IB/rdmavt: rdmavt can handle non aligned page maps

commit e1fafdcb upstream.

The initial code for rdmavt carried with it a restriction that was a
vestige from the qib driver, that to dma map a page it had to be less
than a page size. This is not the case on modern hardware, both qib and
hfi1 will be just fine with unaligned map requests.

This fixes a 4.8 regression where by an IPoIB transfer of > PAGE_SIZE
will hang because the dma map page call always fails. This was
introduced after commit 5faba546 ("IB/ipoib: Report SG feature
regardless of HW UD CSUM capability") added the capability to use SG by
default. Rather than override this, the HW supports it, so allow SG.
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/infiniband/sw/rdmavt/dma.c

@@ -90,9 +90,6 @@ static u64 rvt_dma_map_page(struct ib_device *dev, struct page *page,
 	if (WARN_ON(!valid_dma_direction(direction)))
 		return BAD_DMA_ADDRESS;
 
-	if (offset + size > PAGE_SIZE)
-		return BAD_DMA_ADDRESS;
-
 	addr = (u64)page_address(page);
 	if (addr)
 		addr += offset;