vdpa_sim: Use iova_shift() for the size passed to alloc_iova()

The size passed to alloc_iova() should be the size of page frames.
Now we use byte granularity for the iova domain, so it's safe to
pass the size in bytes to alloc_iova(). But it would be better to use
iova_shift() for the size to avoid future bugs if we change granularity.
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210809100923.38-1-xieyongji@bytedance.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -137,7 +137,8 @@ static dma_addr_t vdpasim_map_range(struct vdpasim *vdpasim, phys_addr_t paddr,
 	int ret;
 
 	/* We set the limit_pfn to the maximum (ULONG_MAX - 1) */
-	iova = alloc_iova(&vdpasim->iova, size, ULONG_MAX - 1, true);
+	iova = alloc_iova(&vdpasim->iova, size >> iova_shift(&vdpasim->iova),
+			  ULONG_MAX - 1, true);
 	if (!iova)
 		return DMA_MAPPING_ERROR;