vfio/type1: fix vaddr_get_pfns() return in vfio_pin_page_external()

stable inclusion
from stable-v5.10.146
commit 8c6fd05cf8874e683dfb2749926363faeb3324e0
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0VX

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c6fd05cf8874e683dfb2749926363faeb3324e0



--------------------------------

commit 4ab4fcfc upstream.

vaddr_get_pfns() now returns the positive number of pfns successfully
gotten instead of zero.  vfio_pin_page_external() might return 1 to
vfio_iommu_type1_pin_pages(), which will treat it as an error, if
vaddr_get_pfns() is successful but vfio_pin_page_external() doesn't
reach vfio_lock_acct().

Fix it up in vfio_pin_page_external().  Found by inspection.

Fixes: be16c1fd ("vfio/type1: Change success value of vaddr_get_pfn()")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Message-Id: <20210308172452.38864-1-daniel.m.jordan@oracle.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com>