->notify.addr;

			err = copy_to_user(tmp, &err, 1);

			if (err)

				return -EFAULT;

			map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;

		} else if (pgno >= offset && pgno < offset + pages) {

			uint8_t *tmp = kmap(map->pages[pgno]);

		if (pgno >= offset && pgno < offset + pages) {

			/* No need for kmap, pages are in lowmem */

			uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));

			tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;

			kunmap(map->pages[pgno]);

			map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;

		}

	}